title: Evaluating the extent of protein damage in dairy products: simultaneous determination of early and advanced glycation-induced lysine modifications.
abstract: An isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine lysine (Lys), N(epsilon)-fructosyllysine (FL), N epsilon-carboxymethyllysine (CML), and pyrraline (Pyr) in dairy products. The presented approach entails protein cleavage via enzymatic digestion to liberate the aforementioned compounds, which were then quantified using a stable isotope dilution assay. LC-MS/MS analysis was performed by positive electrospray ionization recording two transition reactions per analyte in selected reaction monitoring mode. The CML and Lys values obtained with enzymatic digestion were compared to those acquired with acid hydrolysis HCl (6 mol/L), and the two proteolysis methods yielded comparable quantifications. Allowing for the fact that the investigated compounds are formed during different stages of the glycation process, the method is able to reveal the progress of protein glycation in dairy products.
authors.affiliation: Nestlé Research Centre, Nestec Ltd., CH-1000 Lausanne 26, Switzerland.
authors.forename: Jörg
authors.initials: J
authors.lastname: Hegele
authors.forename: Véronique
authors.initials: V
authors.lastname: Parisod
authors.forename: Janique
authors.initials: J
authors.lastname: Richoz
authors.forename: Anke
authors.initials: A
authors.lastname: Förster
authors.forename: Sarah
authors.initials: S
authors.lastname: Maurer
authors.forename: René
authors.initials: R
authors.lastname: Krause
authors.forename: Thomas
authors.initials: T
authors.lastname: Henle
authors.forename: Timo
authors.initials: T
authors.lastname: Bütler
authors.forename: Thierry
authors.initials: T
authors.lastname: Delatour
mesh_terms: D001894:Borohydrides; D002247:Carbon Isotopes / Q000032:analysis; D002853:Chromatography, Liquid; D003611:Dairy Products / Q000032:analysis*; D017127:Glycation End Products, Advanced / Q000032:analysis*; D007202:Indicators and Reagents; D008239:Lysine / Q000031:analogs & derivatives / Q000032:analysis* / Q000737:chemistry; D013058:Mass Spectrometry
chemical_list: D001894:Borohydrides; D002247:Carbon Isotopes; D017127:Glycation End Products, Advanced; D007202:Indicators and Reagents; C033186:fructosyl-lysine; C025364:sodium borohydride; D008239:Lysine