Chapter 25.5, Problem 31PTS

Interpretation Introduction

Interpretation:

The sequence of 22 amino acid residues in starting peptide need to be identified from trypsin and chymotrypsin fragments.

Concept introduction:

Enzymatic cleavage is a useful method for identifying the sequence of amino acid residue in a large peptide.  This method uses enzymes for hydrolysis of the peptide bonds.  These enzymes are known as peptidases.  Some of the frequently used enzyme are trypsin and chymotrypsin.

Trypsin selectively hydrolyzes the peptide bond at the carboxyl side of arginine and lysine.

Chymotrypsin selectively hydrolyzes the peptide bond at the carboxyl end of amino acids containing aromatic side chains.  The amino acids which have aromatic side chains are phenylalanine, tyrosine and tryptophan.

To identify: the sequence of 22 amino acid residue in the starting peptide.