How do I see if a Cys in a peptide is free or oxidized ?

Mar 16, 2021

Sequences of Cys-containing peptides lacking “disulfide bond” (or a similar extension) contain free thiol moieties, they have to be protected from inadvertent oxidation.

e.g.

H-Tyr-Gly-Gln-Val-Pro-Met-Cys-Asp-Ala-Gly-Glu-Gln-Cys-Ala-Val-OH
free sulfhydryl groups

H-Tyr-Gly-Gln-Val-Pro-Met-Cys-Asp-Ala-Gly-Glu-Gln-Cys-Ala-Val-OH (disulfide bond)
oxidized sulfhydryls

A protocol for the reversal of inadvertent oxidation of Cys peptides can be downloaded from our website.