Which of the following located in the active site of the enzyme chymotrypsin participates in acid-base...

Which of the following located in the active site of the enzyme chymotrypsin participates in acid-base chemistry?

The side chain oxygen of serine

The amide group of glycine

The hydrophobic pocket Histidine

The amide group of serine

Expert Solution

Answer :Histidine

Chymotrypsin cleaves the CO of the amide bond.Chymotrypsin enzyme binding to its substrate takes placein two number of steps:

1)Acyl-enzyme intermediate formation by substrate -acylation and then decylation to restore the enzyme.

2)Three amino acids catalyzes this reactions-histidine,aspartate and Serine.Of these three the aspartate Oxygen binds to the N-delta hydrogens of histidine (increasing the pKa of H on its e-H so that it is activated to deprotonate serine. Serine on deprotonation attacks the CO of protein as nucleophile to cleave the CO-NH amide bond

Thus, histidine takes part in the acid -base rxn between the protein and the serine residue in the active site of chymotripsin.

queen_honey_blossom answered 2 years ago

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