Adsorption kinetics of cellulase complex and synergistic action between cellulase components

Abstract

The adsorption characteristics of cellulase components was investigated and a mathematical model describing the adsorption process of cellulase complex was proposed, and attempts were made to elucidate the mode of action of cellulase components and to verify the synergistic effect of cellulase components. The adsorption of cellulase enzyme on cellulose adsorbent represented well real behaviors of cellulase components and gave a clue to the understanding of the synergism of cellulase complex. The adsorption process was affected by reaction conditions-the degree of water swelling, agitation speed, the temperature, etc- and adsorbent characteristics. The mathematical model proposed, based on film-surface diffusion theory, agreed well with experimental results. It was found that intraparticle mass transfer resistance dominated the adsorption process of cellulase complex. Endoglucanase consisted of adsorbable and not adsorbable components on solid cellulose adsorbent. Cellobiohydrolase had strongest adsorption affinity. Each cellulase component had separately distinct adsorption site on cellulose chain, which coincided with active site in hydrolysis reaction. Nevertheless, the competitive adsorption between cellulase components was observed in the adsorption process. The degree of competitive adsorption was most outstanding when the composition of cellulase components was nearly same at that in crude cellulase complex. The synergism between cellobiohydrolase and endoglucanase could be elucidated more clearly by this competitive adsorption model.