Basic buffers should be avoided for peptides containing disulfide bridges. Peptides containing free thiol group may oxidize to form dimers or oligomers during storage, even as the lyophilized dry powder at a low temperature. Peptides provided as acetate salt are more sensitive to Cysteine oxidation than the corresponding TFA salt or HCL salt. The disulfide bond formation is rapid at neutral or slightly basic pH. Disulfide bridge formation is reversible. The disulfide bonds can be reduced at basic conditions using DTT. The pH 7-9.5 is the optimum pH range for reductions with DTT. The DTT solutions should be freshly prepared because DTT is readily oxidized.
