pH profile of cytochrome c-catalyzed tyrosine nitration.
pH profile of cytochrome c-catalyzed tyrosine nitration.
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DOI：
10.18388/abp.2006_3330
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发表时间：
2006
影响因子：
1.7
通讯作者：
Yasuhiro Kambayashi;Yoshiaki Hitomi;Norio Kodama;M. Kubo;Junna Okuda;Kei Takemoto;M. Shibamori;T. Takigawa;K. Ogino
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文献类型：
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作者：
Yasuhiro Kambayashi;Yoshiaki Hitomi;Norio Kodama;M. Kubo;Junna Okuda;Kei Takemoto;M. Shibamori;T. Takigawa;K. Ogino
在本研究中，我们研究了细胞色素c在不同ph值下如何催化酪氨酸的硝化作用。过氧化氢、亚硝酸盐和细胞色素c的浓度与细胞色素c催化酪氨酸的硝化作用成正比，过氧化氢酶、叠氮化钠、半胱氨酸和尿酸均抑制细胞色素c催化酪氨酸的硝化作用。这些结果表明，细胞色素c催化的硝基酪氨酸的形成是由于过氧化物酶的活性。pH值为6（37℃）时，细胞色素c与过氧化氢在pH值3 ~ 8范围内的反应速率常数最大。在pH为5时，硝基酪氨酸的生成量最大。在pH为3时，只有在亚硝酸盐存在的情况下，酪氨酸才发生不依赖于细胞色素的硝化作用。在这个pH值下，亚硝酸盐改变了细胞色素c的紫外和可见光谱，甚至在过氧化氢存在的情况下，可能是通过形成血红素铁一氧化氮复合物。由于这种变化，细胞色素c的过氧化物酶活性丧失。
In the present study, we investigated how cytochrome c catalyzed the nitration of tyrosine at various pHs. The cytochrome c-catalyzed nitration of tyrosine occurred in proportion to the concentration of hydrogen peroxide, nitrite or cytochrome c. The cytochromec-catalyzed nitration of tyrosine was inhibited by catalase, sodium azide, cystein, and uric acid. These results show that the cytochrome c-catalyzed nitrotyrosine formation was due to peroxidase activity. The rate constant between cytochrome c and hydrogen peroxide within the pH range of 3-8 was the largest at pH 6 (37 degrees C). The amount of nitrotyrosine formed was the greatest at pH 5. At pH 3, only cytochromec-independent nitration of tyrosine occurred in the presence of nitrite. At this pH, the UV as well as visible spectrum of cytochrome c was changed by nitrite, even in the presence of hydrogen peroxide, probably via the formation of a heme iron-nitric oxide complex. Due to this change, the peroxidase activity of cytochrome c was lost.