Friday, 07 October 2022 12:00

In-person event – venue MSG-024/25, Bernal Institute.

Tea/Coffee available in MSSi Social Space from 14h45


Methods for the Study of the Reaction of Membrane Proteins from

Bacterial Respiratory Chains


Although the architectures of several membrane proteins in respiration as well as the basic chemical reactions have been described, the interactions on molecular level, the diversity and efficiency of the reaction mechanisms in bacterial systems, are under debate. Electrochemical and spectroscopic experiments will be presented that have been developed to study coupled electron and proton reactions, identify the contribution of individual amino acids, study the reactivity towards small molecules and, importantly, correlate it with the microenvironment of the cofactors.
Three main projects will be presented:
1. Electrocatalytic studies on different membrane proteins from the respiratory chain, that demonstrate a different reactivity towards the substrate and the adaptation of the bacteria to the respective environment. 1, 2
2. Surface enhanced IR spectroscopies (SEIRAS), that allow studies on the reactivity down to the picomolar level and on protein monolayers. Recent advances in the creation of ideal surfaces for SEIRAS will be given. 3-5
3. Finally, the possibility to tailor nanostructure to enhance individual infrared signals will be demonstrated and the perspectives of these techniques for other fields of chemistry and biology will be discussed.6

Recent references
1. 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.
2. Nikolaev, A., Safarian, S., Thesseling, A., Wohlwend, D., Friedrich, T., Michel, H., Kusumoto, T., Sakamoto, J., Melin, F.,
Hellwig P. (2021) Biochim Biophys Acta Bioenerg. 1862 148436.
3. Grytsyk, N., Santos Seiça, A.F., Sugihara, J., Kaback, H.R., Hellwig, P. ‘Arg302 governs the pKa of Glu325 in LacY’ (2019) Proc.
Natl. Acad. Sci. U.S.A. 116, 4934-4939.
4. Santos Seiça, A.F., Iqbal, M.H., Carvalho, A., Choe, J-Y., Boulmedais, F. and Hellwig, P. Study of Membrane Protein
Monolayers Using Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS): Critical Dependence of Nanostructured
Gold Surface Morphology (2021) ACS Sensors,
5. Santos Seica, A.F., Schimpf, J., Friedrich, T., Hellwig, P. Visualizing the movement of the amphipathic helix in the respiratory
complex I using a nitrile infrared probe and SEIRAS. (2020) FEBS Lett. 594(3):491-496.
6. Omeis, F., Santos Seica, A.F., Bernard, R., Javahiraly, N., Majjad, H., Moss, D., Hellwig, P., Following the Chemical
Immobilization of Membrane Proteins on Plasmonic Nanoantennas Using Infrared Spectroscopy (2020) ACS Sensors, 5 (7),


Petra Hellwig is full professor in the Faculty of Chemistry of the University of Strasbourg and directs the research unit Chemistry of Complex Matter, the PhD School of Chemistry of the University, as well as the Laboratory of Bioelectrochemistry and Spectroscopy. With her interdisciplinary expertise in biophysics and physical chemistry, she uses vibrational spectroscopy and bioelectrochemistry for the study of the reaction mechanism of membrane proteins and their principle(s) of operation. Her research focuses on enzymes from the respiratory chain and as membrane transporters

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