Identification and quantification of phosphatidylethanolamine-derived glucosylamines and aminoketoses from human erythrocytes - Influence of glycation products on lipid peroxidation

While the Maillard reaction of amino acids and proteins as well as its cons equences in vivo has been thoroughly investigated, little attention has so far been paid to the glycation of aminophospholipids such as phosphatidylet hanolamine (PE) or phosphatidylserine (PS), which are essential for structu re and functionality of biological membranes. PE-derived glucosylamines (Sc hiff-PEs) and aminoketoses (Amadori-PEs) have now for the first time been s imultaneously identified and quantified in erythrocytes from diabetics and healthy individuals by liquid chromatography-electrospray mass spectrometry (LC-(ESI)MS). The amounts of glycated PE (gPE) were significantly higher i n diabetics (0.18-34.2 mol% Schiff-PE and 0.047-0.375 mol% Amadori-PE) than in controls (0.12-3.99 mol% Schiff-PE and 0.018-0.055 mol% Amadori-PE). A positive correlation between fructosylated hemoglobin (HbA(1c)) and the gPE levels was established, No advanced glycation endproducts (AG;Es) like 5-h ydroxymethylpyrrole-2-carbaldehyde (pyrrole-PE), carboxymethyl (CM-PE), or carboxyethyl (CE-PE) derivatives were detected. To investigate the in fluen ce of gPE on lipid peroxidation of biological membranes, liposomes consisti ng of soy-PE and synthetically prepared Amadori-PE (16:0-16:0) were incubat ed for several days and the formation of oxidation products was monitored. It could be shown that Amadori-PE extensively promotes lipid peroxidation e ven in the absence of transition metal ions like Cu2+ and Fe3+. Oxidative d amage to membrane lipids therefore is supposed to be at least partially cau sed by the glycation of aminophospholipids. (C) 2001 Academic Press.