title: Modification of cysteine residue in transthyretin and a synthetic peptide: analyses by electrospray ionization mass spectrometry.
abstract: Cysteine and cystine in protein are modified to various derivatives in vitro and in vivo. By electrospray ionization mass spectrometry (ESI-MS), we previously found derivatives of serum transthyretin (TTR) in which cysteine residue at position 10 was changed to glycine residue and sulfocysteine residue. The change, cysteine to glycine, was unique and the origin of the sulfonic acid group was controversial. In the present paper, we show the molecular masses of various TTR derivatives including these two, and the modification process was studied using a synthetic peptide with the same sequence as cysteine containing part of TTR, i.e., SKCPLMVK. After incubation of the peptide at pH 8.3, various derivatives were generated, which showed changes of cysteine residue to glycine, dehydroalanine, S-thiocysteine, and S-sulfocysteine residues, which were confirmed by molecular mass and collision-induced dissociation spectra. Dehydroalanine may react with other amino acids and contribute to form cross-linking fibril, causing amyloidosis.
authors.affiliation: Department of Clinical Pathology, Osaka Medical College, 2-7 Daigaku-cho, Takatsuki City, Osaka 569-8686, Japan.
authors.forename: Toyofumi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Takako
authors.initials: T
authors.lastname: Sato
authors.forename: Saburo
authors.initials: S
authors.lastname: Sakoda
authors.forename: Masanori
authors.initials: M
authors.lastname: Yoshioka
authors.forename: Akira
authors.initials: A
authors.lastname: Shimizu
mesh_terms: D003545:Cysteine / Q000737:chemistry / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D010455:Peptides / Q000737:chemistry*; D011228:Prealbumin / Q000737:chemistry / Q000235:genetics*; D021241:Spectrometry, Mass, Electrospray Ionization; D013997:Time Factors
chemical_list: D010455:Peptides; D011228:Prealbumin; D003545:Cysteine