Peptides containing free cysteines require special care because thiol groups can oxidize during handling and storage. A peptide with one free cysteine may form dimers, while peptides with two or more free thiols may generate more complex mixtures if oxidation occurs under the wrong conditions.
Working with cysteine-containing peptides?
Use our Peptide Calculator to review the sequence and check the basic properties before planning dissolution conditions.
For additional sequence review, open the Protein/Peptide Property Calculator.
A peptide containing one free cysteine may oxidize at pH above 7 and form dimers.
Peptides containing two or more thiol groups may form mixed oxidation products if conditions are not controlled carefully.
Oxidation and disulfide formation become much more likely near neutral or slightly basic pH.
Degassed acidic solvents or low-pH buffered systems are often safer for routine dissolution than neutral or basic conditions.
If intentional disulfide bond formation is desired, pH around 7.5–8 is often used for oxidation. However, that is a controlled oxidation step, not a general dissolution condition.
If the peptide is meant to remain in reduced form, prioritize protection from oxidation. If the peptide is meant to form a disulfide bond, treat oxidation as a separate controlled process rather than letting it happen during routine reconstitution.
If your peptide contains free cysteines and requires oxidation-sensitive handling, please email sales@lifetein.com or use our quotation form.