Zhang Y, Fung L W
Department of Chemistry, Loyola University of Chicago, IL 60626.
Free Radic Biol Med. 1994 Feb;16(2):215-22. doi: 10.1016/0891-5849(94)90146-5.
Fatty acid nitroxide radicals in CO-gassed erythrocytes are reduced by intracellular components with a half-life of about 160 min. In this study, using reduction rate constants of fatty acid spin labels to determine the reduction quantitatively, we found that catalase, glutathione, glutathione peroxidase, superoxide dismutase, and vitamin E--as well as hemoglobin, individually or in concerted manner, contributed little in reducing membrane nitroxides. Ascorbic acid appeared to be the predominant component in the erythrocyte to reduce membrane nitroxides. However, ascorbic acid solutions at 0.1 mM or less, concentrations similar to those found in the erythrocyte, produced no observable reduction in spin labeled membranes during the 2 h monitoring period. Ascorbic acid solutions at about 1 mM were needed to exhibit rate constants similar to those observed in labeled erythrocyte samples. It was also found that beta-nicotinamide adenine dinucleotide, beta-nicotinamide adenine dinucleotide phosphate, and heat-sensitive components in the erythrocyte enhanced the ability of ascorbic acid to scavenge nitroxide radicals in the erythrocyte membrane near the membrane surface.
一氧化碳处理过的红细胞中的脂肪酸氮氧化物自由基会被细胞内成分还原，半衰期约为160分钟。在本研究中，我们利用脂肪酸自旋标记物的还原速率常数进行定量测定，发现过氧化氢酶、谷胱甘肽、谷胱甘肽过氧化物酶、超氧化物歧化酶和维生素E，以及血红蛋白，单独或协同作用，对还原膜氮氧化物的贡献很小。抗坏血酸似乎是红细胞中还原膜氮氧化物的主要成分。然而，浓度为0.1 mM或更低的抗坏血酸溶液，类似于红细胞中的浓度，在2小时的监测期内，对自旋标记膜没有观察到明显的还原作用。需要约1 mM的抗坏血酸溶液才能表现出与标记红细胞样品中观察到的速率常数相似的速率常数。还发现，红细胞中的β-烟酰胺腺嘌呤二核苷酸、β-烟酰胺腺嘌呤二核苷酸磷酸和热敏感成分增强了抗坏血酸清除红细胞膜表面附近氮氧化物自由基的能力。
