Vendredi 7 février 2020 à 14h (salle Magat)
"Surface enhanced vibrational spectroscopies and bioelectrochemistry : developing tools to understand the reaction mechanism of membrane proteins"
Résumé
The molecular details of energy supply mechanisms, which are central to life, are in the focus of our research. Experiments have been developed, which reveal how protons, other ions and water molecules are drawn through membrane proteins, how the synthesis of small molecules is catalyzed and how these processes are coupled to electron transfer reactions or to conformational movements. We focus on the structural, dynamic and energetic requirements of individual amino acids and the cofactor sites that rule them.
Vibrational spectroscopy provides molecular fingerprints of a proteins catalytic reaction. By combining infrared spectroscopies and solid-state plasmonic nanostructures with reaction-induced approaches, the observation of a proteins action is possible at the level of single functional groups within large proteins. This provides information essential for understanding an enzymatic mechanism. Different examples, including proton translocation in transport proteins (1, 2) and in enzymes of the respiratory chain (3, 4), will be given together with a perspective on the applications for the far infrared (Thz) spectral range (5).
The use of the same nanostructures surfaces for the study of the electrocatalytic properties of these membrane proteins is possible. The oxygen reactivity of enzymes from different bac terial enzymes is presented (4, 6).
1. Grytsyk, N., Sugihara, J., Kaback, HR., Hellwig, P. pKa of Glu325 in LacY. (2017) Proc Natl Acad Sci U S A. 114(7):1530-1535.
2. Grytsyk, N., Seica Santos, AF., Sugihara, J., Kaback, HR., Hellwig, P. Arg302 governs the pK of Glu325 in Lac Y (2019) Proc Natl Acad Sci U S A. 116 (11) 4934-4939
3. Kriegel, S., Uchida, T., Osawa, M., Friedrich, T., Hellwig, P. ‘Biomimetic environment to study E. coli complex I through Surface-Enhanced IR Absorption Spectroscopy’ (2014) Biochemistry 53(40):6340-7.
4. Meyer, T., Melin, F., Xie, H., von der Hocht, I., Choi, SK., Noor, MR., Michel, H., Gennis, RB., Soulimane, T., Hellwig, P. ‘Evidence for distinct electron transfer processes in terminal oxidases from different origin by means of protein film voltammetry’ (2014) J Am Chem Soc. 136(31):10854-7.
5. El Khoury, Y., Hellwig P. Far infrared spectroscopy of hydrogen bonding collective motions in complex molecular systems. (2017) Chem Commun (Camb). 53(60):8389-8399.
6. Safarian, S., Hahn, A., Mills, DJ., Radloff, M., Eisinger, ML., Nikolaev, A., Meier-Credo, J., Melin, F., Miyoshi, H., Gennis, RB., Sakamoto, J., Langer, JD., Hellwig, P., Kühlbrandt, W., Michel, H., Active site rearrangement and structural divergence in prokaryotic respiratory oxidases (2019) Science 366(6461):100-104.
