Jurtshuk P, Bednarz A J, Zey P, Denton C H
J Bacteriol. 1969 Jun;98(3):1120-7. doi: 10.1128/jb.98.3.1120-1127.1969.
The membrane-bound l-malate oxidoreductase of Azotobacter vinelandii strain O was found to be a flavoprotein-dependent enzyme associated with the electron transport system (R(3)) of this organism. The particulate R(3) fraction, which possessed the l-malate oxidoreductase, carried out the cyanide-sensitive oxidation of l-malate, d-lactate, reduced nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate, succinate, cytochrome c, tetramethyl-p-phenylenediamine, and p-phenylenediamine, with molecular O(2) as the terminal electron acceptor. d-Malate was not oxidized, but l-malate was oxidized to oxalacetate. Phenazine methosulfate (PMS), vitamin K(3), K(3)Fe(CN)(6), nitro blue tetrazolium, and dichloroindophenol all served as good terminal electron acceptors for the l-malate oxidoreductase. Cytochrome c was a poor electron acceptor. Extensive studies on the l-malate oxidase and PMS and K(3) reductases revealed that all were stimulated specifically by flavine adenine dinucleotide and nonspecifically by di- or trivalent cations, i.e., Ca(++), Ba(++), Mn(++), Mg(++), Fe(+++), Ni(++), and Al(+++). All these activities were markedly sensitive to ethylenediaminetetraacetate (EDTA). The V(max) values for the l-malate oxidase, PMS, and vitamin K(3) reductases were, respectively, 3.4, 15.1, and 45.5 mumoles of substrate oxidized per min per mg of protein at 37 C. Spectral studies revealed that the Azotobacter R(3) flavoprotein and cytochromes (a(2), a(1), b(1), c(4), and c(5)) were reduced by l-malate. l-Malate oxidase activity was sensitive to various inhibitors of the electron transport system, namely, p-chloromercuriphenylsulfonic acid, chlorpromazine, 2-n-heptyl-4-hydroxyquinoline-N-oxide, antimycin A, and KCN. Minor inhibitory effects were noted with the inhibitors 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, rotenone, and Amytal.
已发现维涅兰德固氮菌O菌株的膜结合L-苹果酸氧化还原酶是一种依赖黄素蛋白的酶，与该生物体的电子传递系统（R(3)）相关。含有L-苹果酸氧化还原酶的颗粒状R(3)组分能以分子氧作为末端电子受体，进行对氰化物敏感的L-苹果酸、D-乳酸、还原型烟酰胺腺嘌呤二核苷酸和烟酰胺腺嘌呤二核苷酸磷酸、琥珀酸、细胞色素c、四甲基对苯二胺和对苯二胺的氧化。D-苹果酸不被氧化，但L-苹果酸被氧化为草酰乙酸。硫酸吩嗪甲酯（PMS）、维生素K(3)、铁氰化钾（K(3)Fe(CN)(6)）、硝基蓝四唑和二氯靛酚均是L-苹果酸氧化还原酶良好的末端电子受体。细胞色素c是较差的电子受体。对L-苹果酸氧化酶以及PMS和K(3)还原酶的广泛研究表明，它们均受到黄素腺嘌呤二核苷酸的特异性刺激以及二价或三价阳离子（即Ca(++)、Ba(++)、Mn(++)、Mg(++)、Fe(+++)、Ni(++)和Al(+++)）的非特异性刺激。所有这些活性对乙二胺四乙酸（EDTA）均极为敏感。在37℃时，L-苹果酸氧化酶、PMS和维生素K(3)还原酶的V(max)值分别为每毫克蛋白质每分钟氧化底物3.4、15.1和45.5微摩尔。光谱研究表明，固氮菌的R(3)黄素蛋白和细胞色素（a(2)、a(1)、b(1)、c(4)和c(5)）可被L-苹果酸还原。L-苹果酸氧化酶活性对电子传递系统的各种抑制剂敏感，即对氯汞苯磺酸、氯丙嗪、2-正庚基-4-羟基喹啉-N-氧化物、抗霉素A和KCN敏感。对抑制剂4,4,4-三氟-1-(2-噻吩基)-1,3-丁二酮、鱼藤酮和阿米妥的抑制作用较小。
