Chymotrypsin is a digestive enzyme with a catalytic optimum between pH 7.8 and 8.0. However, due to the presence of gastri juice, chymotrypsin often functions in an environment of pH 5.5-7.0. The imidazole group of free histidine has a pK₂ of 6.0. Use the Henderson-Hasselbalch equation to determine the ratio of deprotonated to protonated His 57 imidazole moieties at pH 5.9. pH = pK₁ + log ( [AA]) [His] [His+] x10 TOOLS Aside from positioning, what do you think is the role of the Asp 102 residue? It allows nucleophilic attack by His 57. It protonates His 57 prior to substrate binding. [His] It decreases the ratio. [His+] ● It raises the pka of His 57.

Chymotrypsin is a digestive enzyme with a catalytic optimum between pH 7.8 and 8.0. However, due to the presence of gastri juice, chymotrypsin often functions in an environment of pH 5.5-7.0. The imidazole group of free histidine has a pK₂ of 6.0. Use the Henderson-Hasselbalch equation to determine the ratio of deprotonated to protonated His 57 imidazole moieties at pH 5.9. pH = pK₁ + log ( [AA]) [His] [His+] x10 TOOLS Aside from positioning, what do you think is the role of the Asp 102 residue? It allows nucleophilic attack by His 57. It protonates His 57 prior to substrate binding. [His] It decreases the ratio. [His+] ● It raises the pka of His 57.

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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