Practical Protein Chemistry - A. Darbre 1989

Enzymatic fragmentation of the polypeptide chain
Proteases with low specificity
Pepsin

Detailed information on the catalytic activity and Applications of Pepsin can be found in [11, 27]. This enzyme is virtually the only extensively studied acidic protease available commercially (along with protease V8 from S. aureus).

3.6.3.1. Specificity and Hydrolysis Conditions.

Specificity. Pepsin is primarily specific to peptide bonds formed by aromatic and bulky aliphatic amino acid residues. Bonds involving glutamic acid are also susceptible to the enzyme's action. Unfortunately, pepsin exhibits a broad specificity toward A number of other peptide bonds, making The ultimate outcome of partial hydrolysis difficult to predict. The enzyme is utilized for the Limited proteolysis of native Proteins. For instance, Treatment with pepsin at pH 4.5–5.0 yields large immunoglobulin fragments [73].

Hydrolysis conditions. Pepsin exhibits activity within the pH range of 1–5 (with optimum conditions at pH 2.0). Hydrolysis is carried out in 10 mM HCl or 5% acetic acid. The enzyme is irreversibly inhibited at pH>6.0. The most successful results are achieved using pepsin for determining the positions of Disulfide Bonds, as disulfide exchange is minimal at low pH; incubation with pepsin yields short Peptides with correctly closed disulfide bonds [101] (see also Section 4.4.2).