ENZYMES ON IMMOBILIZED SUBSTRATE SURFACES - REACTION

The goal of this paper is to measure the overall reaction rate of irreversibly adsorbed but mobile enzymes on substrate-coated surfaces and to model the interplay between reaction and diffusion in this system. Our model system uses collagenase, an enzyme that degrades native collagen, and synthetic surfaces covered with a peptide that is a substrate for collagenase. We employ a multisurface flow cell device to measure the change of ultraviolet absorbance as collagenase hydrolyzes the surface-bound peptide substrate. The overall reaction rate is enhanced as the surface enzyme concentration is increased. By changing the buffer pH we discern the influence of the intrinsic kinetic rate on the overall reaction rate. Employing surfaces containing fewer bound substrates, we probe the effect of the distance between substrates on the overall reaction rate to show that this process is governed by both reaction and diffusion. Using a modified Smoluchowski theory, we model this interplay to determine the intrinsic reaction rate of the surface process and compare this value to those found for collagenase reaction in solution. (C) 1995 Academic Press, Inc.