Disulfide bonds in synthetic peptides

Last updated: 2026-10-10 · Research use only. Not for human or veterinary use.

Short answer

A disulfide bond is a covalent S–S link between two cysteine thiols, formed by oxidation. In synthetic peptides disulfides are created after chain assembly by air, DMSO or iodine oxidation, or by regioselective protecting-group strategies when several bridges must pair correctly. Each bond lowers the mass by about 2 Da. [1]

At a glance

Term	Definition / specification
Bond	Cys–S–S–Cys
Mass change	−2.016 Da per disulfide vs reduced form
Formation methods	Air oxidation, DMSO, iodine, orthogonal Cys protection
Confirmation	Intact MS mass shift; reduction/alkylation; MS/MS mapping
Risks	Mispaired isomers, dimers, over-oxidation
Residue	L-Cysteine, PubChem CID 5862

Multiple bridges

Peptides with two or three disulfides can form several isomers; directed pairing with protecting groups or oxidative folding conditions favour the correct one.

Reading data

Comparing mass before and after a reducing agent confirms how many bridges are present.

FAQ

How can I tell if a disulfide has formed?

The intact mass drops by about 2 Da per bond compared with the fully reduced sequence.

Can disulfides scramble?

Yes, especially at basic pH with free thiols present.

Related reference pages

Sources

Calce E et al. Air oxidation method employed for the disulfide bond formation of natural and synthetic peptides. Amino Acids. 2015. PMID: 25900810
Liu F et al. Chemical synthesis of peptides within the insulin superfamily. J Pept Sci. 2016. PMID: 26910514
Patil NA et al. Rapid Photolysis-Mediated Folding of Disulfide-Rich Peptides. Chemistry. 2019. PMID: 30924212
PubChem. L-(+)-Cysteine (C3H7NO2S, 121.16 g/mol). CID 5862

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Plain

Sable Peptides. (2026). disulfide-bonds. UK Research Peptide Reference. Retrieved 11 October 2026, from https://www.sablepeptides.co.uk/ref/disulfide-bonds

APA

Sable Peptides. (2026, October 11). *disulfide-bonds*. UK Research Peptide Reference. https://www.sablepeptides.co.uk/ref/disulfide-bonds

BibTeX

@misc{sable_disulfide-bonds_2026,
  author = {{Sable Peptides}},
  title = {{disulfide-bonds}},
  year = {2026},
  howpublished = {\url{https://www.sablepeptides.co.uk/ref/disulfide-bonds}},
  note = {Accessed 11 October 2026. CC BY 4.0}
}

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Date modified: 2026-10-16