The use of electron-paramagnetic-resonance spectroscopy to establish the properties of nickel and the iron-sulphur cluster in hydrogenase from Chromatium vinosum.

Hydrogenase [hydrogenase: (acceptor) oxidoreductase, EC 1.12. . -1 is present in many bacteria. It is one of the enzymes having potential use in the biophotolysis of water (Weaver et al.. 1980). When we began our research on hydrogenase in 1977, two types of enzymes were known: (i) enzymes containing 12 Fe atoms and an equivalent amount of acid-labile S atoms and (ii) enzymes containing only four Fe and four acid-labile S atoms (for reviews see Adams et al., 1980; Weaver et al., 1980). Since the 4-Fe enzymes were reported t o be stable in air, in contrast to the 12-Fe enzymes known at that time, we decided to study the 4-Fe enzyme from Chromatium vinosum as being the simplest stable enzyme carrying out the reaction of interest: 2 e + 2 H + + H2.