Non-enzymatic Proteolysis
Chemicals may be used in laboratory to target specific residue and cleave its peptide bond so that protein may be broken down into smaller polypeptides for analysis. Cyanogen bromide is often used to cleave the peptide bond after a methionine. Other methods may be used to specifically cleave tryptophanyl, aspartyl, cysteinyl, and asparaginyl peptide bonds. Acids such as trifluoroacetic acid and formic acid may also be used.
Strong mineral acids can readily hydrolyse the peptide bonds in a protein. However, some proteins are remarkably resistant to hydrolysis. One well-known example is ribonuclease A, and one method for its purification involves treatment of crude extracts with hot sulphuric acid so that other proteins become degraded while ribonuclease A is left intact.
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