A fishing technology of glycated peptides

Glycation is a non enzymatic post-translational reaction between glucose and amino functions in proteins at N-terminus and/or on Lys or Arg side-chains. Amadori products are well known in food chemistry, but also as intermediates of Advanced Glycation End Products (AGEs) involved in complications of Diabetes and other neurodegenerative diseases [1]. The non enzymatic glycation of peptides and proteins in human beings occurs spontaneously in vivo but is highly pronounced when persistent and excessive levels of glucose are present in blood as in the case of diabetes: the sugar-modified peptides may modify their functional conformation and lead to lose of their normal activity. Thus, detection, isolation and sequencing of glycated peptides is crucial. Solid supports modified with a phenyl boronate (PhB) moiety can be useful tools to fish out peptide-sugar conjugates in biological fluids. In our previous work ChemMatrix® Rink (CMRR) resin modified with a lysine substituted two PhB units, PhB-Lys(PhB)-CMRR was found to be able to capture selectively peptides containing deoxyfructosyl-lysine moieties, which then can be efficiently and specifically detected by MS experiments [2]. In order to optimize this “fishing” methodology, in terms of efficiency and selectivity, we studied the capturing of deoxyfructosylated peptides (1-8) by (i) comparing the above mentioned the ChemMatrix® Rink resin (CMRR) with -Aminohexyl–Agarose resin (-AHA) and by (ii) comparing the same two resins, CMRR and - AHA, modified with mono- or di-PhB substituted Lys moieties.