ADSORPTION AND SYNERGISM OF CELLOBIOHYDROLASE-I AND CELLOBIOHYDROLASE-II OF TRICHODERMA-REESEI DURING HYDROLYSIS OF MICROCRYSTALLINE CELLULOSE

Hydrolysis of microcrystalline cellulose (Avicel) by cellobiohydrolase I and II (CBH I and II) from Trichoderma reesei has been studied. Ads orption and synergism of the enzymes were investigated. Experiments we re performed at different temperatures and enzyme/substrate ratios usi ng CBH I and CBH II alone and in reconstituted equimolar mixtures. Fas t protein liquid chromatography (FPLC) analysis was found to be an acc urate and reproducible method to follow the enzyme adsorption. A linea r correlation was found between the conversion and the amount of adsor bed enzyme when Avicel was hydrolyzed by increasing amounts of CBH I a nd/or CBH II. CBH I had lower specific activity compared to CBH II alt hough, over a wide concentration range, more CBH I was adsorbed than C BH II. Synergism between the cellobiohydrolases during hydrolysis of t he amorphous fraction of Avicel showed a maximum as a function of tota l enzyme concentration. Synergism measured as a function of bound enzy me showed a continuous increase, which indicates that by decreasing th e distance between the two enzymes the synergism is enhanced. The adso rption process for both enzymes was slow. Depending on the enzyme/subs trate ratio it took 30-90 min to reach 95% of the equilibrium binding. The amount of bound enzyme decreased with increasing temperature. The two enzymes compete for the adsorption sites but also bind to specifi c sites. Stronger competition for adsorption sites was shown by CBH I. (C) 1994 John Wiley & Sons, Inc.