Identification of the disulfide-linked peptide in irreversibly sickled cell beta-actin

The cystine-bearing peptide complex, irreversibly sickled cell (ISC) beta-actin tryptic cytine-peptide (KFC-CDVDIR), was prepared, characterized by spectroscopy and chromatography, and identified in the tryptic digest of ISC beta-actin by mass spectrometry. Interestingly, cysteines284 and 373 of the ISC beta-actin are indeed linked by a disulfide bridge. The carboxy end of actin rearranges upon dissociation of the accompanying protein. This results to the solvent orientation of C373 side segment and the predisposal of C373 and C284 portions to the formation of disulfide bond.