[Effect of composition of multienzyme cellulase complexes on rate-limiting steps for non-soluble (native) cellulose hydrolysis]

Abstract

It was shown that the kinetics of multienzyme cellulase complexes are generally characterized by the absence of any single rate-limiting step of hydrolysis, even when the rates of individual steps of the process are substantially different. This peculiarity of the kinetic behaviour of cellulases can be explained in terms of certain "shunt ways" in a series of individual steps of enzymatic degradation of cellulose into glucose. A basic kinetic scheme for the degradation of cellulose was developed and proved experimentally for hydrolysis of milled cotton linters under the action of ten various cellulase complexes from the fungi Trichoderma, Geotrichum and Aspergillus. It was found that the value of the stationary rate of glucose formation in all cases is determined by the effect of two or three cellulolytic components of the complexes. It was concluded that the mechanism of native cellulose hydrolysis is the same for all cellulase complexes under study irrespective of their composition and origin.