ESR studies on reaction of saccharide with the free radicals generated from the xanthine oxidase/hypoxanthine system containing iron.
The free radicals generated from the iron containing system of xanthine oxidase and hypoxanthine (Fe-XO/HX) were directly detected by using spin trapping. It was found that not only superoxide anion (O(2)*-) and hydroxyl radical (OH*), but also alkyl or alkoxyl radicals (R*) were formed when saccharides such as glucose, fructose and sucrose were added into the Fe-XO/HX system. The generated amount of R* was dependent on the kind and concentration of saccharides added into the Fe-XO/HX system and no R* were detected in the absence of saccharides, indicating that there is an interaction between the saccharide molecules and the free radicals generated from the Fe-XO/HX system and saccharide molecules are essential for generating R* in the Fe-XO/HX system. It is expected that the toxicity of R* would be greater than of hydrophilic O(2)*- and OH* because they are liposoluble and their lives are longer and the active sites of biomolecules are closely related with lipophilic phase, thus they can damage cells more seriously than O(2)*- and OH*. The R* generated from the saccharide containing Fe-XO/HX can be effectively scavenged by selenium containing abzyme (Se-abzyme), indicating Se-abzyme is a promising antioxidant.
Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun, PR China. gmluo@mail.jlu.edu.cn
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D000818:Animals; D002241:Carbohydrates / Q000737:chemistry; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005609:Free Radicals / Q000737:chemistry*; D005632:Fructose / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry*; D019271:Hypoxanthine / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008929:Mitochondria, Heart / Q000378:metabolism; D009589:Nitrogen Oxides / Q000737:chemistry; D011725:Pyridines; D012643:Selenium / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry*; D014969:Xanthine Oxidase / Q000737:chemistry*
D002241:Carbohydrates; D005609:Free Radicals; D009589:Nitrogen Oxides; D011725:Pyridines; C043438:alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone; D019271:Hypoxanthine; D005632:Fructose; D013395:Sucrose; D007501:Iron; D014969:Xanthine Oxidase; D012643:Selenium; D005947:Glucose