Hydrogenases catalyze the reversible heterolytic splitting of H2 at binuclear (NiFe or FeFe) metal centers, carrying unusual CO and CN- ligands (1). To better understand the catalytic cycles the intermediates are trapped and characterized by a combination of electrochemical and spectroscopic methods, using mostly vibrational and magnetic resonance techniques with high local resolution. The obtained parameters are verified by DFT calculations. For the [FeFe]-hydrogenase HydA1 from Chlamydomonas reinhardtii the artificial maturation is described using different - also isotopically labeled - di-iron complexes mimicking the active site (2). This approach enabled various new experiments, e. g. the direct detection of an iron-bound terminal hydride in the reduced state of the enzyme, using nuclear resonance vibrational spectroscopy (NRVS). IR-spectroelectrochemistry at different pH values enabled the detection of further intermediates, leading to a vastly improved understanding of the catalytic mechanism. NMR experiments have been performed on apo-HydA1 and HydA1, illustrating the usefulness of this method to study native and chemically or genetically modified hydrogenases. The artificial maturation and characterization of the highly active [FeFe] hydrogenase from Desulfovibrio desulfuricans is reported (3). The oxygen sensitivity of these enzymes is discussed. It can significantly be improved by embedding the hydrogenase in a tailor-made polymer matrix (4). It is demonstrated that hydrogenases and related model systems can successfully be attached to electrodes and used in devices. (1) Lubitz, W., Ogata, H., Rüdiger, O.; Reijerse, E., Chem. Rev., 114, 4081(2014) (2) Esselborn, J. Lambertz, C., Adamska-Venkatesh, A., Simmons, T., Berggren, G., Noth, J., Siebel, J., Hemschemeier, A., Artero, V., Reijerse, E., Fontecave, M., Lubitz, W., Happe, T., Nat. Chem. Biol. 9, 607 (2013); Siebel, J., Adamksa-Venkatesh, A., Weber, K., Rumpel, S., Reijerse, E. J., Lubitz, W., Biochemistry 54, 1474 (2015) (3) Birrell, J., Wrede, K., Pawlak, K., Rodriguez-Maciá, P., Rüdiger, O., Reijerse, E. J., Lubitz, W., Isr. J. Chem. 56, 852 (2016) (4) Plumeré, N., Rüdiger, O., Oughli, A.A., Williams, R., Vivekananthan, J., Pöller, S., Schuhmann, W. Lubitz, W., Nat. Chem., 2014, 6, 822; Oughli, A.A., Conzuelo, F., Winkler, M., Happe, T., Lubitz, W. Schuhmann, W., Rüdiger, O., Plumeré, O., Angew. Chem., Int. Ed., 2015, 54, 12329.

Insights into the catalytic mechanisms of [FeFe] hydrogenase: Inspiration for the design of molecular catalysts

253rd National Meeting (2017)

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