Cyclic interconversion of methionine containing peptide between oxidized and reduced phases monitored by reversed-phase HPLC and ESI-MS/MS

► The cyclic oxidation and reduction of methionine (Met) containing peptides and proteins. ► Structural changes monitored by RP-HPLC, MALDI-TOF MS and ESI MS/MS. ► A rapid, highly efficient and universal reduction method. ► The interconversion of the Met containing peptide implies its importance during cancer signaling.