Models describing the kinetics of ribulose biphosphate carboxylase-oxygenase.

Abstract Equations are developed to describe the reactions of ribulose 1,5-biphosphate carboxylase—oxygenase with ribulose biphosphate (RuP 2 ), carbon dioxide, and oxygen. It is predicted that at the high concentrations of enzyme sites found in vivo there will be a large proportion of the total RuP 2 bound to the enzyme. The kinetic characteristics of the in vivo reactions with RuP 2 are predicted to be analogous to those which would occur in the presence of a tight-binding substrate. Equations are developed which are applicable when the enzyme is only partially activated by CO 2 and Mg 2+ . The response of carboxylase velocity to CO 2 concentration is sigmoidal when Mg 2+ concentration is low.

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