Evaluating the extent of protein damage in dairy products: simultaneous determination of early and advanced glycation-induced lysine modifications.
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.
Hegele
Jörg
J
Nestlé Research Centre, Nestec Ltd., CH-1000 Lausanne 26, Switzerland.
Parisod
Véronique
V
Richoz
Janique
J
Förster
Anke
A
Maurer
Sarah
S
Krause
René
R
Henle
Thomas
T
Bütler
Timo
T
Delatour
Thierry
T
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
D001894:Borohydrides; D002247:Carbon Isotopes; D017127:Glycation End Products, Advanced; D007202:Indicators and Reagents; C033186:fructosyl-lysine; C025364:sodium borohydride; D008239:Lysine