You will find below the publication list of our pole.
For the publication list of each pole member, please see his/her personal webpage.
2008 |
Electrochemical monitoring of single cell secretion: Vesicular exocytosis and oxidative stress Article de journal C Amatore; S Arbault; M Guille; F Lemaître Chemical Reviews, 108 (7), p. 2585–2621, 2008. @article{Amatore:2008a, title = {Electrochemical monitoring of single cell secretion: Vesicular exocytosis and oxidative stress}, author = {C Amatore and S Arbault and M Guille and F Lema\^{i}tre}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49049112285&doi=10.1021%2fcr068062g&partnerID=40&md5=ae6a20b01b9ae57f75d37389b0ebe3ec}, doi = {10.1021/cr068062g}, year = {2008}, date = {2008-01-01}, journal = {Chemical Reviews}, volume = {108}, number = {7}, pages = {2585--2621}, abstract = {Several important contributions of electroanalytical techniques over the past 20 years for investigating three major biological processes at the single cell level: vesicular exocytosis, oxidative stress, and nitric oxide metabolism in brain have been reported. It is evident that molecular electrochemistry at microelectrodes enhances the understanding of central processes of cellular biology including cellular metabolism either at a single cell stage or in living tissues. Since cells have highly variable metabolism even among single genetic lines, studies performed at the single cell level allow delineating precisely the extent and limits of these variabilities.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Several important contributions of electroanalytical techniques over the past 20 years for investigating three major biological processes at the single cell level: vesicular exocytosis, oxidative stress, and nitric oxide metabolism in brain have been reported. It is evident that molecular electrochemistry at microelectrodes enhances the understanding of central processes of cellular biology including cellular metabolism either at a single cell stage or in living tissues. Since cells have highly variable metabolism even among single genetic lines, studies performed at the single cell level allow delineating precisely the extent and limits of these variabilities. |
Fourier transform to analyse reaction-diffusion dynamics in a microsystem Article de journal A Estévez-Torres; T Le Saux; C Gosse; A Lemarchand; A Bourdoncle; L Jullien Lab on a Chip, 8 (7), p. 1205–1209, 2008. @article{Estevez-Torres:2008, title = {Fourier transform to analyse reaction-diffusion dynamics in a microsystem}, author = {A Est\'{e}vez-Torres and T Le Saux and C Gosse and A Lemarchand and A Bourdoncle and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-46149125030&doi=10.1039%2fb805412f&partnerID=40&md5=61edf13ed55e8879919bd89b45ba779a}, doi = {10.1039/b805412f}, year = {2008}, date = {2008-01-01}, journal = {Lab on a Chip}, volume = {8}, number = {7}, pages = {1205--1209}, abstract = {An integrated approach relying on a microsystem is introduced to easily extract, from a single experiment and with a global robust bi-exponential fit, an extensive set of thermodynamic, kinetic, and diffusion parameters governing associations in solution. © The Royal Society of Chemistry.}, keywords = {}, pubstate = {published}, tppubtype = {article} } An integrated approach relying on a microsystem is introduced to easily extract, from a single experiment and with a global robust bi-exponential fit, an extensive set of thermodynamic, kinetic, and diffusion parameters governing associations in solution. © The Royal Society of Chemistry. |
Integration of various stacking processes in carrier ampholyte-based capillary electrophoresis Article de journal J -M Busnel; T Le Saux; S Descroix; H H Girault; M -C Hennion; S Terabe; G Peltre Journal of Chromatography A, 1182 (2), p. 226–232, 2008. @article{Busnel:2008, title = {Integration of various stacking processes in carrier ampholyte-based capillary electrophoresis}, author = {J -M Busnel and T Le Saux and S Descroix and H H Girault and M -C Hennion and S Terabe and G Peltre}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38849137225&doi=10.1016%2fj.chroma.2007.12.079&partnerID=40&md5=4caf52eac131ffda6bd95a11a598c783}, doi = {10.1016/j.chroma.2007.12.079}, year = {2008}, date = {2008-01-01}, journal = {Journal of Chromatography A}, volume = {1182}, number = {2}, pages = {226--232}, abstract = {Field-enhanced sample stacking, field-enhanced sample injection as well as electrokinetic supercharging have been successfully integrated in carrier ampholyte-based capillary electrophoresis. Through the analysis of different test sample mixtures, it has been shown that the carrier ampholyte-based background electrolytes, in spite of their very low conductivity, allow efficient online preconcentration of analytes by field-amplified techniques. Sensitivity enhancement factors of the same magnitude as those usually encountered with classical conductive background electrolytes have been obtained in such carrier ampholyte-based buffers. Depending on the online preconcentration method that has been integrated, sensitivity enhancement factors between 50 and several thousands have been reached. © 2008 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Field-enhanced sample stacking, field-enhanced sample injection as well as electrokinetic supercharging have been successfully integrated in carrier ampholyte-based capillary electrophoresis. Through the analysis of different test sample mixtures, it has been shown that the carrier ampholyte-based background electrolytes, in spite of their very low conductivity, allow efficient online preconcentration of analytes by field-amplified techniques. Sensitivity enhancement factors of the same magnitude as those usually encountered with classical conductive background electrolytes have been obtained in such carrier ampholyte-based buffers. Depending on the online preconcentration method that has been integrated, sensitivity enhancement factors between 50 and several thousands have been reached. © 2008 Elsevier B.V. All rights reserved. |
Multiphotonic excitation and solvation dynamics effects on the femtosecond transient absorption of O-hexamethoxyhypericin Article de journal C Ley; J Brazard; F Lacombat; P Plaza; M M Martin; G A Kraus; J W Petrich Chemical Physics Letters, 457 (1-3), p. 82–86, 2008. @article{Ley:2008, title = {Multiphotonic excitation and solvation dynamics effects on the femtosecond transient absorption of O-hexamethoxyhypericin}, author = {C Ley and J Brazard and F Lacombat and P Plaza and M M Martin and G A Kraus and J W Petrich}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-43549094927&doi=10.1016%2fj.cplett.2008.03.066&partnerID=40&md5=b5b213c38e5e9f6beff7cdfe2a3aa08b}, doi = {10.1016/j.cplett.2008.03.066}, year = {2008}, date = {2008-01-01}, journal = {Chemical Physics Letters}, volume = {457}, number = {1-3}, pages = {82--86}, abstract = {The hypothesis of a photoinduced intramolecular H-atom transfer in hypericin is reexamined by comparison with O-hexamethoxyhypericin, a derivative bearing no labile proton. In both cases, femtosecond transient absorption spectroscopy reveals an additional picosecond rising component in the kinetics under high excitation fluences. For the hexamethoxy derivative this effect is mixed with solvation dynamics but we succeeded in decoupling it. The delayed rise is ascribed to bi/multiphotonic excitation to upper excited states, followed by internal conversion to a hot S1 state that subsequently cools down. The present observations are not consistent with the intramolecular H-atom transfer interpretation. © 2008 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The hypothesis of a photoinduced intramolecular H-atom transfer in hypericin is reexamined by comparison with O-hexamethoxyhypericin, a derivative bearing no labile proton. In both cases, femtosecond transient absorption spectroscopy reveals an additional picosecond rising component in the kinetics under high excitation fluences. For the hexamethoxy derivative this effect is mixed with solvation dynamics but we succeeded in decoupling it. The delayed rise is ascribed to bi/multiphotonic excitation to upper excited states, followed by internal conversion to a hot S1 state that subsequently cools down. The present observations are not consistent with the intramolecular H-atom transfer interpretation. © 2008 Elsevier B.V. All rights reserved. |
