17. (9 pts) You are studying competitive inhibitors of chymotrypsin. Below are t

Question

17. (9 pts) You are studying competitive inhibitors of chymotrypsin. Below are two you are using. a. Circle the inhibitor you expect to be better, and explain your H3C choice in 1 sentence or less. C-N-CH C-O-CH2CH3 CH H2C CH3 b. What effects should these inhibitors have on the apparent Vmax and Km? H3C C-N CH C-O CH2CH3 max, app CH2 KM, app c. You want to design a transition-state analog for chymotrypsin. Describe one key structural characteristic you would give the analog OH d. Should you expect your transition-state analog in (c) to be a better inhibitor than the molecules shown? Yes No (circle)

Explanation / Answer

Ans. Chymotrypsin hydrolyzes the target peptide bond at its C-ter of the residues with aromatic or bulky hydrophobic side chains like tryptophan, tyrosine, and phenylalanine.

#a. The structure at bottom with aromatic ring is expected to act as a better competitive inhibitor because its structure is similar to the side chain of normal substrate.

#b. Vmax, app = Unaffected, i.e. Vmax,app = Vmax

Km,app = Km,app is higher than Km, i.e. Km,app > Km

A competitive inhibitor does not affect the Vmax.

However, apparent Km is increased in presence of inhibitor.

#c. The transition-state analog for chymotrypsin shall preferably have an aromatic benzene ring, a structure similar to the side chain of normal substrate.

#d. YES

The transition-state analog fits better in the active site/binding pocket of the enzyme when compared to the whole molecule (with aromatic ring) shown. Due to better binding at the active site, the transition-state analog proves to be a better inhibitor.

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