Dithiomethylether as a ligand in the hydrogenase h-cluster.
Pandey, A.S., Harris, T.V., Giles, L.J., Peters, J.W., Szilagyi, R.K.(2008) J Am Chem Soc 130: 4533-4540
- PubMed: 18324814 
- DOI: https://doi.org/10.1021/ja711187e
- Primary Citation of Related Structures:  
3C8Y - PubMed Abstract: 
An X-ray crystallographic refinement of the H-cluster of [FeFe]-hydrogenase from Clostridium pasteurianum has been carried out to close-to atomic resolution and is the highest resolution [FeFe]-hydrogenase presented to date. The 1.39 A, anisotropically refined [FeFe]-hydrogenase structure provides a basis for examining the outstanding issue of the composition of the unique nonprotein dithiolate ligand of the H-cluster. In addition to influencing the electronic structure of the H-cluster, the composition of the ligand has mechanistic implications due to the potential of the bridge-head gamma-group participating in proton transfer during catalysis. In this work, sequential density functional theory optimizations of the dithiolate ligand embedded in a 3.5-3.9 A protein environment provide an unbiased approach to examining the most likely composition of the ligand. Structural, conformational, and energetic considerations indicate a preference for dithiomethylether as an H-cluster ligand and strongly disfavor the dithiomethylammonium as a catalytic base for hydrogen production.
Organizational Affiliation: 
Department of Chemistry and Biochemistry and Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, Montana 59717, USA.