ON THE MECHANISM OF HYDROGENASE ACTION

Abstract

Isotope exchange reaction between heavy water and molecular H was measured in a number of different microbial hydrogenase preparations and was compared with their ability (a) to reduce methylene blue with H2 and (b) to produce H2 from reduced methyl viologen. Certain preparations showing hydrogenase activity only by methylene blue reduction fail to catalyze the exchange reaction at an appreciable rate. Special importance is attributed to the correlation between absence of exchange activity and inability to evolve H from reduced methyl viologen. Additional evidence implicating iron as an essential component of hydrogenase is cited, and a generalized formulation of the mechanism of action of the enzyme is presented.