title: Characterization and detection of lysine-arginine cross-links derived from dehydroascorbic acid.
abstract: Covalently cross-linked proteins are among the major modifications caused by the advanced Maillard reaction. So far, the chemical nature of these aggregates is largely unknown. L-dehydroascorbic acid (DHA, 5), the oxidation product of L-ascorbic acid (vitamin C), is known as a potent glycation agent. Identification is reported for the lysine-arginine cross-links N6-[2-[(4-amino-4-carboxybutyl)amino]-5-(2-hydroxyethyl)-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (9), N6-[2-[(4-amino-4-carboxybutyl)amino]-5-(1,2-dihydroxyethyl)-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (11), and N6-[2-[(4-amino-4-carboxybutyl)amino]-5-[(1S,2S)-1,2,3-trihydroxypropyl]-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (13). The formation pathways could be established starting from dehydroascorbic acid (5), the degradation products 1,3,4-trihydroxybutan-2-one (7, L-erythrulose), 3,4-dihydroxy-2-oxobutanal (10, L-threosone), and L-threo-pentos-2-ulose (12, L-xylosone) were proven as precursors of the lysine-arginine cross-links 9, 11, and 13. Products 9 and 11 were synthesized starting from DHA 5, compound N6-[2-[(4-amino-4-carboxybutyl)amino]-5-[(1S,2R)-1,2,3-trihydroxypropyl]-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysine (16) via the precursor D-erythro-pentos-2-ulose (15). The present study revealed that the modification of lysine and arginine side chains by DHA 5 is a complex process and could involve a number of reactive carbonyl species.
authors.affiliation: Institut für Lebensmittelchemie (170), Universität Hohenheim, Garbenstr 28, D-70593 Stuttgart, Germany. oreihl@uni-hohenheim.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Reihl
authors.forename: Markus O
authors.initials: MO
authors.lastname: Lederer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schwack
mesh_terms: D001120:Arginine / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D003683:Dehydroascorbic Acid / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013780:Tetroses / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D013780:Tetroses; D001120:Arginine; D008239:Lysine; C073321:erythrose; D003683:Dehydroascorbic Acid