THE GENERATION OF SUPEROXIDE ANIONS IN GLYCATION REACTIONS WITH SUGARS, OSONES, AND 3-DEOXYOSONES

Glycoxidation is a process whereby glycated proteins chemically genera te oxygen free radicals. Superoxide anion formation was measured by th e superoxide dismutase-dependent reduction of ferricytochrome C in gly cation reactions at pH 7.0 in the absence of transition metal ions. As says were linear over 1 h, and most activity was seen after a 2 d incu bation of 5 mM L-threose and 10 mM alpha-N-acetyl-lysine (N-Ac-Lys) or 10 mg/mL RNase A. Trioses, tetroses and their corresponding osones an d 3-deoxyosones had the highest activity (12-16 nmoles O-2(.-)/hr/ml) with N-Ac-Lys, Osones and 3-deoxyosones alone generated considerable O -2(.-), whereas aldose sugars largely did not. Xylosone and 3-deoxyxyl osone produced 6 and 10 nmoles O-2(.-)/hr/ml respectively with N-Ac-Ly s, however, xylose was inactive, as were glucose and fructose. Glycati on assays with 3-deoxyglucosone and glyoxal showed no activity, howeve r, methyl glyoxal generated 1.7 and 2.0 nmoles O-2(.-)/hr/ml with N-Ac -Lys and N-Ac-Arg, respectively. Therefore, Amadori compounds composed of lysine and short chain sugars can rapidly generate superoxide anio n in the absence of metal ions. (C) 1998 Academic Press.