Question

Describe briefly, the charge relay system that operates in chymotrypsin enzyme.

Hint:

Chymotrypsin's charge relay system uses Ser-His-Asp triad to activate serine for peptide bond cleavage.

Answer 1

In chymotrypsin, the charge relay system facilitates the activation of the serine residue for nucleophilic attack on peptide bonds during protein digestion. This system comprises a catalytic triad of Serine (Ser), Histidine (His), and Aspartate (Asp). The process unfolds as follows:

• Aspartate establishes a hydrogen bond with Histidine, thereby stabilizing its positive charge.
• Histidine functions as a base, accepting a proton from the hydroxyl group of Serine.
• This proton abstraction renders Serine a highly reactive nucleophile.
• The activated serine then targets the carbonyl carbon of the peptide bond, resulting in its cleavage.

Consequently, this charge transfer among Asp, His, and Ser significantly boosts the enzyme's catalytic efficiency by priming the serine residue for proteolysis.