Oxidative deamination of lysine residue in plasma protein from diabetic rat: alpha-dicarbonyl-mediated mechanism

摘要

The lysine residue of bovine serum albumin was dearninated to allysine (alpha-aminoadipic-delta-semialdehyde) during the incubation with glucose, 3-deoxyglucosone (3-DG), and methylglyoxal (MG) in the presence of Cu~(2+) at a physiological pH and temperature but not with glyoxal. Further, glucose, 3-DG, and MG oxidatively dearninated benzylamine to benzaldehyde in the presence of Cu~(2+). The formation of benzaldehyde was greatest with Cu~(2+), and was accelerated in the presence of oxygen. EDTA, catalase, and dimethyl sulfoxide (DMSO) significantly inhibited the oxidation. Analysis of plasma proteins revealed significantly higher levels of allysine in streptozotocin (STZ)-induced diabetic rats compared with normal controls. From these findings, wepropose a novel mechanism for the oxidative modification of proteins in diabetes via the Maillard reaction.