Spectral evidence for a component involved in hydrogen metabolism of soybean nodule bacteroids.

A component with a difference spectrum similar to that of b-type cytochromes which becomes reduced upon the addition of H(2) has been demonstrated in soybean nodule bacteroids. This electron carrier, referred to as component 559-H(2), is present in hydrogenase-positive strains of Rhizobium japonicum but has not been detected in mutants that lack hydrogenase activity or in hydrogenase-negative wild-type strains. A positive correlation between concentrations of component 559-H(2) and hydrogenase activities has been established. These results provide further evidence that component 559-H(2) is involved in H(2) metabolism in R. japonicum.