Amino Acids, Peptides and Proteins - T. Dévényi, J. Gergely 1976

Hydrolysis of proteins and peptides
Partial acid hydrolysis of proteins and peptides

Principle of the method. If the protein or peptide under study, dissolved in concentrated HCl, is incubated at 37°C for 72–96 h, partial degradation occurs. In the resulting hydrolysate, di- and tripeptides predominate among other Cleavage products, i.e., only a relatively small proportion of peptide bonds are cleaved during Hydrolysis.

Applications. Structural analysis of large Peptides, comparative Analysis of Proteins, and isolation of specific peptides (e.g., acidic, basic, and neutral peptides) from proteins and Polypeptides.

PROCEDURE

The protein or peptide is hydrolyzed in a 100-fold excess of concentrated HCl at 37°C for 3–4 days in sealed, evacuated ampoules. After hydrolysis, the acid is removed as described above.

NOTES

1. All Tryptophan residues are destroyed during hydrolysis.

2. On average, the hydrolysates consist of 25% free Amino Acids, while the remaining peptides are predominantly dipeptides.

3. Partial hydrolysis in dilute rather than concentrated acid can lead to artifacts resulting from transpeptidation reactions.

4. Prior to partial hydrolysis, it is recommended to oxidize the starting material with performic acid for the same reasons mentioned in the section on complete hydrolysis.