Chapter 9, Problem 17P

Interpretation Introduction

(a)

Interpretation:

The mechanism for peptide bond cleavage by a cysteine protease should be completed.

Concept introduction:

In peptide bond hydrolysis, the strategy of the protease is to generate a nucleophile that attacks the peptide carbonyl group. In cysteine protease, a cysteine residue is activated by a histidine residue and this activated cysteine act as the nucleophile that attacks the peptide bond.

Interpretation Introduction

(b)

Interpretation:

The mechanism for peptide bond cleavage by an aspartyl protease should be completed.

Concept introduction:

In aspartyl protease active site there are two aspartic residues which allow a water molecule to attack the peptide bond. One aspartic acid residue activates the water molecule, polarizes the peptide carbonyl group so that it is susceptible to attack.

Interpretation Introduction

(c)

Interpretation:

The mechanism for peptide bond cleavage by metalloproteases should be completed.

Concept introduction:

The active site of the metalloprotease is composed of a bound metal ion. This metal ion activates a water molecule in order to perform a nucleophilic attack on peptide carbonyl carbon.