Chen K, Swartz H M
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
Biochim Biophys Acta. 1988 Jul 29;970(3):270-7. doi: 10.1016/0167-4889(88)90126-7.
In the presence of oxygen, cells can oxidize hydroxylamines, which are the products of the reduction of nitroxides in cells, back to nitroxides. Lipid-soluble hydroxylamines are oxidized much more rapidly than water-soluble ones, and most of this oxidation is inactivated by heat or trichloroacetic acid, indicating that the principal mechanism is enzyme-linked. The rates of oxidation of some lipophilic hydroxylamines are comparable to the rates of reduction of the corresponding nitroxides. Hydroxylamines formed by reduction of aqueous soluble nitroxides are not oxidized by cells, except for slight oxidation of some pyrrolidine derivatives. The latter is due to autoxidation. The kinetics of oxidation of reduced lipid-soluble nitroxides are all first-order with respect to hydroxylamines, regardless of the position of the nitroxide group along the carbon backbone, indicating that the oxidation occurs within the membrane. The oxidation of hydroxylamines in cells in inhibited by cyanide but not by antimycin A or SKF-525A. We also describe an effective method to oxidize hydroxylamines and follow this reaction; the method is based on the use of perdeuterated [15N]Tempone.
在有氧存在的情况下，细胞可以将羟胺（细胞中氮氧化物还原的产物）氧化回氮氧化物。脂溶性羟胺的氧化速度比水溶性羟胺快得多，并且这种氧化的大部分会被加热或三氯乙酸灭活，这表明主要机制是酶联的。一些亲脂性羟胺的氧化速率与相应氮氧化物的还原速率相当。由水溶性氮氧化物还原形成的羟胺不会被细胞氧化，除了一些吡咯烷衍生物有轻微氧化。后者是由于自氧化。还原的脂溶性氮氧化物的氧化动力学对于羟胺而言都是一级的，无论氮氧化物基团在碳主链上的位置如何，这表明氧化发生在膜内。细胞中羟胺的氧化受到氰化物的抑制，但不受抗霉素A或SKF - 525A的抑制。我们还描述了一种氧化羟胺并跟踪该反应的有效方法；该方法基于使用全氘代的[15N]Tempone。
