title: The generation of superoxide anions in glycation reactions with sugars, osones, and 3-deoxyosones.
abstract: Glycoxidation is a process whereby glycated proteins chemically generate oxygen free radicals. Superoxide anion formation was measured by the superoxide dismutase-dependent reduction of ferricytochrome C in glycation reactions at pH 7.0 in the absence of transition metal ions. Assays were linear over 1 h, and most activity was seen after a 2 d incubation 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 and 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-deoxyxylosone produced 6 and 10 nmoles O.-2/hr/ml respectively with N-Ac-Lys, however, xylose was inactive, as were glucose and fructose. Glycation assays with 3-deoxyglucosone and glyoxal showed no activity, however, 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 anion in the absence of metal ions.
authors.affiliation: Mason Eye Institute, University of Missouri, Columbia, Missouri, 65212, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Ortwerth
authors.forename: H
authors.initials: H
authors.lastname: James
authors.forename: G
authors.initials: G
authors.lastname: Simpson
authors.forename: M
authors.initials: M
authors.lastname: Linetsky
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D050260:Carbohydrate Metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D006031:Glycosylation; D006861:Hydrogen Peroxide / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D013780:Tetroses / Q000378:metabolism
chemical_list: D003574:Cytochrome c Group; D017382:Reactive Oxygen Species; D013780:Tetroses; D013481:Superoxides; C002315:N(alpha)-acetyllysine; D001120:Arginine; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D012259:Ribonuclease, Pancreatic; D008239:Lysine; C073321:erythrose