Discrimination of ascorbate-dependent nonenzymatic and enzymatic, membrane-bound reduction of nitric oxide in denitrifying Pseudomonas perfectomarinus.
Discrimination of ascorbate-dependent nonenzymatic and enzymatic, membrane-bound reduction of nitric oxide in denitrifying Pseudomonas perfectomarinus.
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反硝化假单胞菌中抗坏血酸依赖性非酶促和酶促膜结合一氧化氮还原的区分。
DOI：
10.1016/0005-2728(82)90188-8
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
K. Frunzke
中科院分区：
文献类型：
--
作者：
W. Zumft;K. Frunzke
海洋亚硝酸盐呼吸（反硝化）细菌，完美假单胞菌，以抗坏血酸还原的吩嗪硫酸甲酯为电子供体，通过膜结合酶催化一氧化氮还原为一氧化二氮。无细胞系统的整个一氧化氮还原能力是膜结合的，并且针对 pH 值和底物依赖性对该过程进行了研究。酶促过程受到中性至碱性水溶液中抗坏血酸铁(II)的相同非酶促还原的干扰。每形成一摩尔一氧化二氮，消耗 2 摩尔一氧化氮和 1 摩尔抗坏血酸盐。酶促和非酶促过程通过它们对 pH 值和金属螯合剂的不同行为来区分。酶促反应和非酶促反应的最适pH值分别为5.2和大于7.0。 EDTA (10 mM) 完全抑制非酶还原，而不干扰膜结合活性。该非酶系统模拟一氧化氮还原酶的反应，可以作为研究反硝化过程中N-N键形成的模型。通过细胞色素cd酶促生成一氧化氮以及随后非酶促还原成一氧化二氮模拟细胞色素cd的总体准酶促一氧化二氮形成。由于在亚硝酸盐呼吸研究中普遍使用抗坏血酸以及生物样品中存在外来铁的可能性，一氧化氮的非酶还原可能在之前的工作中发生。
The marine nitrite-respiring (denitrifying) bacterium,Pseudomonas perfectomarinus,catalyzes by a membrane-bound enzyme the reduction of nitric oxide to nitrous oxide with ascorbate-reduced phenazine methosulfate as electron donor. The entire nitric oxide-reducing capability of a cell-free system was membrane bound and this process was studied with respect to pH and substrate dependency. The enzymatic process was perturbed by an identical nonenzymatic reduction by iron(II) ascorbate in neutral to alkaline aqueous solution. 2 mol nitric oxide and 1 mol ascorbate were consumed per mol nitrous oxide formed. Enzymatic and nonenzymatic processes were discriminated by their differential behavior towards pH and metal-chelating agents. The pH optimum for the enzymatic and nonenzymatic reaction was 5.2 and greater than 7.0, respectively. EDTA (10 mM) inhibited the nonenzymatic reduction completely without interfering with the membrane-bound activity. The nonenzymatic system mimics the reaction of nitric oxide reductase and could serve as a model to study the formation of the N-N bond in denitrification. Enzymatic generation of nitric oxide by cytochromecdand subsequent nonenzymatic reduction to nitrous oxide simulate an overall quasi-enzymatic nitrous oxide formation by cytochromecd. The nonenzymatic reduction of nitric oxide might have occurred in previous work due to the ubiquitous use of ascorbate in studies on nitrite respiration and the likelihood of adventitious iron in biological samples.