BIOCHEM 3G03 Lecture Notes - Lecture 6: Enzyme Catalysis, Acetoacetic Acid, Schiff Base
4 Nov 2018
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Increasing the temperature increasing concentrations of reacting substrates adding a catalyst. How to increase rate of a chemical reaction: Chymotrypsin synthesized in pancreas and secreted into small intestine hydrolyzes peptide bonds at rate of 190 per second. 1. 7 x 10^11 times faster than without a catalyst. Catalytic triad of chymotrypsin amino acids in the triad include: aspartic acid histidine serine chymotrypsin known as serine protease scissile bond - bond to be cleaved by hydrolysis - placed near ser 195. His 57 acts as a base catalyst and takes a proton from ser 195 so oxygen can act as covalent catalyst. Asp 102 promotes catalysis by stabilizing the resulting positively charged imidazole group of his 57. His 57 then acts as acid catalyst to donate proton to nitrogen of scissors peptide bond two phases of chymotrypsin-catalyzed peptide bond hydrolysis: nucleophilic attack of ser 195 on substrate"s carbonyl leads to transition state.
