Catalytic Mechanism of the Metal-Free Hydrogenase from Methanogenic Archaea: Reversed Stereospecificity of the Catalytic and Noncatalytic Reaction

Abstract

By activation of the hydrogen acceptor, the metal-free hydrogenase from methanogenic archaea catalyzes the reduction of methenyl tetrahydromethanopterin with H2. According to NMR spectroscopic analysis of the conformation of the hydrogen acceptor in solution and of the stereospecificity of the catalyzed and noncatalyzed reaction, in the enzyme-catalyzed reaction the hydrogenation product is formed in a constraint conformation which relaxes upon dissociation from the enzyme. This exergonic conformational change could help to avoid product inhibition of the enzyme.