The oxygenase activity of ribulose-1,5-bisphosphate carboxylase from Rhodospirillum rubrum

Catalysis by pure ribulose bisphosphate carboxylase from $\text{Rhodospirillum rubrum}$, which is a dimer (MW: 114,000) lacking small subunits, is inhibited by oxygen. Oxygen is a competitive inhibitor with respect to carbon dioxide. In the absence of carbon dioxide, the enzyme catalyzes the oxygenolytic cleavage of ribulose-1,5-bisphosphate with consumption of one mole of oxygen per mole of 3-phosphoglycerate produced.