title: Enzymatic kinetic of cellulose hydrolysis: inhibition by ethanol and cellobiose.
abstract: The ethanol effect on the Trichoderma reesei cellulases was studied to quantify and clarify this inhibition type. To determine inhibition parameters of crude cellulase and purified exoglucanase Cel7A, integrated Michaelis-Menten equations were used assuming the presence of two inhibitors: cellobiose as the reaction product and ethanol as a possible bioproduct of cellulose fermentation. It was found that hydrolysis of cellulose by crude enzyme follows a model that considers noncompetitive inhibition by ethanol, whereas Cel7A is very slightly competitively inhibited. Crude cellulase is much more inhibited (K(iul) = K(icl) = 151.9 mM) than exoglucanase Cel7A (K(icl) = 1.6 x 1015 mM). Also, calculated inhibition constants showed that cellobiose inhibition is more potent than ethanol inhibition both for the crude enzyme as well as exoglucanase Cel7A.
authors: CETAV-Departamento de Engenharia Biológica e Ambiental, Universidade de Trás-os-Montes e Alto Douro, Apartado 1013, 5001-911 Vila Real, Portugal. bezerra@utad.pt
authors: Rui M F
authors: RM
authors: Bezerra
authors: Albino A
authors: AA
authors: Dias
mesh_terms: D002475:Cellobiose / Q000737:chemistry*; D002480:Cellulase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques; D003198:Computer Simulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D008956:Models, Chemical; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D004791:Enzyme Inhibitors; D002475:Cellobiose; D000431:Ethanol; D002482:Cellulose; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase