(b) The values of kinetic parameters for a variety of synthetic ester and peptide substrates ofa-chymotrypsin are compared for the reaction scheme below where ES is the Michaelis complex, ES'E+SSubstrateK₁N-Ac-Trp–OC₂H5N-Ac-Phe-OC2H5N-Ac-Leu-OC2H5N-Ac-Phe-CONH2N-Ac-Tyr-p-nitro-anilideESK₂3.513.03.21.7K-₁is the acylenzyme, P₁ is the first product to be released, P2 is the second product, k2 is the acylationrate constant, k3 is the deacylation rate constant, and kcat = k2 k3/( k2 + k³). In the table below, N-Ac = N-acetyl; -CONH₂ = carboxamide; -OC₂H5 = ethyl ester; p-nitroanilide = −NH-C6H4-NO2simulating a peptide group.ES'K2 (S-¹) K3 (S-1)0.842.20.19P₁K30.073H→ E+ P2Kcat (S-1)0.821.90.180.0700.038KM (MM)0.081.34.224.00.351Kcat/ KM (mM-¹ s¯¹)10.31.50.040.0030.11The value of kcat for N-Ac-Phe-OC2H5 is two-fold greater than that for the L-tryptophanyl analog andmore than 10-fold greater than the value of kcat for the ester substrate N-Ac-Leu-OC2H5. Does thismean that N-Ac-Phe-OC2H5 exhibits greater specificity as a substrate than the other ester sub-strates? On what basis do you base your conclusion? Also, which kinetic parameters help to distin-guish between specificity (of substrate recognition) and affinity o0f a substrate when comparing a se-ries of substrates of an enzyme?

Chymotrypsin catalyzed peptide bond hydrolysis takes place in 2 phases after the enzyme binds the…

Answered: The value of kcat for N-Ac-Phe-OC₂H5 is…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter26: Synthesis And Degradation Of Nucleotides

Section: Chapter Questions

Problem 17P

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Similar questions

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the following peptide is incubated as chymotrypsin: Gly-Val-Phe-Lys-Ala. Present the detailed chemical mechanism by which chymotrypsin hydrolyzes this peptide. Briefly explain each step. Include only the structure of the final products of the reaction.
An inhibitor that specifically labels chymotrypsin at histidine 57 is N-tosylamido-l-phenylethyl chloromethylketone. How would you modify the structure of this inhibitor tolabel the active site of trypsin?
An inhibitor that specifically labels chymotrypsin at histidine 57 is Ntosylamido-l-phenylethyl chloromethyl ketone. How would you modify the structure of this inhibitor to label the active site of trypsin?
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