TCB Publications - Abstract

Jordi Cohen, Kwiseon Kim, Matthew Posewitz, Maria L. Ghirardi, Klaus Schulten, Michael Seibert, and Paul King. Molecular dynamics and experimental investigation of H2 and O2 diffusion in [Fe]-hydrogenase. Biochemical Society Transactions, 33:80-82, 2005. (PMC: 2587414)

COHE2005 The [Fe]-hydrogenase enzymes are highly efficient H$_2$ catalysts found in ecologically, and phylogenetically diverse microorganisms, including the photosynthetic green alga, Chlamydomonas reinhardtii. Although these enzymes can occur in several forms, H$_2$ catalysis takes place at a unique [FeS] prosthetic group, or H-cluster, located at the active site. Significant to the function of hydrogenases is how the surrounding protein structure facilitates substrate-product transfer, and protects the active site H-cluster from inactivation. To elucidate the role of protein structure in O$_2$ inactivation of [Fe]-hydrogenases, experimental and theoretical investigations have been performed. Molecular dynamics was used to comparatively investigate O$_2$ and H$_2$ diffusion in CpI ([Fe]-hydrogenase from Clostridium pasteurianum). Our preliminary results suggest that H$_2$ diffuses more easily and freely than O$_2$, which is restricted to a small number of allowed pathways to and from the active site. These O$_2$ pathways are located in the conserved active site domain, shown experimentally to have an essential role in active site protection.

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