An investigation of ribulosebisphosphate carboxylase activity by high resolution 1 H NMR

The reactions catalysed by ribulosebisphosphate carboxylase/oxygenase have been studied by high resolution proton NMR spectroscopy. The protons of the substrate ribulose‐P 2 and the products of the carboxylase and oxygenase reactions are readily assigned to the various carbon centres. Half of the 3‐phosphoglycerate molecules generated during carboxylase turnover of ribulose‐P 2 in saturating CO 2 concentrations acquire deuterium from the solution at the C 2 position, whereas the other 3‐phosphoglycerate molecules and also the 3‐phosphoglycerate produced as a result of the oxygenase activity contain no deuterium of this type. However, the addition of activated enzyme (i.e., in the presence of an effector) to a solution of ribulose‐P 2 in the near absence of either CO 2 or O 2 catalyses the exchange of the C 3 proton with the deuterium of the solution.