Oxidation of biological electron donors and antioxidants by a reactive lactoperoxidase metabolite from nitrite (NO2-): an EPR and spin trapping study.
Oxidation of biological electron donors and antioxidants by a reactive lactoperoxidase metabolite from nitrite (NO2-): an EPR and spin trapping study.
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亚硝酸盐 (NO2-) 中的活性乳过氧化物酶代谢物对生物电子供体和抗氧化剂的氧化：一项 EPR 和自旋捕获研究。
DOI：
10.1016/s0891-5849(98)00244-5
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发表时间：
1999
影响因子：
7.4
通讯作者：
Dillon,J
中科院分区：
文献类型：
--
作者：
Reszka,KJ;Matuszak,Z;Chignell,CF;Dillon,J
我们报告了一种来自亚硝酸盐（NO2−）的乳过氧化物酶（LPO）代谢物催化生物电子供体和抗氧化剂（如NADH、NADPH、半胱氨酸、谷胱甘肽、抗坏血酸盐和Trolox C）的单电子氧化。自由基产物的反应已被检测和鉴定使用直接EPR或EPR结合自旋捕获。虽然LPO/H2 O2单独从这些化合物中仅产生微量的自由基，但当亚硝酸盐也存在时，自由基的产率急剧增加。在pH 7的充气缓冲液中，LPO/H2 O2对NAD（P）H的亚硝酸盐依赖性氧化产生超氧自由基O2·−，其被检测为DMPO/O2 H加合物。我们提出，在LPO/H2 O2/NO2−/生物电子供体系统中，亚硝酸盐起着催化剂的作用，因为它优先被LPO氧化成强氧化性代谢产物，最有可能是二氧化氮自由基NO2，然后它比单独的LPO/H2 O2更有效地与生物底物反应。由于亚硝酸盐和过氧化物酶是无处不在的，我们的观察点在一个可能的机制，通过亚硝酸盐可能会发挥其生物和细胞毒性作用在体内，并确定一些可能受到影响的过氧化物酶/H2 O2/亚硝酸盐系统的生理目标。
We report that a lactoperoxidase (LPO) metabolite derived from nitrite (NO2−) catalyses one-electron oxidation of biological electron donors and antioxidants such as NADH, NADPH, cysteine, glutathione, ascorbate, and Trolox C. The radical products of the reaction have been detected and identified using either direct EPR or EPR combined with spin trapping. While LPO/H2O2alone generated only minute amounts of radicals from these compounds, the yield of radicals increased sharply when nitrite was also present. In aerated buffer (pH 7) the nitrite-dependent oxidation of NAD(P)H by LPO/H2O2produced superoxide radical, O2•−, which was detected as a DMPO/O2H adduct. We propose that in the LPO/H2O2/NO2−/biological electron donor systems the nitrite functions as a catalyst because of its preferential oxidation by LPO to a strongly oxidizing metabolite, most likely a nitrogen dioxide radical NO2, which then reacts with the biological substrates more efficiently than does LPO/H2O2alone. Because both nitrite and peroxidase enzymes are ubiquitous our observations point at a possible mechanism through which nitrite might exert its biological and cytotoxic action in vivo, and identify some of the physiological targets which might be affected by the peroxidase/H2O2/nitrite systems.