Characterization of the active site of catalytically inactive forms of [NiFe] hydrogenases by density functional theory.
The inactive forms, unready (Ni-A, Ni-SU) and ready (Ni-B), of NiFe hydrogenases are modeled by examining the possibility of hydroxo, oxo, hydroperoxo, peroxo, and sulfenate groups in active-site models and comparing predicted IR frequencies and g tensors with those of the enzyme. The best models for Ni-A and Ni-SU have hydroxo (mu-OH) bridges between Fe and Ni and a terminal sulfenate [Ni-S(=O)Cys] group, although a hydroperoxo model for Ni-A is also quite viable, whereas the best model for Ni-B has only a mu-OH bridge. In addition, a mechanism for the activation of unready hydrogenase is proposed on the basis of the relative stabilities of sulfenate models versus peroxide models.
Pardo
Alejandro
A
Instituto de Catalisis, Consejo Superior de Investigaciones Cientificas, c/ Marie Curie, 2 Campus Cantoblanco, 28049 Madrid, Spain.
De Lacey
Antonio L
AL
Fernández
Víctor M
VM
Fan
Yubo
Y
Hall
Michael B
MB
D001665:Binding Sites; D004789:Enzyme Activation; D006864:Hydrogenase / Q000737:chemistry*; D008958:Models, Molecular; D013057:Spectrum Analysis
C043296:nickel-iron hydrogenase; D006864:Hydrogenase