Photoinduced intramolecular charge transfer in push-pull polyenes: Effects of solvation, electron-donor group, and polyenic chain length Article de journal W Akemann; D Laage; P Plaza; M M Martin; M Blanchard-Desce Journal of Physical Chemistry B, 112 (2), p. 358–368, 2008. @article{Akemann:2008, title = {Photoinduced intramolecular charge transfer in push-pull polyenes: Effects of solvation, electron-donor group, and polyenic chain length}, author = {W Akemann and D Laage and P Plaza and M M Martin and M Blanchard-Desce}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-38749115416&doi=10.1021%2fjp075418z&partnerID=40&md5=bcc70b3649484de02d0eb2a114c93a58}, doi = {10.1021/jp075418z}, year = {2008}, date = {2008-01-01}, journal = {Journal of Physical Chemistry B}, volume = {112}, number = {2}, pages = {358--368}, abstract = {Subpicosecond absorption spectroscopy is used to characterize the primary photoinduced processes in a class of push-pull polyenes bearing a julolidine end group as the electron donor and a diethylthiobarbituric acid end group as the electron acceptor. The excited-state decay time and relaxation pathway have been studied for four polyenes of increasing chain length (n = 2-5 double bonds) in aprotic solvents of different solvation time, polarity, and viscosity. Intramolecular charge transfer (ICT) leading to a transient state of cyanine-like structure (fully conjugated with no bond length alternation) is observed in all polar solvents at a solvent dependent rate, but the reaction is not observed in cyclohexane, a nonpolar solvent. In polar solvents, the reaction time increases with the average solvation time but remains slightly larger, except in the viscous solvent triacetin. These facts are interpreted as an indication that both solvent reorganization and internal restructuring are involved in the ICT-state formation. The observed photodynamics resemble those we previously found for another class of polyenes bearing a dibutylaniline group as the donor, including a similar charge-transfer rate in spite of the larger electron donor character of the julolidine group. This observation brings further support to the proposal that an intramolecular coordinate is involved in the charge-transfer reaction, possibly a torsional motion of the donor end group. On the other hand, relaxation of the ICT state leads to cis-trans isomerization or crossing to the triplet state, depending on the length of the polyenic chain. In dioxane, tetrahydrofuran, and triacetin, the ICT state of the shorter chains (n = 2, 3) relaxes to the isomer with a viscosity-dependent rate, while that of the longer ones (n = 4, 5) leads to the triplet state with a viscosity-independent rate, as expected. In acetonitrile, the ICT-state lifetime is generally much shorter. A change from photoisomerization to intersystem crossing at n = 4 is also proposed in this solvent, but the formation of a photoproduct at n = 2 is not clear. In cyclohexane, where the ICT state is not formed, the relaxation pathway of the initially excited state is found to lead to an isomer for n = 2. As in polar solvents, a change to intersystem crossing at n = 4 is proposed. The direct relaxation to the ground state found at n = 3 for the series bearing a dibutylaniline group is not observed with the julolidine group. The results clearly illustrate that photoinduced reaction trajectories in push-pull polyenes are controlled by the static and dynamic properties of the solvent, the chemical nature and size of the end groups, and the conjugated-chain length and flexibility. © 2008 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Subpicosecond absorption spectroscopy is used to characterize the primary photoinduced processes in a class of push-pull polyenes bearing a julolidine end group as the electron donor and a diethylthiobarbituric acid end group as the electron acceptor. The excited-state decay time and relaxation pathway have been studied for four polyenes of increasing chain length (n = 2-5 double bonds) in aprotic solvents of different solvation time, polarity, and viscosity. Intramolecular charge transfer (ICT) leading to a transient state of cyanine-like structure (fully conjugated with no bond length alternation) is observed in all polar solvents at a solvent dependent rate, but the reaction is not observed in cyclohexane, a nonpolar solvent. In polar solvents, the reaction time increases with the average solvation time but remains slightly larger, except in the viscous solvent triacetin. These facts are interpreted as an indication that both solvent reorganization and internal restructuring are involved in the ICT-state formation. The observed photodynamics resemble those we previously found for another class of polyenes bearing a dibutylaniline group as the donor, including a similar charge-transfer rate in spite of the larger electron donor character of the julolidine group. This observation brings further support to the proposal that an intramolecular coordinate is involved in the charge-transfer reaction, possibly a torsional motion of the donor end group. On the other hand, relaxation of the ICT state leads to cis-trans isomerization or crossing to the triplet state, depending on the length of the polyenic chain. In dioxane, tetrahydrofuran, and triacetin, the ICT state of the shorter chains (n = 2, 3) relaxes to the isomer with a viscosity-dependent rate, while that of the longer ones (n = 4, 5) leads to the triplet state with a viscosity-independent rate, as expected. In acetonitrile, the ICT-state lifetime is generally much shorter. A change from photoisomerization to intersystem crossing at n = 4 is also proposed in this solvent, but the formation of a photoproduct at n = 2 is not clear. In cyclohexane, where the ICT state is not formed, the relaxation pathway of the initially excited state is found to lead to an isomer for n = 2. As in polar solvents, a change to intersystem crossing at n = 4 is proposed. The direct relaxation to the ground state found at n = 3 for the series bearing a dibutylaniline group is not observed with the julolidine group. The results clearly illustrate that photoinduced reaction trajectories in push-pull polyenes are controlled by the static and dynamic properties of the solvent, the chemical nature and size of the end groups, and the conjugated-chain length and flexibility. © 2008 American Chemical Society. |
Polarized Transient Absorption to Resolve Electron Transfer between Tryptophans in DNA Photolyase Article de journal M Byrdin; S Villette; A Espagne; A P M Eker; K Brettel Journal of Physical Chemistry B, 112 (22), p. 6866-6871, 2008, ISSN: 1520-6106. @article{RN33b, title = {Polarized Transient Absorption to Resolve Electron Transfer between Tryptophans in DNA Photolyase}, author = {M Byrdin and S Villette and A Espagne and A P M Eker and K Brettel}, doi = {10.1021/jp711435y}, issn = {1520-6106}, year = {2008}, date = {2008-01-01}, journal = {Journal of Physical Chemistry B}, volume = {112}, number = {22}, pages = {6866-6871}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Primary photoprocesses involved in the sensory protein for the photophobie response of Blepharisma japonicum Article de journal J Brazard; C Ley; F Lacombat; P Plaza; M M Martin; G Checcucci; F Lenci Journal of Physical Chemistry B, 112 (47), p. 15182–15194, 2008. @article{Brazard:2008, title = {Primary photoprocesses involved in the sensory protein for the photophobie response of Blepharisma japonicum}, author = {J Brazard and C Ley and F Lacombat and P Plaza and M M Martin and G Checcucci and F Lenci}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-57449093150&doi=10.1021%2fjp805815e&partnerID=40&md5=e50debedfb440878c5edd474d3c3cd96}, doi = {10.1021/jp805815e}, year = {2008}, date = {2008-01-01}, journal = {Journal of Physical Chemistry B}, volume = {112}, number = {47}, pages = {15182--15194}, abstract = {We present new femtosecond transient-absorption and picosecond fluorescence experiments performed on OBIP, the oxyblepharismin-binding protein believed to trigger the Photophobie response of the ciliatc Blepharisma japonicum. The formerly identified heterogeneity of the sample is confirmed and rationalized in terms of two independent populations, called rOBlP and nrOBIP. The rOBIP population undergoes a fast photocycle restoring the initial ground state in less than 500 ps. Intermolecular electron transfer followed by electron recombination is identified as the excited-state decay