Ribulose bisphosphate carboxylase (Ribulose 1,5-bisphosphate carboxylase) catalyses the carboxylation (CO2 addition) or oxygenation (O2 addition) of d-ribulose-1,5-bisphosphate (RuBP) and the subsequent carbon–carbon cleavage to form two molecules of 3-phospho-d-glycerate (PGA) (with CO2) or one molecule of PGA and one molecule of 2-phospho-glycolate (PG; with O2) [1].