title: Mass spectrometric evidence of malonaldehyde and 4-hydroxynonenal adductions to radical-scavenging soy peptides.
abstract: Antioxidative peptides in food systems are potential targets of lipid oxidation-generated reactive aldehydes, such as malonaldehyde (MDA) and 4-hydroxynonenal (HNE). In this study, covalent modifications on radical-scavenging peptides prepared from soy protein hydrolysate by MDA and HNE were characterized by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). MS/MS analyses detected the formation of Schiff base type adducts of MDA on the side-chain groups of lysine, histidine, arginine, glutamine, and asparagine residues as well as the N-termini of peptides. MDA also formed a fluorescent product with lysine residues. HNE adducted on lysine residues through Schiff base formation and on histidine, arginine, glutamine, and asparagine residues mainly through Michael addition. Despite the extensive MDA modification, peptide cross-linking by this potential mechanism was undetectable.
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky 40546, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Haining
authors.initials: H
authors.lastname: Zhu
authors.forename: Youling L
authors.initials: YL
authors.lastname: Xiong
mesh_terms: D000447:Aldehydes / Q000032:analysis* / Q000737:chemistry; D000596:Amino Acids / Q000032:analysis / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods; D003432:Cross-Linking Reagents / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry; D008315:Malondialdehyde / Q000032:analysis* / Q000737:chemistry; D012545:Schiff Bases; D030262:Soybean Proteins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D000447:Aldehydes; D000596:Amino Acids; D003432:Cross-Linking Reagents; D016166:Free Radical Scavengers; D012545:Schiff Bases; D030262:Soybean Proteins; D008315:Malondialdehyde; C027576:4-hydroxy-2-nonenal; D008239:Lysine