Wallace W, Nicholas D J
Biochem J. 1968 Oct;109(5):763-73. doi: 10.1042/bj1090763.
The reductase enzymes in Nitrosomonas and Nitrobacter were studied under anaerobic conditions when the oxidase enzymes were inactive. The most effective electron-donor systems for nitrate reductase in Nitrobacter were reduced benzyl viologen alone, phenazine methosulphate with either NADH or NADPH, and FMN or FAD with NADH. Nitrite and hydroxylamine reductases were found in both nitrifying bacteria, and optimum activity for each enzyme was obtained with NADH or NADPH with either FMN or FAD. The product of both these enzymes was identified as ammonia. In extracts of Nitrosomonas the ammonia was further utilized by an NADPH-specific glutamate dehydrogenase. (15)N-labelled nitrite, hydroxylamine and ammonia were rapidly incorporated into cell protein by Nitrosomonas, and Nitrobacter in addition incorporated [(15)N]nitrate. Relatively gentle methods of cell disruption were compared with ultrasonic treatment, to enable a more exact study to be undertaken of the intracellular distribution of the oxidase and reductase enzymes. The functional relationship of these opposing enzyme systems in the nitrifying bacteria is considered.
在厌氧条件下，当氧化酶无活性时，对亚硝化单胞菌和硝化杆菌中的还原酶进行了研究。硝化杆菌中硝酸盐还原酶最有效的电子供体系统分别是单独的还原型苄基紫精、与NADH或NADPH联用的吩嗪硫酸甲酯，以及与NADH联用的FMN或FAD。在两种硝化细菌中均发现了亚硝酸盐还原酶和羟胺还原酶，每种酶在与FMN或FAD联用的NADH或NADPH作用下获得最佳活性。这两种酶的产物均被鉴定为氨。在亚硝化单胞菌的提取物中，氨被一种NADPH特异性谷氨酸脱氢酶进一步利用。亚硝化单胞菌能迅速将(15)N标记的亚硝酸盐、羟胺和氨掺入细胞蛋白质中，硝化杆菌还能掺入[(15)N]硝酸盐。将相对温和的细胞破碎方法与超声处理进行了比较，以便能更精确地研究氧化酶和还原酶在细胞内的分布。文中还探讨了硝化细菌中这些相反酶系统的功能关系。
