Damien Laage's Group - Research

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Damien Laage's Group - Research

 

The focus of our group is on constructing theories and performing calculations to understand, at the molecular level, chemical reactions and molecular processes in solution and in biological environments. A special attention is given to the connection of theory and simulation with experimental results, e.g. from ultrafast spectroscopy.

Water hydrogen-bond and reorientation dynamics

The reorientation of a water molecule is important for a host of phenomena, ranging over - in an only partial listing - the key dynamic hydrogen-bond network restructuring of water itself, aqueous solution chemical reaction mechanisms and rates, ion transport in aqueous solution and membranes, protein folding, and enzymatic activity. In the recent years, we have investigated the water reorientation mechanism and found a novel sudden, large-amplitude jump mechanism, which constrasts with the commonly assumed Debye rotational diffusion mechanism, characterized by small-amplitude angular motion. This work has been extended to describe water dynamics next to a broad series of aqueous solutes, with hydrophobic, hydrophilic, and amphiphilic character, ranging from tetramethylurea to halide ions and amino acids. Further applications to proteins and DNA are underway.

  1. Damien Laage and James T. Hynes, "A Molecular Jump Mechanism of Water Reorientation", Science 311, 832-835 (2006); on-line link
  2. Damien Laage and James T. Hynes, "Reorientational Dynamics of Water Molecules in Anionic Hydration Shells", Proc. Natl. Acad. Sci. 104, 11167-11172 (2007); on-line link
  3. Damien Laage, Guillaume Stirnemann, Fabio Sterpone, Rossend Rey and James T. Hynes, "Reorientation and allied dynamics in water and aqueous solutions", Annu. Rev. Phys. Chem. 62, 395-416 (2011); on-line link

Two-dimensional infrared spectroscopy

Two-dimensional infrared (2D-IR) spectroscopy is a modern nonlinear spectroscopy technique which has for example been successfully used to study hydrogen-bond dynamics and protein structural relaxation. However,interpreting the multidimensional spectral patterns is challenging and requires an advanced theoretical framework. Our recent work has focussed on the calculation of 2D-IR spectra of water either in the pure liquid case or in aqueous solutions, in order to provide a molecular interpretation of the experimental spectra.

A novel project in collaboration with Ward H. Thompson (Univ. Kansas, Lawrence) and Thomas Elsaesser (MBI, Berlin) aims at developing new theoretical approaches to calculate 2D-IR spectra in the presence of intermolecular vibrational energy transfer; these will be applied to the understanding of recent pioneering 2D-IR spectra on hydrated biomolecules including DNA, in order to derive a molecular understanding of the heat dissipation mechanism in hydrated DNA.

This project is supported by the French Agence Nationale de la Recherche within a Projet Blanc.

  1. Guillaume Stirnemann, James T. Hynes and Damien Laage, "Water hydrogen-bond dynamics in aqueous solutions of amphiphiles", J. Phys. Chem B 114, 3052-3059 (2010)
  2. Guillaume Stirnemann and Damien Laage, "Direct evidence of angular jumps during water reorientation through 2D IR anisotropy", J. Phys. Chem. Lett. 1, 1511-1515 (2010)

Enzyme catalysis in organic solvents

Enzymes are remarkably efficient catalysts and their recent use in non-aqueous organic solvents is opening up a tremendous range of applications in synthetic chemistry: since, surprisingly, most enzymes do not denature in these non-natural environments, new reactions involving e.g. water-insoluble reagents can be catalyzed, while unwanted degradation side reactions are suppressed.

However, a key challenge for these applications is to overcome the greatly reduced catalytic activity compared to aqueous conditions. Empirically, adding activators such as salts or small amounts of water dramatically enhances the activity, but the underlying mechanisms have remained elusive, thus preventing a rational optimization.

Through analytic modeling and numerical simulations, our goal is to provide an atomic-scale detailed description of enzyme catalysis in organic solvents, including the key role of the environment. This molecular insight will then be used to design rigorous new procedures for the rational engineering of systems with dramatically enhanced activities, both through optimized choices of solvents and additives, and through targeted protein mutations.

This project is supported by the European Research Council within a Starting Grant.