X‐ray Crystallography and Vibrational Spectroscopy Reveal the Key Determinants of Biocatalytic Dihydrogen Cycling by [NiFe] Hydrogenases. (25th October 2019) - Ilina, Yulia
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. Abstract : An einer F420 ‐reduzierenden [NiFe]‐Hydrogenase aus Methanosarcina barkeri wird beispielhaft gezeigt, dass das Proteinrückgrat ein gespanntes chelatbildendes Gerüst darstellt, das das aktive [NiFe]‐Zentrum für effiziente H2 ‐Bindung und ‐Konversion modifiziert. Die Proteinmatrix steuert ebenfalls H2 ‐Diffusion zum [NiFe]‐Zentrum über zwei Gaskanäle und ermöglicht eine Elektronenumverteilung zwischen funktionellen Protomeren über einen verbrückenden FeS‐Cluster.