FREE RADICAL METABOLITE FORMATION BY PEROXIDASES

本研究的目的是检测、定量和识别 内源性和外源性化学物质产生的自由基代谢产物 通过过氧化物酶。 电子自旋共振（ESR）研究 前列腺素氢过氧化物酶和模型酶系统辣根 过氧化物酶，已经证明了自由基的酶促形成 代谢物。 研究了辣根氧化联苯胺的反应 过氧化物酶和前列腺素合酶。 联苯胺被代谢为 自由基阳离子和由联苯胺组成的电荷转移络合物， 其双电子（二亚胺）氧化产物。 二亚胺是一种共振 氮离子的结构，被认为是最终的致癌物质 芳香胺的代谢物。 ESR，在毫秒时间尺度上， 揭示了在反应中形成的瞬态苯氧基自由基， 对乙酰氨基酚与辣根过氧化物酶/H202和牛 乳过氧化物酶/H202。 短命的激进派明显区别于 从持久的顺磁性黑色素聚合物， 在存在氧化剂的情况下延长对乙酰氨基酚的孵育 内切酶 公羊精囊和对乙酰氨基酚在快速流动条件下 证明了对乙酰氨基酚氧化为苯氧基自由基， 哺乳动物的前列腺素氢过氧化物酶。 无硫心 当半胱氨酸与辣根一起孵育时， 过氧化物酶和H2 O2。 在分子氧或 过氧化氢，硫酰基自由基转化为半胱氨酸磺酸， 和亚磺酸。 还原型谷胱甘肽（GSH）也被氧化为 硫中心自由基（GS.）辣根过氧化物酶和H2 O2。 以来 半胱氨酸和谷胱甘肽在结构中起重要作用， 含巯基蛋白质的功能，这些氧化反应可能 调节这些化合物的生物学功能。

The objectives of this investigation are to detect, quantitate and identify free radical metabolites generated from endogenous and exogenous chemicals by peroxidase enzymes. Electron spin resonance (ESR) investigations of the prostaglandin hydroperoxidase and a model enzyme system, horseradish peroxidase, have demonstrated the enzymatic formation of free radical metabolites. The oxidation of benzidine was studied using horesradish peroxidase and prostaglandin synthase. Benzidine was metabolized to a radical cation and a charge-transfer complex composed of the benzidine and its two-electron (di-imine) oxidation product. The di-imine is a resonance structure of the nitrenium ion, the proposed ultimate carcinogenic metabolite of aromatic amines. ESR, on a millisecond time scale, has revealed the formation of a transient phenoxyl radical in the reaction of acetaminophen with horseradish peroxidase/H202 and bovine lactoperoxidase/H202. The short-lived radical is clearly distinguished from the persistent paramagnetic melanin polymers that are generated by prolonged incubation of acetaminophen in the presence of oxidizing enzymes. Ram seminal vesicles and acetaminophen under fast-flow conditions demonstrated the oxidation of acetaminophen to its phenoxyl free radical by the mammalian enzyme prostaglandin hydroperoxidase. Sulfur-centered free radicals have been detected when cysteine was incubated with horseradish peroxidase and H202. In the presence of either molecular oxygen or hydrogen peroxide, the thiyl radical is converted to the cysteine sulfonic and sulfinic acids. Reduced glutathione (GSH) was also oxidized to a sulfur-centered radical (GS.) by horseradish peroxidase and H202. Since cysteine and glutathione play an important role in the structure and function of sulfhydryl-containing proteins, these oxidation reactions may modulate the biological function of these compounds.