TYROSINE MODIFICATION BY REACTIVE NITROGEN SPECIES - A CLOSER LOOK
TYROSINE MODIFICATION BY REACTIVE NITROGEN SPECIES - A CLOSER LOOK
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DOI：
10.1006/abbi.1995.1303
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发表时间：
1995-06-01
影响因子：
3.9
通讯作者：
CROSS, CE
中科院分区：
文献类型：
--
作者：
VANDERVLIET, A;EISERICH, JP;CROSS, CE
过氧亚硝酸盐(ONOO-)是一种强氧化剂和细胞毒性物质，由一氧化氮(NO)-N-快速反应形成。和超氧化物(O-2(.-))。在中性pH下，ONOO-被部分质子化，这种质子化形式过亚硝酸(ONOOH)迅速分解为硝酸盐，生成反应活性类似于(OH)-O-的(AN)中间体(S)。和(NO2)-N-..过氧亚硝酸盐可以羟化和硝酸芳环，ONOOH对酪氨酸等苯酚的芳香族硝化反应是通过自由基机制进行的，中间产物(NO2)-N-。(NO2)-N-对酪氨酸的修饰还包括通过自由基机制进行硝化。超氧化物歧化酶或Fe3+-EDTA可促进ONOO-对苯酚的芳香族硝化反应。超氧化物歧化酶或Fe3+-EDTA可催化ONOOH的异解裂解，形成与亚硝酸根离子(NO2+)类似的硝化物种。我们研究了不同的活性氮物种对酪氨酸修饰的可能机制，包括ONOO-，3-吗啉吡喃二亚胺(SIN-1)和(NO2)-N-。酪氨酸与ONOO-反应生成3-硝基酪氨酸和二叔丁基，表明酪氨酸基的中间产物。ONOO-生成3-硝基酪氨酸和二叔丁基酪氨酸的pH依赖性表明，需要中间生成ONOOH。当H_2O_2和NaNO_2在弱酸性pH下连续生成ONOOH或与SIN-1(一种在中性pH下都释放(NO)-N-的化合物)一起生成ONOOH时，得到了定性上相似的结果。和O-2(.-)，推测产生ONOO-。然而，SIN-1得到的硝基酪氨酸的产率相对较低，这可能是因为酪氨酸自由基与(NO)-N-发生竞争反应。或O-2(.-)。可能与(NO2)-N-有关。研究了用羟基自由基清除剂对酪氨酸进行ONOO-修饰，可以提高ONOOH分解过程中的自由基产率，从而促进(NO2)-N-的生成。羟基自由基清除剂不影响(NO2)-N-对酪氨酸的修饰。通过正品ONOO-直接和轻微地抑制酪氨酸修饰。然而，当ONOO-以较慢的速度产生时，无论是SIN-I还是在酸性pH下由H_2O_2/NaNO2产生的ONOO-，都发现羟基自由基清除剂显著促进了酪氨酸的硝化。我们的结果表明，ONOO-或ONOO-生成系统通过酪氨酸自由基和(NO2)-N-的中间形成诱导酪氨酸(或蛋白质中的酪氨酸残基)的硝化。(C)1995年学术出版社。
Peroxynitrite (ONOO-) is a powerful oxidant and cytotoxic species formed by the rapid reaction between nitrogen monoxide (nitric oxide, (NO)-N-.) and superoxide (O-2(.-)). At neutral pH ONOO- is partly protonated and this protonated form, peroxynitrous acid (ONOOH), decomposes rapidly to nitrate, forming (an) intermediate(s) with reactivity similar to (OH)-O-. and (NO2)-N-.. Peroxynitrite can hydroxylate and nitrate aromatic rings, and aromatic nitration of phenols such as tyrosine by ONOOH is proposed to proceed via a radical mechanism, with intermediate formation of (NO2)-N-.. Modification of tyrosine by (NO2)-N-. also involves nitration via a radical mechanism. Aromatic nitration of phenols by ONOO- has been shown to be enhanced by superoxide dismutase or Fe3+-EDTA, which were proposed to catalyze heterolytic cleavage of ONOOH to form a nitrating species similar to the nitronium ion (NO2+). We investigated possible mechanisms of tyrosine modification by various reactive nitrogen species, including ONOO-, 3-morpholinosydnonimine (SIN-1), and (NO2)-N-.. Reaction of tyrosine with ONOO- leads to formation of 3-nitrotyrosine and dityrosine, indicating intermediate formation of tyrosyl radicals. The pH dependence of formation of both 3-nitrotyrosine and dityrosine by ONOO- suggests that intermediate formation of ONOOH is required. Qualitatively similar results were obtained when ONOOH was generated continuously by H2O2 and NaNO2 at mildy acidic pH or with SIN-1, a compound which at neutral pH releases both (NO)-N-. and O-2(.-), presumably producing ONOO-. However, relatively low yields of nitrotyrosine were obtained with SIN-1, possibly because of competing reactions of tyrosyl radicals with (NO)-N-. or O-2(.-). Possible involvement of (NO2)-N-. in tyrosine modification by ONOO- was studied using hydroxyl radical scavengers, which can increase the radical yield during decomposition of ONOOH and thereby enhance generation of (NO2)-N-.. Hydroxyl radical scavengers did not affect tyrosine modification by (NO2)-N-. directly and slightly inhibited tyrosine modification by authentic ONOO-. However, when ONOO- was produced at a slower rate, either by SIN-I or by H2O2/NaNO2 at acidic pH, hydroxyl radical scavengers were found to significantly enhance tyrosine nitration. Our results suggest that ONOO- or ONOO--generating systems induce nitration of tyrosine (or tyrosine residues in proteins) via intermediate formation of tyrosyl radicals and (NO2)-N-.. (C) 1995 Academic Press, Inc.