HYDROXYLAMINE OXIDOREDUCTASE OF NITROSOMONAS PRODUCTION OF NITRIC-OXIDE FROM HYDROXYLAMINE
HYDROXYLAMINE OXIDOREDUCTASE OF NITROSOMONAS PRODUCTION OF NITRIC-OXIDE FROM HYDROXYLAMINE
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DOI：
10.1016/0005-2744(79)90220-1
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发表时间：
1979-01-01
期刊：
影响因子：
--
通讯作者：
TERRY, KR
中科院分区：
文献类型：
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作者：
HOOPER, AB;TERRY, KR
高纯度的羟胺氧化还原酶(羟胺：氧氧化还原酶，EC 1.7.3.4)在吩嗪甲硫酸盐存在下，催化NH_2O_2氧化成NO2-和NO_3-的混合物。本工作表明，N2O和NO也是NH_2OH氧化的产物。亚硝酸盐还原酶存在于纯度较低的羟胺氧化还原酶样品中，它催化NO2-还原为NO和N2O的混合物，并以亮氨酸为电子供体。用纯化的羟胺氧化还原酶将NO2-或NO3-还原成NO(以NH2OH还原的酶或吩嗪甲硫酸盐为潜在的电子供体)的可能性被消除；在15NO2-和15NO3-存在下，15NO不产生。因此，NO似乎是由纯化的羟胺氧化还原酶氧化NH_2OH的产物，因此可能是亚硝酸盐产生的中间产物。在10~(-6)~10~(-5)M浓度范围内，Mn2+对纯化的羟胺氧化还原酶生成亚硝酸盐和硝酸盐有明显的抑制作用，同时使羟胺的脱氢速率提高3倍。Mn(II)的存在使NO的生成减少，N2O的生成增加。结果与NH_2OH氧化反应机理一致，在该反应中，(HNO)氧化态的中间化合物的氧化是通过脱氢进行的，而不是直接加入O。
As shown previously, highly purified hydroxylamine oxidoreductase (hydroxylamine:oxygen oxidoreductase, EC 1.7.3.4) from N. europaea catalyzes the aerobic oxidation of NH2OH to a mixture of NO2- and NO3- in the presence of phenazine methosulfate. The present work shows that N2O and NO are also products of the oxidation of NH2OH. A nitrite reductase, present in less purified samples of the hydroxylamine oxidoreductase, catalyzes the reduction of NO2- to a mixture of NO and N2O with leucopyocyanine as electron donor. The possible reduction, by purified hydroxylamine oxidoreductase, of NO2- or NO3- to form NO (with NH2OH-reduced enzyme or phenazine methosulfate as potential electron donors) was eliminated; 15NO was not produced in the presence of 15NO2- and 15NO3-. NO thus appears to be a product of NH2OH oxidation by purified hydroxylamine oxidoreductase and is thus a possible intermediate in the production of nitrite. MN2+ in the concentration range 10-6-10-5 M progressively and completely inhibits the formation of nitrite and nitrate by purified hydroxylamine oxidoreductase while concomitantly stimulating the rate of dehydrogenation of hydroxylamine 3-fold. The presence of Mn(II) results in decreased formation of NO and increased formation of N2O. The present results are consistent with a mechanism of NH2OH oxidation in which the oxidation of an intermediate compound of the oxidation state of (HNO) occurs by dehydrogenation rather than direct addition of O. The dehydrogenation step is inhibited in the presence of Mn(II).