Practical Protein Chemistry - A. Darbre 1989

Disulfide bonds
Identification and localization of cystine-containing peptides
General remarks

Assuming that the Amino Acid Sequence and the positions of most Disulfide Bonds in a protein have been established, it is obvious that the Location OF THE final disulfide bridge can be accepted without proof. For example, if the positions of three out of four bridges are determined unambiguously, it is reasonable to assume that the remaining bridge links the two unidentified half-cystine residues. As already noted, the Isolation of Cystine-containing Peptides can be accompanied by significant losses, with yields dropping below 50% in some cases. However, in the absence of contradictory evidence, even this is often quite sufficient for the unambiguous localization of S—S bridges. Naturally, this Conclusion holds true provided that the disulfide bonds remain stable within the protein molecule. A rare exception that is seldom encountered is ß-lactoglobulin [27], whose disulfide bonds are unstable.



Last update: 06/08/2026

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