Inhibition of ribulose-1,5-bisphosphate carboxylase-oxygenase activities by hydroxylamine

Hydroxylamine directly and reversibly inhibits both activities of homogeneous ribulose-1,5-bisphosphate carboxylase-oxygenase (3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39) isolated from diverse sources. NH2OH is an uncompetitive inhibitor of carboxylase activity with respect to ribulose-bisphosph ate. This reagent also reacts non-enzymically with ribulosebisphosphate to deplete this substrate. Contrary to previous reports, these results indicate that hydroxylamine directly and indirectly inhibits both activities of this bifunctional enzyme.