Mixed enzymic reaction--internal diffusion kinetics of nonuniformly distributed immobilized enzymes. The system...

Two types of (CNBr-activated) Agarose-staphylococcal endonuclease derivatives have been prepared, one with the enzyme uniformly distributed in the support, and the other with the enzyme preferentially bound in the most external part of the support particles; the latter were obtained using agarose of very small pores and a high degree of activation. Quantitative enzyme distribution has been determined by scanning fluorescence microscopy. With these insoluble enzyme derivatives, a kinetic study for the hydrolysis of a mononucleotide has been carried out. A simple theoretical model for nonuniformly distributed insoluble enzyme derivatives, which considers only the case of mixed enzymic reaction-internal diffusion kinetics, is proposed. The experimental data agree very well with the predictions of the model.