Identification of disulfide-bridges in human serum proteins using mass spectrometry and concatenated peptide databases

摘要

A workflow for detection of endogenous disulfide-linked peptides was presented. Previously published and unpublished disulfide bridged peptides were detected; this may be due to the generation of disulfide rearrangements during sample preparation or heterogeneity of the serum. By annotation of the fragment ions observed in both the forward and reversed concatenated sequences, full sequence coverage and exact location of the disulfide bridge residues was achieved. Analysis by HCD allowed for more fragmentation and gave better utility for determination of disulfide localization than CID. ETD using a target list from the CID runs did not allow for the detection of all of the disulfide bridged peptides nor did it show any clear advantage over the peptides determined by either CID or HCD. However, the use of a target list based on CID/HCD identifications does not necessarily include the peptides best suited for ETD fragmentation.