Identification of disulfide-containing chemical cross-links in proteins using MALDI-TOF/TOF-mass spectrometry.

Abstract

Cross-linking can be used to identify spatial relationships between amino acids in proteins or protein complexes. A rapid and sensitive method for identifying the site of protein cross-linking using dithiobis(sulfosuccinimidyl propionate) (DTSSP) is presented and illustrated with experiments using murine cortactin, actin and acyl-CoA thioesterase. A characteristic 66 Da doublet, which arises from the asymmetric fragmentation of the disulfide of DTSSP-modified peptides, is observed in the mass spectra obtained under MALDI-TOF/TOF-MS conditions and allows rapid assignment of cross-links in modified proteins. This doublet is observed not only for linear cross-linked peptides but also in the mas..