Iannone A, Tomasi A, Vannini V, Swartz H M
University of Illinois College of Medicine, Urbana.
Biochim Biophys Acta. 1990 Jun 20;1034(3):290-3. doi: 10.1016/0304-4165(90)90053-y.
As part of an ongoing study of the role of subcellular fractions on the metabolism of nitroxides, we studied the metabolism of a set of five nitroxides in cytosol derived from rat hepatocytes. The nitroxides were chosen to provide information on the effects of the type of charge and the ring on which the nitroxyl group is located. The rates of reduction were fastest for a six-membered positively charged nitroxide ('CAT-1') and slowest for an anionic five-membered ring nitroxide ('PCA'). Changing levels of glutathione, sulphydryl groups in general, NADPH or NADH had little or no effect on the rates of reduction, while the addition of ascorbate oxidase essentially abolished reduction of the nitroxides. The products of reduction by the cytosol were the corresponding hydroxylamines. The overall rates of reduction of neutral or anionic nitroxides were much slower than those observed with intact cells. We conclude that the primary source of metabolism of nitroxides by cytosol is reduction by ascorbate and that under most conditions reduction of nitroxides in the cytosol is not a major factor in the metabolism of nitroxides by cells.
作为一项关于亚细胞组分在氮氧化物代谢中作用的持续研究的一部分，我们研究了一组五种氮氧化物在大鼠肝细胞胞质溶胶中的代谢情况。选择这些氮氧化物是为了提供有关电荷类型以及硝酰基所在环的影响的信息。六元带正电荷的氮氧化物（“CAT-1”）的还原速率最快，而阴离子五元环氮氧化物（“PCA”）的还原速率最慢。谷胱甘肽、一般巯基、NADPH或NADH水平的变化对还原速率几乎没有影响，而添加抗坏血酸氧化酶基本上消除了氮氧化物的还原。胞质溶胶还原的产物是相应的羟胺。中性或阴离子氮氧化物的总体还原速率比完整细胞中观察到的要慢得多。我们得出结论，胞质溶胶中氮氧化物代谢的主要来源是抗坏血酸的还原，并且在大多数情况下，胞质溶胶中氮氧化物的还原不是细胞中氮氧化物代谢的主要因素。