route. The experimental results support the coexistence of the oxyblepharismin (OxyBP) radical cation signature with a stimulated-emission signal at all times of the evolution of the transient-absorption spectra. This observation is interpreted by an equilibrium being reached between the locally excited state and a charge-transfer state on the ground of a theory developed by Mataga and co-workers to explain the fluorescence quenching of aromatic hydrogen-bonded donor-acceptor pairs in nonpolar solvents. OxyBP is supposed to bind to an as yet unknown electron acceptor by a hydrogen-bond (HB) and the coordinate along which forward and backward electron transfer proceed is assumed to be the shift of the HB proton. The observed kinetic isotope effect supports this interpretation. Protein relaxation is finally proposed to accompany the whole process and give rise to the highly multiexponential observed dynamics. As previously reported, the fast photocycle of rOBIP can be interpreted as an efficient sunscreen mechanism that protects Blepharisma japonicum from continuous irradiation. The nrOBIP population, the transient-absorption of which strongly reminds that of free OxyBP in solution, might be proposed to actually trigger the Photophobie response of the organism through excited-state deprotonation of the chromophorc occurring in the nanosecond regime. Additional femtosecond transient-absorption spectra of OxyBP and perideprotonated OxyBP are also reported and used as a comparison basis to interpret the results on OBIP. © 2008 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present new femtosecond transient-absorption and picosecond fluorescence experiments performed on OBIP, the oxyblepharismin-binding protein believed to trigger the Photophobie response of the ciliatc Blepharisma japonicum. The formerly identified heterogeneity of the sample is confirmed and rationalized in terms of two independent populations, called rOBlP and nrOBIP. The rOBIP population undergoes a fast photocycle restoring the initial ground state in less than 500 ps. Intermolecular electron transfer followed by electron recombination is identified as the excited-state decay route. The experimental results support the coexistence of the oxyblepharismin (OxyBP) radical cation signature with a stimulated-emission signal at all times of the evolution of the transient-absorption spectra. This observation is interpreted by an equilibrium being reached between the locally excited state and a charge-transfer state on the ground of a theory developed by Mataga and co-workers to explain the fluorescence quenching of aromatic hydrogen-bonded donor-acceptor pairs in nonpolar solvents. OxyBP is supposed to bind to an as yet unknown electron acceptor by a hydrogen-bond (HB) and the coordinate along which forward and backward electron transfer proceed is assumed to be the shift of the HB proton. The observed kinetic isotope effect supports this interpretation. Protein relaxation is finally proposed to accompany the whole process and give rise to the highly multiexponential observed dynamics. As previously reported, the fast photocycle of rOBIP can be interpreted as an efficient sunscreen mechanism that protects Blepharisma japonicum from continuous irradiation. The nrOBIP population, the transient-absorption of which strongly reminds that of free OxyBP in solution, might be proposed to actually trigger the Photophobie response of the organism through excited-state deprotonation of the chromophorc occurring in the nanosecond regime. Additional femtosecond transient-absorption spectra of OxyBP and perideprotonated OxyBP are also reported and used as a comparison basis to interpret the results on OBIP. © 2008 American Chemical Society. |
Reactivity and Antiproliferative Activity of Ferrocenyl-Tamoxifen Adducts with Cyclodextrins against Hormone-Independent Breast-Cancer Cell Lines Article de journal Olivier Buriez; Jan Martin Heldt; Eric Labbe; Anne Vessieres; Gerard Jaouen; Christian Amatore Chemistry-a European Journal, 14 (27), p. 8195-8203, 2008. @article{RID:0721150706479-10, title = {Reactivity and Antiproliferative Activity of Ferrocenyl-Tamoxifen Adducts with Cyclodextrins against Hormone-Independent Breast-Cancer Cell Lines}, author = {Olivier Buriez and Jan Martin Heldt and Eric Labbe and Anne Vessieres and Gerard Jaouen and Christian Amatore}, year = {2008}, date = {2008-01-01}, journal = {Chemistry-a European Journal}, volume = {14}, number = {27}, pages = {8195-8203}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Real-time probing of fast photoinduced charge-transfer in electron donor-acceptor model compounds and in biological photosensors Article de journal M M Martin; P Plaza; P Changenet-Barret Polish Journal of Chemistry, 82 (4), p. 759-771, 2008, ISSN: 0137-5083. @article{RN58, title = {Real-time probing of fast photoinduced charge-transfer in electron donor-acceptor model compounds and in biological photosensors}, author = {M M Martin and P Plaza and P Changenet-Barret}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-42649142889&partnerID=40&md5=93d132ea839d81faa18476dd4eaaf617}, issn = {0137-5083}, year = {2008}, date = {2008-01-01}, journal = {Polish Journal of Chemistry}, volume = {82}, number = {4}, pages = {759-771}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Steady-state and femtosecond photoinduced processes of blepharismins bound to alpha-crystallin Article de journal T Youssef; J Brazard; C Ley; F Lacombat; P Plaza; M M Martin; A Sgarbossa; G Checcucci; F Lenci Photochemical and Photobiological Sciences, 7 (7), p. 844–853, 2008. @article{Youssef:2008, title = {Steady-state and femtosecond photoinduced processes of blepharismins bound to alpha-crystallin}, author = {T Youssef and J Brazard and C Ley and F Lacombat and P Plaza and M M Martin and A Sgarbossa and G Checcucci and F Lenci}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-46449089636&doi=10.1039%2fb800848e&partnerID=40&md5=948e794e195f413bde104725b45524da}, doi = {10.1039/b800848e}, year = {2008}, date = {2008-01-01}, journal = {Photochemical and Photobiological Sciences}, volume = {7}, number = {7}, pages = {844--853}, abstract = {The interaction of blepharismin (BP) and oxyblepharismin (OxyBP) with bovine alpha-crystallin (BAC) has been studied both by steady-state and femtosecond spectroscopy, with the aim of assessing the possible phototoxicity of these compounds toward the eye tissues. We showed that these pigments form with BAC potentially harmful ground-state complexes, the dissociation constants of which have been estimated to be 6 ± 2 μmol L-1 for OxyBP and 9 ± 4 μmol L-1 for BP. Irradiation with steady-state visible light of solutions of blepharismins in the presence of BAC proved to induce a quenching of both the pigment and the intrinsic protein fluorescences. These effects were tentatively rationalized in terms of structural changes of alpha-crystallin. On the other hand, femtosecond transient absorption spectroscopy was used to check the occurrence of any type I photoactivity of oxyblepharismin bound to alpha-crystallin. The existence of a particular type of fast photoinduced reaction, not observed in former studies with human serum albumin but present in the natural oxyblepharismin-binding protein, could here be evidenced but no specific reaction was observed during the first few nanoseconds after excitation. Partial denaturation of alpha-crystallin was however found to alter the excited-state behaviour of its complex with oxyblepharismin, making it partly resemble that of free oxyblepharismin in solution. © The Royal Society of Chemistry and Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The interaction of blepharismin (BP) and oxyblepharismin (OxyBP) with bovine alpha-crystallin (BAC) has been studied both by steady-state and femtosecond spectroscopy, with the aim of assessing the possible phototoxicity of these compounds toward the eye tissues. We showed that these pigments form with BAC potentially harmful ground-state complexes, the dissociation constants of which have been estimated to be 6 ± 2 μmol L-1 for OxyBP and 9 ± 4 μmol L-1 for BP. Irradiation with steady-state visible light of solutions of blepharismins in the presence of BAC proved to induce a quenching of both the pigment and the intrinsic protein fluorescences. These effects were tentatively rationalized in terms of structural changes of alpha-crystallin. On the other hand, femtosecond transient absorption spectroscopy was used to check the occurrence of any type I photoactivity of oxyblepharismin bound to alpha-crystallin. The existence of a particular type of fast photoinduced reaction, not observed in former studies with human serum albumin but present in the natural oxyblepharismin-binding protein, could here be evidenced but no specific reaction was observed during the first few nanoseconds after excitation. Partial denaturation of alpha-crystallin was however found to alter the excited-state behaviour of its complex with oxyblepharismin, making it partly resemble that of free oxyblepharismin in solution. © The Royal Society of Chemistry and Owner Societies. |
