A facile method to determine the CO2/O 2 specificity factor for ribulose bisphosphate carboxylase/oxygenase

A rapid method to determine the CO2/O2 specificity factor of ribulose 1,5-bisphosphate carboxylase/oxygenase is presented. The assay measures the amount of CO2 and O2 fixation at varying CO2/O2 ratios to determine the relative rates of each reaction. CO2 fixation is measured by the incorporation of the moles of(14)CO2 into 3-phosphoglycerate, while O2 fixation is determined by subtraction of the moles of CO2 fixed from the moles of RuBP consumed in each reaction. By analyzing the inorganic phosphate specifically hydrolyzed from RuBP under alkaline conditions, the amount of RuBP present before and after catalysis by rubisco can be determined.