Chapter 26, Problem 40P

Interpretation Introduction

Interpretation:

The primary structure of somatostatin is to be deduced on the basis of the given information.

Concept Introduction:

Hydrolysis of peptide bonds with the help of enzymes is selective.

Trypsin is a digestive enzyme which catalyzes the hydrolysis of peptide bonds that involve the carboxyl group of arginine or lysine residue.

Chymotrypsin catalyzes the hydrolysis of peptide bonds which involves the carboxyl group of amino acids having an aromatic side chain.

There are three such amino acids – phenylalanine, tyrosine, and tryptophan.

Cysteine has a $-C{H}_{2}SH$ side chain. Upon oxidation, the side chain of the two cysteines is converted to disulfide bridge $-C{H}_{2}S-SC{H}_2-$.

In the Edman degradation, only the N-terminal amide bond is cleaved. It is isolated as a PTH derivative. This helps to determine the sequence of amino acids by each successive degradation.