title: Fingerprinting desmosine-containing elastin peptides.
abstract: Elastin is a vital protein of the extracellular matrix of jawed vertebrates and provides elasticity to numerous tissues. It is secreted in the form of its soluble precursor tropoelastin, which is subsequently cross-linked in the course of the elastic fiber assembly. The process involves the formation of the two tetrafunctional amino acids desmosine (DES) and isodesmosine (IDES), which are unique to elastin. The resulting high degree of cross-linking confers remarkable properties, including mechanical integrity, insolubility, and long-term stability to the protein. These characteristics hinder the structural elucidation of mature elastin. However, MS(2) data of linear and cross-linked peptides released by proteolysis can provide indirect insights into the structure of elastin. In this study, we performed energy-resolved collision-induced dissociation experiments of DES, IDES, their derivatives, and DES-/IDES-containing peptides to determine characteristic product ions. It was found that all investigated compounds yielded the same product ion clusters at elevated collision energies. Elemental composition determination using the exact masses of these ions revealed molecular formulas of the type CxHyN, suggesting that the pyridinium core of DES/IDES remains intact even at relatively high collision energies. The finding of these specific product ions enabled the development of a similarity-based scoring algorithm that was successfully applied on LC-MS/MS data of bovine elastin digests for the identification of DES-/IDES-cross-linked peptides. This approach facilitates the straightforward investigation of native cross-links in elastin.
authors.affiliation: Institute of Pharmacy, Faculty of Natural Sciences I, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
authors.forename: Christoph U
authors.initials: CU
authors.lastname: Schräder
authors.forename: Andrea
authors.initials: A
authors.lastname: Heinz
authors.forename: Petra
authors.initials: P
authors.lastname: Majovsky
authors.forename: Christian E H
authors.initials: CE
authors.lastname: Schmelzer
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000737:chemistry; D003895:Desmosine / Q000032:analysis* / Q000737:chemistry; D004549:Elastin / Q000737:chemistry*; D006801:Humans; D007524:Isodesmosine / Q000032:analysis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D008970:Molecular Weight; D009842:Oligopeptides / Q000032:analysis / Q000737:chemistry; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry; D010449:Peptide Mapping; D055550:Protein Stability / Q000187:drug effects; D059748:Proteolysis; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry; D014333:Tropoelastin / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D009842:Oligopeptides; D010446:Peptide Fragments; D014333:Tropoelastin; D003895:Desmosine; D004549:Elastin; D007524:Isodesmosine