Evidence for the involvement of superoxide anions in the oxygenase reaction of ribulose-1,5-diphosphate carboxylase.

The mechanism of oxygenase reaction catalysed by ribulose-1,5-diphosphate carboxylase was investigated using superoxide dismutase from bovine erythrocytes. Inclusion of superoxide dismutase in the assay mixture resulted in strong inhibition of oxygenase reaction. Ribulose-1,5-diphosphate was found to compete for superoxide anions with dismutase and nitroblue tetrazolium which also inhibited the oxygenase reaction. These observations indicate the possible involvement of superoxide anions in the oxygenase reaction.