title: Heterogeneity in human cardiac troponin I standards.
abstract: The LC-MS analysis of recombinant cardiac troponin I (cTnI) and cTnI extracted from human hearts showed a high degree of structural heterogeneity among all samples. The examined recombinant cTnI samples indicated posttranslational modifications, presumably due to their purification (i.e., 2-mercaptoethanol adducts and carbamylation) and related to their expression (i.e., an N-terminal expression tag). The extracted cTnI samples, while having a higher degree of structural heterogeneity, showed less structural variance between samples than the recombinant proteins. The LC-MS analysis of the extracted cTnI samples provided evidence of posttranslational modification by phosphorylation, acetylation, proteolytic cleavage, and intrachain disulfide bond formation.
authors.affiliation: Chemical Science and Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8392, Gaithersburg, Maryland 20899, USA. david.bunk@nist.gov
authors.forename: D M
authors.initials: DM
authors.lastname: Bunk
authors.forename: J J
authors.initials: JJ
authors.lastname: Dalluge
authors.forename: M J
authors.initials: MJ
authors.lastname: Welch
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry / Q000592:standards; D013056:Spectrophotometry, Ultraviolet; D019210:Troponin I / Q000032:analysis / Q000737:chemistry / Q000592:standards*
chemical_list: D011994:Recombinant Proteins; D019210:Troponin I