Chemical cleavage of proteins

There is a variety of chemical reactions known to result in the cleavage of the peptide bond. Some are nonspecific-for instance, 6M hydrochloric acid at 110°C for 24 h hydrolyzes a polypeptide to a mixture of single amino acids. Others show some discrimination, however, as to the precise nature of the amino acid residues around the bond to be broken. Some of these methods are sufficiently specific to be of use, for instance, for generating peptides for primary structure determination. These methods usefully augment those that use proteolytic enzymes (see Chapter 5 ), especially since they tend to act at positions occupied by less common amino acids and so generate large peptides.