Supramolecular effects of cyclodextrins on the electrochemical reduction and reactivity of aromatic carbonyl compounds Article de journal Christian Amatore; Olivier Buriez; Eric Labbe; Jean-Noel Verpeaux Journal of Electroanalytical Chemistry, 621 (2), p. 134-145, 2008. @article{RID:0721150706479-14, title = {Supramolecular effects of cyclodextrins on the electrochemical reduction and reactivity of aromatic carbonyl compounds}, author = {Christian Amatore and Olivier Buriez and Eric Labbe and Jean-Noel Verpeaux}, year = {2008}, date = {2008-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {621}, number = {2}, pages = {134-145}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Ultrafast photochemical processes: From the lab to natural photoactive systems Article de journal M M Martin; P Plaza; P Changenet-Barret; A Espagne; M Mahet; C Ley; F Lacombat Actualite Chimique, (320-321), p. 14–19, 2008. @article{Martin:2008, title = {Ultrafast photochemical processes: From the lab to natural photoactive systems}, author = {M M Martin and P Plaza and P Changenet-Barret and A Espagne and M Mahet and C Ley and F Lacombat}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-48649089855&partnerID=40&md5=5dbe5748299ea91b50952e61834a11b9}, year = {2008}, date = {2008-01-01}, journal = {Actualite Chimique}, number = {320-321}, pages = {14--19}, abstract = {The UV-Vis subpicosecond absorption spectroscopy has been used to characterize and probe in real-time the primary photoinduced chemical processes in two photosensory proteins extracted from photomotile micro-organisms. This approach to the structure-function relationship of these photoactive proteins consists in comparing their photophysics to that of their chromophore isolated in solution, in order to evidence the specificity of the natural chromophore-protein complex. It has been shown that the photoisomerisation kinetic and quantum yield of the chromophore of photoactive yellow protein (PYP) are controlled by the properties of the protein nanospace in which it is embedded, and also that the oxyblepharism binding protein (OBIP) undergoes photoinduced picosecond reactions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The UV-Vis subpicosecond absorption spectroscopy has been used to characterize and probe in real-time the primary photoinduced chemical processes in two photosensory proteins extracted from photomotile micro-organisms. This approach to the structure-function relationship of these photoactive proteins consists in comparing their photophysics to that of their chromophore isolated in solution, in order to evidence the specificity of the natural chromophore-protein complex. It has been shown that the photoisomerisation kinetic and quantum yield of the chromophore of photoactive yellow protein (PYP) are controlled by the properties of the protein nanospace in which it is embedded, and also that the oxyblepharism binding protein (OBIP) undergoes photoinduced picosecond reactions. |
2007 |
Activation of 1-halonaphthalenes by electrogenerated Co-I-salen (-) Article de journal Nadge Faux; Eric Labbe; Olivier Buriez; Jean Yves Nedelec Journal of Electroanalytical Chemistry, 600 (2), p. 359-363, 2007. @article{RID:0721150706479-5, title = {Activation of 1-halonaphthalenes by electrogenerated Co-I-salen (-)}, author = {Nadge Faux and Eric Labbe and Olivier Buriez and Jean Yves Nedelec}, year = {2007}, date = {2007-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {600}, number = {2}, pages = {359-363}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Cellular photoperception and photoactive proteins Article de journal M Martin; S Haacke; M Chergui; P Plaza; P Changenet-Barret; K Brettel; M Byrdin; J Y Bigot; L Guidoni; P Didier Actualité Chimique, 308-309 , p. 19-24, 2007, ISSN: 0151-9093. @article{RN54, title = {Cellular photoperception and photoactive proteins}, author = {M Martin and S Haacke and M Chergui and P Plaza and P Changenet-Barret and K Brettel and M Byrdin and J Y Bigot and L Guidoni and P Didier}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-34547297831&origin=resultslist&sort=plf-f&cite=2-s2.0-85005697420&src=s&imp=t&sid=4bf7c1307b95cbc645e86552103ccc27&sot=cite&sdt=a&sl=0&relpos=18&citeCnt=0&searchTerm=}, issn = {0151-9093}, year = {2007}, date = {2007-01-01}, journal = {Actualit\'{e} Chimique}, volume = {308-309}, pages = {19-24}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Changes in the Morphology of Giant Vesicles Under Various Physico-Chemical Stresses incollection M -A Guedeau-Boudeville; A -L Bernard; J Bradley; A Singh; L Jullien Giant Vesicles: Perspectives in Supramolecular Chemistry, 6 , p. 341–349, 2007. @incollection{Guedeau-Boudeville:2007, title = {Changes in the Morphology of Giant Vesicles Under Various Physico-Chemical Stresses}, author = {M -A Guedeau-Boudeville and A -L Bernard and J Bradley and A Singh and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955368046&doi=10.1002%2f9780470511534.ch26&partnerID=40&md5=630542a3e134f9fe44a60c1a944d2643}, doi = {10.1002/9780470511534.ch26}, year = {2007}, date = {2007-01-01}, booktitle = {Giant Vesicles: Perspectives in Supramolecular Chemistry}, volume = {6}, pages = {341--349}, keywords = {}, pubstate = {published}, tppubtype = {incollection} } |
Chemical Probes Shed Light on Protein Function Article de journal Helen M O'Hare; Kai Johnsson; Arnaud Gautier Current Opinion in Structural Biology, 17 (4), p. 488-494, 2007, ISSN: 0959-440X. @article{RN46, title = {Chemical Probes Shed Light on Protein Function}, author = {Helen M O'Hare and Kai Johnsson and Arnaud Gautier}, doi = {https://doi.org/10.1016/j.sbi.2007.07.005}, issn = {0959-440X}, year = {2007}, date = {2007-01-01}, journal = {Current Opinion in Structural Biology}, volume = {17}, number = {4}, pages = {488-494}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Comparison of apex and bottom secretion efficiency at chromaffin cells as measured by amperometry Article de journal C Amatore; S Arbault; F Lemaître; Y Verchier Biophysical Chemistry, 127 (3), p. 165–171, 2007. @article{Amatore:2007a, title = {Comparison of apex and bottom secretion efficiency at chromaffin cells as measured by amperometry}, author = {C Amatore and S Arbault and F Lema\^{i}tre and Y Verchier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947329500&doi=10.1016%2fj.bpc.2007.01.007&partnerID=40&md5=2cf451e422357961982f90bcbe7697e3}, doi = {10.1016/j.bpc.2007.01.007}, year = {2007}, date = {2007-01-01}, journal = {Biophysical Chemistry}, volume = {127}, number = {3}, pages = {165--171}, abstract = {In chromaffin cells, the exocytosis of neuromediators involves the fusion between a secretory vesicle and the cell membrane. Many techniques based on electrophysiology, electrochemistry and fluorescence microscopy allow the study of such a complex process at active zones of single immobilized cells. These techniques can provide an effective analysis either at the apex, either at the base of the cell adhering onto a substrate. For instance, patch-clamp (electrophysiology) and amperometry (electrochemistry) deal with detection at the exposed top of the cell, whereas evanescent field microscopy concerns mainly its bottom, i.e., the zone on which the cell rests onto the surface. However, in chromaffin cells, comparison between the two sets of methods remains to be established and whether apex fusion events are comparable or not to those observed at the base of the cell is an open question. In this work, we compare both active zones upon using the same measurement method, viz., by performing electrochemical detection at these both poles (top and bottom) of bovine chromaffin cells. This is performed upon using carbon fiber microelectrodes (apical analysis) and planar ITO transparent (basal