Kinetic parameters from progress curves of competing substrates. Application to beta-lactamases

The use of two substrates, one of them a reporter substrate, is often convenient. The time course of an enzymic reaction with competing substrates is given explicitly in the present paper. Kinetic parameters can be readily obtained. The method is applied to the hydrolysis of benzylpenicillin, with cephalosporin C as the reporter substrate, catalysed by a Pseudomonas beta-lactamase.