Different kinetic patterns in the alpha-chymotrypsin-catalysed hydrolysis of synthetic ester substrates.
The reaction of alpha-chymotrypsin with AcTyr-OEt and with AcTrp-OEt at pH 7.0 and 7.8 was studied over a wide range of substrate concentrations. The reaction with AcTyr-OEt at pH 7.8 was shown to be non-hyperbolic using a variety of criteria whereas those at pH 7.0 with the same substrate and at both pH values with AcTrp-OEt were hyperbolic. The non-hyperbolicity of the reaction with AcTyr-OEt at pH 7.8 followed a pattern of negative cooperativity with a Hill coefficient for the high substrate concentration range of 0.48. Although other explanations are possible, the pH dependence of the reaction with AcTyr-OEt could be related to the slow transition of the two known forms of the enzyme.
D002264:Carboxylic Acids / Q000378:metabolism*; D002384:Catalysis; D002918:Chymotrypsin / Q000378:metabolism*; D004952:Esters / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D013379:Substrate Specificity
D002264:Carboxylic Acids; D004952:Esters; D002918:Chymotrypsin