analysis) electrodes, respectively. Our results indicate that the processes monitored at each pole differ though the same technique is used. © 2007 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In chromaffin cells, the exocytosis of neuromediators involves the fusion between a secretory vesicle and the cell membrane. Many techniques based on electrophysiology, electrochemistry and fluorescence microscopy allow the study of such a complex process at active zones of single immobilized cells. These techniques can provide an effective analysis either at the apex, either at the base of the cell adhering onto a substrate. For instance, patch-clamp (electrophysiology) and amperometry (electrochemistry) deal with detection at the exposed top of the cell, whereas evanescent field microscopy concerns mainly its bottom, i.e., the zone on which the cell rests onto the surface. However, in chromaffin cells, comparison between the two sets of methods remains to be established and whether apex fusion events are comparable or not to those observed at the base of the cell is an open question. In this work, we compare both active zones upon using the same measurement method, viz., by performing electrochemical detection at these both poles (top and bottom) of bovine chromaffin cells. This is performed upon using carbon fiber microelectrodes (apical analysis) and planar ITO transparent (basal analysis) electrodes, respectively. Our results indicate that the processes monitored at each pole differ though the same technique is used. © 2007 Elsevier B.V. All rights reserved. |
Electrochemical activation of β-lapachone in β-cyclodextrin inclusion complexes and reactivity of its reduced form towards oxygen in aqueous solutions Article de journal F C de Abreu; D C M Ferreira; M O F Goulart; O Buriez; C Amatore Journal of Electroanalytical Chemistry, 608 (2), p. 125–132, 2007. @article{deAbreu:2007, title = {Electrochemical activation of β-lapachone in β-cyclodextrin inclusion complexes and reactivity of its reduced form towards oxygen in aqueous solutions}, author = {F C de Abreu and D C M Ferreira and M O F Goulart and O Buriez and C Amatore}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548644479&doi=10.1016%2fj.jelechem.2007.05.020&partnerID=40&md5=8ed62bd89e5795ebf0a17117cd46d1dc}, doi = {10.1016/j.jelechem.2007.05.020}, year = {2007}, date = {2007-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {608}, number = {2}, pages = {125--132}, abstract = {β-Lapachone (1) is a natural ortho-naphthoquinone that has been shown to have a variety of pharmacological effects, mainly anticancer activity. As a single agent, β-lapachone has demonstrated significant antineoplastic activity against several human cancer cell lines at concentrations typically in the range of 1-10 μM (IC50). The use of cyclodextrins is useful to overcome solubility and bioavailability problems. In the present case, cyclic voltammetry and UV/vis spectroscopy have been used to monitor the inclusion phenomena of β-lapachone within the cavity of β-cyclodextrin, together with studies concerning the competitive effects of ethanol concentration on this behavior. A value of 15 ± 5 M-1 was found for the association constant between β-lapachone and β-cyclodextrin in phosphate buffer, in the presence of 5% ethanol. The electrochemical behavior of the β-lapachone reduced form suggests external interactions between the hydroquinone and β-cyclodextrin via the formation of hydrogen bonds. Electrochemical studies were also performed in the presence of oxygen, since the redox environment of β-lapachone biological targets is considered very important for its therapeutical efficiency. In the presence of O2, β-lapachone has shown a catalytic reduction wave, related probably to an electron transfer to oxygen, generating oxygen reactive species and giving back the parent quinone, leading thus to a redox cycle, with a kinetic apparent constant of 40 s-1. These in vitro results correlate with in vivo activities. © 2007 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } β-Lapachone (1) is a natural ortho-naphthoquinone that has been shown to have a variety of pharmacological effects, mainly anticancer activity. As a single agent, β-lapachone has demonstrated significant antineoplastic activity against several human cancer cell lines at concentrations typically in the range of 1-10 μM (IC50). The use of cyclodextrins is useful to overcome solubility and bioavailability problems. In the present case, cyclic voltammetry and UV/vis spectroscopy have been used to monitor the inclusion phenomena of β-lapachone within the cavity of β-cyclodextrin, together with studies concerning the competitive effects of ethanol concentration on this behavior. A value of 15 ± 5 M-1 was found for the association constant between β-lapachone and β-cyclodextrin in phosphate buffer, in the presence of 5% ethanol. The electrochemical behavior of the β-lapachone reduced form suggests external interactions between the hydroquinone and β-cyclodextrin via the formation of hydrogen bonds. Electrochemical studies were also performed in the presence of oxygen, since the redox environment of β-lapachone biological targets is considered very important for its therapeutical efficiency. In the presence of O2, β-lapachone has shown a catalytic reduction wave, related probably to an electron transfer to oxygen, generating oxygen reactive species and giving back the parent quinone, leading thus to a redox cycle, with a kinetic apparent constant of 40 s-1. These in vitro results correlate with in vivo activities. © 2007 Elsevier B.V. All rights reserved. |
Electrochemical aerobic oxidation of aminocyclopropanes to endoperoxides Article de journal C Madelaine; Y Six; O Buriez Angewandte Chemie - International Edition, 46 (42), p. 8046–8049, 2007. @article{Madelaine:2007, title = {Electrochemical aerobic oxidation of aminocyclopropanes to endoperoxides}, author = {C Madelaine and Y Six and O Buriez}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-35649020765&doi=10.1002%2fanie.200702903&partnerID=40&md5=3fcf75ce883463516bde923eb9437745}, doi = {10.1002/anie.200702903}, year = {2007}, date = {2007-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {46}, number = {42}, pages = {8046--8049}, abstract = {(Chemical Equation Presented) Electrical synthesizer: Results of cyclic voltammetric studies on a range of aminocyclopropanes in the absence or in the presence of oxygen are in full agreement with the currently accepted autocatalytic mechanism for the aerobic oxidation of these compounds. A simple and efficient procedure was developed for the electrosynthesis of the corresponding endoperoxides (see scheme), some of which exhibit moderate antimalarial activity. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } (Chemical Equation Presented) Electrical synthesizer: Results of cyclic voltammetric studies on a range of aminocyclopropanes in the absence or in the presence of oxygen are in full agreement with the currently accepted autocatalytic mechanism for the aerobic oxidation of these compounds. A simple and efficient procedure was developed for the electrosynthesis of the corresponding endoperoxides (see scheme), some of which exhibit moderate antimalarial activity. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
Fourier analysis to measure diffusion coefficients and resolve mixtures on a continuous electrophoresis chip Article de journal A Estévez-Torres; C Gosse; T Le Saux; J -F Allemand; V Croquette; H Berthoumieux; A Lemarchand; L Jullien Analytical Chemistry, 79 (21), p. 8222–8231, 2007. @article{Estevez-Torres:2007, title = {Fourier analysis to measure diffusion coefficients and resolve mixtures on a continuous electrophoresis chip}, author = {A Est\'{e}vez-Torres and C Gosse and T Le Saux and J -F Allemand and V Croquette and H Berthoumieux and A Lemarchand and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-35848961243&doi=10.1021%2fac070532z&partnerID=40&md5=a7d83124bd11f49b053fcdce6e8e4fcf}, doi = {10.1021/ac070532z}, year = {2007}, date = {2007-01-01}, journal = {Analytical Chemistry}, volume = {79}, number = {21}, pages = {8222--8231}, abstract = {We report a method to measure diffusion coefficients of fluorescent solutes in the 102-106 Da molecular mass range in a glass-PDMS chip. Upon applying a permanent electric field, the solute is introduced through a narrow channel into a wide analysis chamber where it migrates along the injection axis and diffuses in two dimensions. The diffusion coefficient is extracted after 1D Fourier transform of the resulting stationary concentration pattern. Analysis is straightforward, requiring no numerical integration or velocity field simulation. The diffusion coefficients measured for fluorescein, rhodamine green-labeled oligonucleotides, and YOYO-1-stained dsDNA fragments agree with the literature values and with our own fluorescence correlation spectroscopy measurements. As shown for 151 and 1257 base pair dsDNA mixtures, the present method allows us to rely on diffusion to quantitatively characterize the nature and the composition of binary mixtures. In particular, we implement a DNA hybridization assay to illustrate the efficiency of the proposed protocol for library screening. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report a method to measure diffusion coefficients of fluorescent solutes in the 102-106 Da molecular mass range in a glass-PDMS chip. Upon applying a permanent electric field, the solute is introduced through a narrow channel into a wide analysis chamber where it migrates along the injection axis and diffuses in two dimensions. The diffusion coefficient is extracted after 1D Fourier transform of the resulting stationary concentration pattern. Analysis is straightforward, requiring no numerical integration or velocity field simulation. The diffusion coefficients measured for fluorescein, rhodamine green-labeled oligonucleotides, and YOYO-1-stained dsDNA fragments agree with the literature values and with our own fluorescence correlation spectroscopy measurements. As shown for 151 and 1257 base pair dsDNA mixtures, the present method allows us to rely on diffusion to quantitatively characterize the nature and the composition of binary mixtures. In particular, we implement a DNA hybridization assay to illustrate the efficiency of the proposed protocol for library screening. © 2007 American Chemical Society. |
Photoinduced charge shift as the driving force for the excited-state relaxation of analogues of the Photoactive Yellow Protein chromophore in solution Article de journal A Espagne; P Changenet-Barret; J -B Baudin; P Plaza; M M Martin Journal of Photochemistry and Photobiology A: Chemistry, 185 (2-3), p. 245-252, 2007, ISSN: 1010-6030. @article{RN51, title = {Photoinduced charge shift as the driving force for the excited-state relaxation of analogues of the Photoactive Yellow Protein chromophore in solution}, author = {A Espagne and P Changenet-Barret and J -B Baudin and P Plaza and M M Martin}, url = {<Go to ISI>://000243736600019}, doi = {10.1016/j.jphotochem.2006.06.016}, issn = {1010-6030}, year = {2007}, date = {2007-01-01}, journal = {Journal of Photochemistry and Photobiology A: Chemistry}, volume = {185}, number = {2-3}, pages = {245-252}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Primary photoprocesses in oxyblepharismin interacting with its native protein partner Article de journal M Mahet; P Plaza; M M Martin; G Checcucci; F Lenci Journal of Photochemistry and Photobiology A: Chemistry, 185 (2-3), p. 345–353, 2007. @article{Mahet:2007, title = {Primary photoprocesses in oxyblepharismin interacting with its native protein partner}, author = {M Mahet and P Plaza and M M Martin and G Checcucci and F Lenci}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845674602&doi=10.1016%2fj.jphotochem.2006.06.030&partnerID=40&md5=292f9acdb239c0f7be41d6344b5be148}, doi = {10.1016/j.jphotochem.2006.06.030}, year = {2007}, date = {2007-01-01}, journal = {Journal of Photochemistry and Photobiology A: Chemistry}, volume = {185}, number = {2-3}, pages = {345--353}, abstract = {The primary photoprocesses in the photoreceptor for the step-up photophobic response of the light-adapted cells of Blepharisma japonicum (OBIP, OxyBlepharismin bInding Protein) have been studied by ultrafast UV-vis transient spectroscopy. The results are rationalized in terms of heterogeneity of the OBIP sample. Two independent classes of chromoprotein are proposed: a "reactive" species, which presents a specific 680-nm band decaying in 4 and 56 ps and a "non-reactive" one, which behaves like the free chromophore (OxyBP) in solution. A bimolecular photooxidation of OxyBP in the presence of 1,4-benzoquinone was performed to record the absorption spectrum of the OxyBP radical cation. Comparison with reactive OBIP suggests that an electron transfer could be involved in the primary photoprocesses of OBIP and possibly trigger the sensory transduction chain of B. japonicum. In addition, the specificity of the chromophore-protein interaction was investigated by studying the artificial complex that OxyBP forms with human serum albumin (HSA). OxyBP-HSA happens to be spectroscopically much closer to free OxyBP than to OBIP. This highlights the specific nature of the interaction between OxyBP and its native protein partner and further supports the proposal that OBIP is the actual photoreceptor for the photophobic response of B. japonicum. © 2006 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The primary photoprocesses in the photoreceptor for the step-up photophobic response of the light-adapted cells of Blepharisma japonicum (OBIP, OxyBlepharismin bInding Protein) have been studied by ultrafast UV-vis transient spectroscopy. The results are rationalized in terms of heterogeneity of the OBIP sample. Two independent classes of chromoprotein are proposed: a "reactive" species, which presents a specific 680-nm band decaying in 4 and 56 ps and a "non-reactive" one, which behaves like the free chromophore (OxyBP) in solution. A bimolecular photooxidation of OxyBP in the presence of 1,4-benzoquinone was performed to record the absorption spectrum of the OxyBP radical cation. Comparison with reactive OBIP suggests that an electron transfer could be involved in the primary photoprocesses of OBIP and possibly trigger the sensory transduction chain of B. japonicum. In addition, the specificity of the chromophore-protein interaction was investigated by studying the artificial complex that OxyBP forms with human serum albumin (HSA). OxyBP-HSA happens to be spectroscopically much closer to free OxyBP than to OBIP. This highlights the specific nature of the interaction between OxyBP and its native protein partner and further supports the proposal that OBIP is the actual photoreceptor for the photophobic response of B. japonicum. © 2006 Elsevier B.V. All rights reserved. |
Rate and mechanism of the Heck reactions of arylpalladium complexes ligated by a bidentate P,P ligand with an electron-rich alkene (isobutyl vinyl ether) Article de journal C Amatore; B Godin; A Jutand; F Lemaître Organometallics, 26 (7), p. 1757–1761, 2007. @article{Amatore:2007m, title = {Rate and mechanism of the Heck reactions of arylpalladium complexes ligated by a bidentate P,P ligand with an electron-rich alkene (isobutyl vinyl ether)}, author = {C Amatore and B Godin and A Jutand and F Lema\^{i}tre}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34047269783&doi=10.1021%2fom0610849&partnerID=40&md5=2a491d504169e86693a654879673a004}, doi = {10.1021/om0610849}, year = {2007}, date = {2007-01-01}, journal = {Organometallics}, volume = {26}, number = {7}, pages = {1757--1761}, abstract = {Two main intermediate complexes, PhPd(OAc)(dppp) and PhPdI(dppp), are generated in palladium-catalyzed Heck reactions performed from Phi and an acetate salt used as a base, in DMF. Both complexes react with the electron-rich alkene isobutyl vinyl ether (CH2=CHOiBu) exclusively by an ionic mechanism, i.e., via the cationic complex [PhPd(dppp)(DMF)]+ formed by dissociation of AcO- or I- from the parent complexes, as already established for the reaction of PhPd(OAc)(dppp) with styrene and methyl acrylate and the reaction of PhPdI(dppp) with styrene. A mechanism is proposed which rationalizes the regioselectivity observed when reacting the electron-rich isobutylvinyl ether in palladium-catalyzed Heck reactions. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two main intermediate complexes, PhPd(OAc)(dppp) and PhPdI(dppp), are generated in palladium-catalyzed Heck reactions performed from Phi and an acetate salt used as a base, in DMF. Both complexes react with the electron-rich alkene isobutyl vinyl ether (CH2=CHOiBu) exclusively by an ionic mechanism, i.e., via the cationic complex [PhPd(dppp)(DMF)]+ formed by dissociation of AcO- or I- from the parent complexes, as already established for the reaction of PhPd(OAc)(dppp) with styrene and methyl acrylate and the reaction of PhPdI(dppp) with styrene. A mechanism is proposed which rationalizes the regioselectivity observed when reacting the electron-rich isobutylvinyl ether in palladium-catalyzed Heck reactions. © 2007 American Chemical Society. |
