Mechanism of cellobiose inhibition in cellulose hydrolysis by cellobiohydrolase.
An experimental study of cellobiose inhibition in cellulose hydrolysis by synergism of cellobiohydrolyse I and endoglucanase I is presented. Cellobiose is the structural unit of cellulose molecules and also the main product in enzymatic hydrolysis of cellulose. It has been identified that cellobiose can strongly inhibit hydrolysis reaction of cellulase, whereas it has no effect on the adsorption of cellulase on cellulose surface. The experimental data of FT-IR spectra, fluorescence spectrum and circular dichroism suggested that cellobiose can be combined with tryptophan residue located near the active site of cellobiohydrolase and then form steric hindrance, which prevents cellulose molecule chains from diffusing into active site of cellulase. In addition, the molecular conformation of cellobiohydrolase changes after cellobiose binding, which also causes most of the non-productive adsorption. Under these conditions, microfibrils cannot be separated from cellulose chains, thus further hydrolysis of cellulose can hardly proceed.
Yue
Zhao
Z
State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China.
Bin
Wu
W
Baixu
Yan
Y
Peiji
Gao
G
D002236:Carbohydrate Conformation; D002475:Cellobiose / Q000494:pharmacology*; D002480:Cellulase / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism*; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D002942:Circular Dichroism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006868:Hydrolysis; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014242:Trichoderma / Q000737:chemistry / Q000201:enzymology
D004791:Enzyme Inhibitors; D002475:Cellobiose; D002482:Cellulose; C056374:endoglucanase 1; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase