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  Ilina, Y.; Lorent, C.; Katz, S.; Jeoung, J.H.; Shima, S.; Horch, M.; Zebger, I.; Dobbek, H.: X-ray Crystallography and Vibrational Spectroscopy Reveal the Key Determinants of Biocatalytic Dihydrogen Cycling by [NiFe] Hydrogenases. Angewandte Chemie - International Edition 58 (2019), p. 18710-18714

10.1002/anie.201908258
Open Access Version (externer Anbieter)

Abstract:
[NiFe] hydrogenases are complex model enzymes for the reversible cleavage of dihydrogen (H2). However, structural determinants of efficient H2 binding to their [NiFe] active site are not properly understood. Here, we present crystallographic and vibrational-spectroscopic insights into the unexplored structure of the H2-binding [NiFe] intermediate. Using an F420-reducing [NiFe]-hydrogenase from Methanosarcina barkeri as a model enzyme, we show that the protein backbone provides a strained chelating scaffold that tunes the [NiFe] active site for efficient H2 binding and conversion. The protein matrix also directs H2 diffusion to the [NiFe] site via two gas channels and allows the distribution of electrons between functional protomers through a subunit-bridging FeS cluster. Our findings emphasize the relevance of an atypical Ni coordination, thereby providing a blueprint for the design of bio-inspired H2-conversion catalysts.