Structural variability of the active site of Fe-only hydrogenase and its hydrogenated forms

Abstract

Density functional calculations show that the (cys-S)- (CO)(CN)FeS₂(µ-CO)Fe(CO)(CN) active site of the Fe-only hydrogenase from Clostridium pasteurianum is redox ambivalent and stereochemically flexible at the CO and S bridges, and at the Fe atoms, and with bound hydrogen: the fundamentals of probable mechanisms are revealed.