Chapter 19.11, Problem 19.17Q

(a)

Interpretation Introduction

Interpretation:

The structural formula of the peptide $\text{ala-phe-ala}$ and bond of peptide $\text{ala-phe-ala}$ that would be cleaved by chymotrypsin has to be determined.

Concept Introduction:

Certain enzymes called proteolytic enzymes are involved in cleavage of the peptide bonds that are found in the primary structure of polypeptides.

These proteolytic enzymes are often refereed as serine proteases because of the presence of nucleophilic serine at the active site of the enzyme. The proteolytic enzymes are classified on the basis of the specificity of enzyme. For example, the trypsin proteases cleave specifically at the carbonyl end of positively charged amino acids such as arginine or lysine except for the cases of amino acid that are followed by amino acid proline.

Chymotrypsin cleaves at the carbonyl terminal of aromatic amino acids such as phenylalanine, tyrosine, and tryptophan.

Elastase cleaves at the C-terminus of valine, serine, alanine, leucine, glycine, or isoleucine.

(b)

Interpretation Introduction

Interpretation:

The structural formula of the peptide $\text{tyr-ala-tyr}$ and bond of peptide $\text{tyr-ala-tyr}$ that would be cleaved by chymotrypsin has to be determined.

Concept Introduction:

Refer to part (a).