Oxidation of Insulin by Performic Acid
Abstract
FROM the determination of the terminal residues of insulin, it was suggested that the submolecule of molecular weight 12,000 is made up of four peptide chains bound together by -S-S- linkages1. Thus if one could break the -S-S- linkages without affecting any other part of the molecule, it should be possible to split the insulin into its separate poly-peptide chains, two of which have terminal glycyl residues and the other two phenylalanyl residues. Toennies and Homiller2 showed that the only amino-acids that are appreciably oxidized by performic acid are tryptophan, methionine and cystine, the latter reacting with five atoms of oxygen and presumably forming cysteic acid. Since insulin contains no tryptophan or methionine, this seemed a suitable way of splitting the -S-S- linkages.
- Publication:
-
Nature
- Pub Date:
- August 1947
- DOI:
- 10.1038/160295b0
- Bibcode:
- 1947Natur.160..295S