The role of diffusion in enzyme kinetics.

A discussion is given of the general role of diffusion in enzyme kinetics based upon a rigorous theory for bimolecular association and dissociation steps that was presented previously, and criteria are formulated for the dependence of the over-all rate on medium viscosity. With these criteria it is possible to conclude that a number of enzymes will exhibit no appreciable dependence of over-all rate on the medium viscosity, quite irrespective of the as yet unmeasured rate constants for association and dissociation of enzyme and substrate. The effect of adsorbing the enzyme onto the surface of a much larger spherical colloidal particle is considered with the conclusion that the rate will either remain the same or decrease, and that its sensitivity to medium viscosity will remain the same or increase.