Bradykinin is a nonapeptide, Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg. In addition to one mole of Arg, the following peptides are present after hydrolysis of bradykinin with chymotrypsin,
Arg-Pro-Pro-Gly-Phe-Ser and Pro-Phe

Question

Quizplus · Accepted Answer

Chymotrypsin preferentially cleaves peptide bonds where the carboxyl side is a large hydrophobic amino acid (e.g., phenylalanine, tryptophan, tyrosine). Given the sequence of bradykinin, Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg, chymotrypsin would cleave after the phenylalanine residues, resulting in peptides Arg-Pro-Pro-Gly-Phe and Ser-Pro-Phe-Arg, not the ones listed.

Bradykinin Is a Nonapeptide, Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg