title: Protein carbonylation sites in bovine raw milk and processed milk products.
abstract: During thermal treatment of milk, proteins are oxidized, which may reduce the nutritional value of milk, abolish protein functions supporting human health, especially important for newborns, and yield potentially harmful products. The side chains of several amino acids can be oxidized to reactive carbonyls, which are often used to monitor oxidative stress in organisms. Here we mapped protein carbonylation sites in raw milk and different brands of pasteurized, ultra high temperature (UHT) treated milk, and infant formulas (IFs) after digesting the precipitated proteins with trypsin. Reactive carbonyls were derivatized with O-(biotinylcarbazoylmethyl)hydroxylamine to enrich the modified peptides by avidin-biotin affinity chromatography and analyze them by nanoRP-UPLC-ESI-MS. Overall, 53 unique carbonylated peptides (37 carbonylation sites, 15 proteins) were identified. Most carbonyls were derived from dicarbonyls (mainly glyoxal). The number of carbonylation sites increased with the harsher processing from raw milk (4) to pasteurized (16) and UHT milk (16) and to IF (24).
authors.affiliation: Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, Leipzig, Germany; Center for Biotechnology and Biomedicine, Universität Leipzig, Leipzig, Germany.
authors.forename: Sanja
authors.initials: S
authors.lastname: Milkovska-Stamenova
authors.affiliation: Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, Leipzig, Germany; Center for Biotechnology and Biomedicine, Universität Leipzig, Leipzig, Germany.
authors.forename: Ruzanna
authors.initials: R
authors.lastname: Mnatsakanyan
authors.affiliation: Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, Leipzig, Germany; Center for Biotechnology and Biomedicine, Universität Leipzig, Leipzig, Germany. Electronic address: bioanaly@rz.uni-leipzig.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Hoffmann
mesh_terms: D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000737:chemistry; D002846:Chromatography, Affinity; D006358:Hot Temperature; D041943:Infant Formula / Q000737:chemistry*; D008892:Milk / Q000737:chemistry*; D010084:Oxidation-Reduction; D061352:Pasteurization; D010455:Peptides / Q000032:analysis* / Q000737:chemistry; D050050:Protein Carbonylation; D011492:Protein Hydrolysates / Q000032:analysis / Q000737:chemistry; D014357:Trypsin
chemical_list: D010455:Peptides; D011492:Protein Hydrolysates; C074188:O-(biotinylcarbazoylmethyl)hydroxylamine; D001710:Biotin; D014357:Trypsin
keywords: Aldehyde reactive probe; Glyoxal; Infant formula; Milk proteomics; Oxidation; Protein carbonylation