The Active Species of “CO2” Utilized by Ribulose Diphosphate Carboxylase

Abstract The active species of CO2, i.e. CO2 or HCO3-, utilized in the ribulose diphosphate carboxylase reaction was determined with the use of homogeneous preparations of the spinach enzyme. Employing an assay system predicated upon the observation that the hydration of CO2 requires more than 60 sec to reach equilibrium at temperatures below 15°, data were obtained which are quite compatible with those expected if CO2 is the active species.