| 4977982 |
Jurtshuk P, Bednarz AJ, Zey P, Denton CH: L-malate oxidation by the electron transport fraction of Azotobacter vinelandii. J Bacteriol. 1969 Jun;98(3):1120-7.
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. |
1(0,0,0,1) |