Online electrochemical reduction of both inter- and intramolecular disulfide bridges in immunoglobulins

Cysteine disulfide bridges can be reduced by chemical methods, like an incubation with DTT. However, reduction with an electrochemical method has also been demonstrated. Electrochemical reduction can be implemented online, after LC separation and before mass spectrometry. For the study of antibody molecules, reduction of the intermolecular disulfide bridges between heavy and light chains has been demonstrated in literature. However, the reduction of intramolecular disulfide bridges has remained elusive. Here, we demonstrate the online electrochemical reduction of a therapeutic monoclonal antibody. The complete reduction of these molecules will facilitate the study of recombinant or natural antibodies by MS and MS/MS.