Rate and mechanism of the reaction of alkenes with aryl palladium complexes ligated by a bidentate P,P ligand in heck reactions Article de journal C Amatore; B Godin; A Jutand; F Lemaître Chemistry - A European Journal, 13 (7), p. 2002–2011, 2007. @article{Amatore:2007l, title = {Rate and mechanism of the reaction of alkenes with aryl palladium complexes ligated by a bidentate P,P ligand in heck reactions}, author = {C Amatore and B Godin and A Jutand and F Lema\^{i}tre}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34047255523&doi=10.1002%2fchem.200600153&partnerID=40&md5=e35f1944755f6ed53bb8c914de847d02}, doi = {10.1002/chem.200600153}, year = {2007}, date = {2007-01-01}, journal = {Chemistry - A European Journal}, volume = {13}, number = {7}, pages = {2002--2011}, abstract = {The regioselectivity of the Heck reaction is supposed to be highly affected by the electronic properties of the alkene and the ionic or neutral character of the aryl palladium(II) complexes involved in the reaction with alkenes. In Heck reactions performed in dmf. [Pd(dppp)-(dppp(O))Ph]+ (dppp= 1,2-bis(diphenylphosphino)propane) is generated in the oxidative addition of Phi with [Pd0-(dppp)(OAc)] formed in situ from Pd(OAc): associated to two equivalents of dppp. [Pd(dppp)jdppp(O))Ph]+ is not very reactive with alkenes (styrene or methyl acrylate); however, it reacts with iodide ions (released in the catalytic reactions) to give [Pd(dppp)IPh) and with acetate ions (used as base) to give [Pd(dppp)(OAc)Ph]. [Pd(dppp)-(OAc)Ph] reacts with styrene and methyl acrylate exclusively by an ionic mechanism, that is. via the cationic complex [Pd(dppp)(dmf)Ph]+ formed by dissociation of the acetate ion. The reaction of [Pd(dppp)IPh] is more complex and substrate dependent. It reacts with styrene exclusively by the ionic mechanism via [Pd(dppp)-(dmf)Ph]+. [Pd(dppp)IPh] (neutral mechanism) and [Pd(dppp)(dmf)Ph]+ (ionic mechanism) react in parallel with methyl acrylate. [Pd(dppp)-(dmf)Ph]+ is more reactive than [Pd-(dppp)IPh) but is always generated at lower concentration. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The regioselectivity of the Heck reaction is supposed to be highly affected by the electronic properties of the alkene and the ionic or neutral character of the aryl palladium(II) complexes involved in the reaction with alkenes. In Heck reactions performed in dmf. [Pd(dppp)-(dppp(O))Ph]+ (dppp= 1,2-bis(diphenylphosphino)propane) is generated in the oxidative addition of Phi with [Pd0-(dppp)(OAc)] formed in situ from Pd(OAc): associated to two equivalents of dppp. [Pd(dppp)jdppp(O))Ph]+ is not very reactive with alkenes (styrene or methyl acrylate); however, it reacts with iodide ions (released in the catalytic reactions) to give [Pd(dppp)IPh) and with acetate ions (used as base) to give [Pd(dppp)(OAc)Ph]. [Pd(dppp)-(OAc)Ph] reacts with styrene and methyl acrylate exclusively by an ionic mechanism, that is. via the cationic complex [Pd(dppp)(dmf)Ph]+ formed by dissociation of the acetate ion. The reaction of [Pd(dppp)IPh] is more complex and substrate dependent. It reacts with styrene exclusively by the ionic mechanism via [Pd(dppp)-(dmf)Ph]+. [Pd(dppp)IPh] (neutral mechanism) and [Pd(dppp)(dmf)Ph]+ (ionic mechanism) react in parallel with methyl acrylate. [Pd(dppp)-(dmf)Ph]+ is more reactive than [Pd-(dppp)IPh) but is always generated at lower concentration. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
Relationship between amperometric pre-spike feet and secretion granule composition in Chromaffin cells: An overview Article de journal C Amatore; S Arbault; I Bonifas; M Guille; F Lemaître; Y Verchier Biophysical Chemistry, 129 (2-3), p. 181–189, 2007. @article{Amatore:2007n, title = {Relationship between amperometric pre-spike feet and secretion granule composition in Chromaffin cells: An overview}, author = {C Amatore and S Arbault and I Bonifas and M Guille and F Lema\^{i}tre and Y Verchier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547560678&doi=10.1016%2fj.bpc.2007.05.018&partnerID=40&md5=c92376d4195c4dfec6edfd9e5eb98173}, doi = {10.1016/j.bpc.2007.05.018}, year = {2007}, date = {2007-01-01}, journal = {Biophysical Chemistry}, volume = {129}, number = {2-3}, pages = {181--189}, abstract = {Amperometry is a simple and powerful technique to study exocytosis at the single cell level. By positioning and polarizing (at an appropriate potential at which the molecules released by the cell can be oxidized) a carbon fiber microelectrode at the top of the cell, each exocytotic event is detected as an amperometric spike. More particularly, a portion of these spikes has previously been shown to present a foot, i.e. a small pedestal of current that precedes the spike itself. Among the important number of works dealing with the monitoring of exocytosis by amperometry under different conditions, only a few studies focus on amperometric spikes with a foot. In this work, by coupling our previous and recent experiments on chromaffin cells (that release catecholamines after stimulation) with literature data, we bring more light on what an amperometric foot and particularly its features, represents. © 2007.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Amperometry is a simple and powerful technique to study exocytosis at the single cell level. By positioning and polarizing (at an appropriate potential at which the molecules released by the cell can be oxidized) a carbon fiber microelectrode at the top of the cell, each exocytotic event is detected as an amperometric spike. More particularly, a portion of these spikes has previously been shown to present a foot, i.e. a small pedestal of current that precedes the spike itself. Among the important number of works dealing with the monitoring of exocytosis by amperometry under different conditions, only a few studies focus on amperometric spikes with a foot. In this work, by coupling our previous and recent experiments on chromaffin cells (that release catecholamines after stimulation) with literature data, we bring more light on what an amperometric foot and particularly its features, represents. © 2007. |
Role of arginine 52 on the primary photoinduced events in the PYP photocycle Article de journal P Changenet-Barret; P Plaza; M M Martin; H Chosrowjan; S Taniguchi; N Mataga; Y Imamoto; M Kataoka Chemical Physics Letters, 434 (4-6), p. 320–325, 2007. @article{Changenet-Barret:2007, title = {Role of arginine 52 on the primary photoinduced events in the PYP photocycle}, author = {P Changenet-Barret and P Plaza and M M Martin and H Chosrowjan and S Taniguchi and N Mataga and Y Imamoto and M Kataoka}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846203359&doi=10.1016%2fj.cplett.2006.12.027&partnerID=40&md5=63606ca56aff55ca2e30db6af88fa152}, doi = {10.1016/j.cplett.2006.12.027}, year = {2007}, date = {2007-01-01}, journal = {Chemical Physics Letters}, volume = {434}, number = {4-6}, pages = {320--325}, abstract = {We investigated the earliest steps of the photocycle of photoactive yellow protein (PYP) and its R52Q mutant in aqueous solution, by subpicosecond transient absorption spectroscopy. Our aim was to address the role of the positively charged Arg52 residue. We found that the relaxation mechanism of R52Q is similar to that of wt-PYP and discarded that Arg52 plays a key role in the chromophore photoreactivity. The excited-state decay of R52Q is however slower, confirming previous fluorescence up-conversion data. The experiments also reveal a slower stabilization of the cis isomer product. The loosening of the protein pocket and structural heterogeneities are discussed. © 2006 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the earliest steps of the photocycle of photoactive yellow protein (PYP) and its R52Q mutant in aqueous solution, by subpicosecond transient absorption spectroscopy. Our aim was to address the role of the positively charged Arg52 residue. We found that the relaxation mechanism of R52Q is similar to that of wt-PYP and discarded that Arg52 plays a key role in the chromophore photoreactivity. The excited-state decay of R52Q is however slower, confirming previous fluorescence up-conversion data. The experiments also reveal a slower stabilization of the cis isomer product. The loosening of the protein pocket and structural heterogeneities are discussed. © 2006 Elsevier B.V. All rights reserved. |
