A mechanistic model for the enzymic degradation of synthetic biopolymers

The degradation pathway of a synthetic biopolymer, poly-N5-(2-hydroxyethyl)-L-glutamine, by papain under physiological conditions, was extensively investigated. The enzymic reaction was found to be rather complex: it progressively slows down, and comes to an end when the degradation fragments are tetrapeptides. In order to account for this phenomenon, a modified Michaelis-Menten kinetic model is proposed, in which Km is assumed to be dependent on the degree of polymerization of the macromolecular substrate, and therefore varies as the degradation reaction proceeds. The new model accurately describes all the experimental data, and allows one to predict the entire course of the reaction. The behaviour of the system considered is interpreted to represent a model of biological recognition at the molecular level.