Chemical Cleavage of Proteins at Asparaginyl-Glycyl Peptide Bonds
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Reaction with hydroxylamine has been used to cleave DNA and to deacylate proteins (at neutral pH—see Note 8). At alkaline pH, however, hydroxylamine may be used to cleave the asparaginyl-glycyl bond. This cleavage tends to generate large peptides, since this pairing of relatively common residues is relatively uncommon, representing about 0.25% of amino acid pairs, according to Bornstein and Balian (1). Apart from generation of peptides for sequencing purposes (e.g., ref. 2), cleavage of Asn-Gly bonds by hydroxylamine has been used to generate peptides for use in mapping ligand binding sites (e.g., ref. 3) and phosphorylation sites (e.g., ref. 4). The method has also been used to cleave a fusion protein at the point of fusion of the constituent polypeptides, although it was noted that formation of hydroxamates may occur (5), as may minor cleavage reactions (3).
KeywordsLarge Peptide Amino Acid Pair Lithium Hydroxide Cysteinyl Residue Reduce Disulfide Bond
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