Target analysis of primary photoprocesses involved in the oxyblepharismin-binding protein Article de journal P Plaza; M Mahet; M M Martin; G Checcucci; F Lenci Journal of Physical Chemistry B, 111 (4), p. 690–696, 2007. @article{Plaza:2007, title = {Target analysis of primary photoprocesses involved in the oxyblepharismin-binding protein}, author = {P Plaza and M Mahet and M M Martin and G Checcucci and F Lenci}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33847050886&doi=10.1021%2fjp0642591&partnerID=40&md5=493aaa2ac98825d3cee9d4a879e14b4f}, doi = {10.1021/jp0642591}, year = {2007}, date = {2007-01-01}, journal = {Journal of Physical Chemistry B}, volume = {111}, number = {4}, pages = {690--696}, abstract = {Target analysis is performed on previously published transient absorption spectra of the 200-kDa oxyblepharismin-binding protein (OBIP) thought to trigger the photophobic response of the ciliate Blepharisma japonicum. The OBIP sample is considered as heterogeneous and made of two distinct classes of chromophore-protein complexes. A so-called nonreactive class is seen to be comparable to free oxyblepharismin in organic solution. Another, reactive, class is shown to undergo a fast picosecond photocycle involving the formation in 4 ps of an intermediate state noted Y1. The spectrum associated to Y1 bears striking similarities with that of the oxyblepharismin radical cation. This element favors the hypothesis that an excited-state intermolecular electron-transfer could be the primary step of the sensory transduction chain of B. japonicum. Proton release is also considered as a possible secondary step. These possibilities support the idea that reactive OBIP functions like an electron or proton pump. We alternatively propose a new hypothesis stating that the fast photocycle of reactive OBIP actually does not generate any photoproduct or protein change of conformation but is involved in another biological function. It would act as a kind of solar screen, providing additional protection to the light-adapted form of B. japonicum in case of excessive illumination. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Target analysis is performed on previously published transient absorption spectra of the 200-kDa oxyblepharismin-binding protein (OBIP) thought to trigger the photophobic response of the ciliate Blepharisma japonicum. The OBIP sample is considered as heterogeneous and made of two distinct classes of chromophore-protein complexes. A so-called nonreactive class is seen to be comparable to free oxyblepharismin in organic solution. Another, reactive, class is shown to undergo a fast picosecond photocycle involving the formation in 4 ps of an intermediate state noted Y1. The spectrum associated to Y1 bears striking similarities with that of the oxyblepharismin radical cation. This element favors the hypothesis that an excited-state intermolecular electron-transfer could be the primary step of the sensory transduction chain of B. japonicum. Proton release is also considered as a possible secondary step. These possibilities support the idea that reactive OBIP functions like an electron or proton pump. We alternatively propose a new hypothesis stating that the fast photocycle of reactive OBIP actually does not generate any photoproduct or protein change of conformation but is involved in another biological function. It would act as a kind of solar screen, providing additional protection to the light-adapted form of B. japonicum in case of excessive illumination. © 2007 American Chemical Society. |
Temporal modulation of a spatially periodic potential for kinetically governed oriented motion Article de journal H Berthoumieux; L Jullien; A Lemarchand Journal of Physical Chemistry B, 111 (8), p. 2045–2051, 2007. @article{Berthoumieux:2007, title = {Temporal modulation of a spatially periodic potential for kinetically governed oriented motion}, author = {H Berthoumieux and L Jullien and A Lemarchand}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947412367&doi=10.1021%2fjp0669714&partnerID=40&md5=7fe1c3e7a7d426370505fe7f621596d3}, doi = {10.1021/jp0669714}, year = {2007}, date = {2007-01-01}, journal = {Journal of Physical Chemistry B}, volume = {111}, number = {8}, pages = {2045--2051}, abstract = {This theoretical paper introduces an experimental protocol derived from the concept of Brownian motors in order to selectively confer an oriented motion to given charged reactants. Instead of maintaining permanently the system in nonequilibrium conditions, we propose a simple experimental trick to restore periodically a transient out-of-equilibrium regime: the reactive medium is alternately submitted to a sawtooth potential and to a potential ramp. The model provides approximate analytical expressions for the operating conditions allowing us to design the extraction from a mixture of any desired reactant characterized by its rate constants. The orders of magnitude suggest a possible implementation in microsystems where the present approach could be used for separation and analysis. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This theoretical paper introduces an experimental protocol derived from the concept of Brownian motors in order to selectively confer an oriented motion to given charged reactants. Instead of maintaining permanently the system in nonequilibrium conditions, we propose a simple experimental trick to restore periodically a transient out-of-equilibrium regime: the reactive medium is alternately submitted to a sawtooth potential and to a potential ramp. The model provides approximate analytical expressions for the operating conditions allowing us to design the extraction from a mixture of any desired reactant characterized by its rate constants. The orders of magnitude suggest a possible implementation in microsystems where the present approach could be used for separation and analysis. © 2007 American Chemical Society. |
The Nature and Efficiency of Neurotransmitter Exocytosis Also Depend on Physicochemical Parameters Article de journal Christian Amatore; Stephane Arbault; Manon Guille; Frederic Lemaitre Chemphyschem, 8 (11), p. 1597-1605, 2007, ISSN: 1439-4235. @article{RN21b, title = {The Nature and Efficiency of Neurotransmitter Exocytosis Also Depend on Physicochemical Parameters}, author = {Christian Amatore and Stephane Arbault and Manon Guille and Frederic Lemaitre}, doi = {10.1002/cphc.200700225}, issn = {1439-4235}, year = {2007}, date = {2007-01-01}, journal = {Chemphyschem}, volume = {8}, number = {11}, pages = {1597-1605}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Thermal characterization of a microfluidic cell using the 3ωmethod Inproceedings T Barilero; P -O Chapuis; D Pujade; S Guilet; V Croquette; L Jullien; S Volz; C Gosse TRANSDUCERS and EUROSENSORS '07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems, p. 1849–1852, 2007. @inproceedings{Barilero:2007, title = {Thermal characterization of a microfluidic cell using the 3ωmethod}, author = {T Barilero and P -O Chapuis and D Pujade and S Guilet and V Croquette and L Jullien and S Volz and C Gosse}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50049116299&doi=10.1109%2fSENSOR.2007.4300516&partnerID=40&md5=79f1cc20e9e80b3a75700b59074ba356}, doi = {10.1109/SENSOR.2007.4300516}, year = {2007}, date = {2007-01-01}, booktitle = {TRANSDUCERS and EUROSENSORS '07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems}, pages = {1849--1852}, abstract = {Resistive heaters, 36 μm to 2 mm side, were microfabricated in indium-tin-oxide (ITO) using ion beam etching (IBE). A microfluidic cell was subsequently assembled and its thermal behavior was studied by the 3ω method. Experiments and finite element model (FEM) simulations both satisfactorily agreed with a simple one-dimensional model for heat diffusion. ©2007 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Resistive heaters, 36 μm to 2 mm side, were microfabricated in indium-tin-oxide (ITO) using ion beam etching (IBE). A microfluidic cell was subsequently assembled and its thermal behavior was studied by the 3ω method. Experiments and finite element model (FEM) simulations both satisfactorily agreed with a simple one-dimensional model for heat diffusion. ©2007 IEEE. |