Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. I. Stoichiometry with compounds of arsenic, selenium, tellurium, transition and other elements

Woolfolk, C. A. (University of Washington, Seattle) and H. R. Whiteley. Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. I. Stoichiometry with compounds of arsenic, selenium, tellurium, transition and other elements. J. Bacteriol. 84:647-658. 1962.-Extracts of Micrococcus lactilyticus (Veillonella alcalescens) oxidize molecular hydrogen at the expense of certain compounds of arsenic, bismuth, selenium, tellurium, lead, thallium, vanadium, manganese, iron, copper, molybdenum, tungsten, osmium, ruthenium, gold, silver, and uranium, as well as molecular oxygen. Chemical and manometric data indicate that the following reductions are essentially quantitative: arsenate to arsenite, pentavalent and trivalent bismuth to the free element, selenite via elemental selenium to selenide, tellurate and tellurite to tellurium, lead dioxide and manganese dioxide to the divalent state, ferric to ferrous iron, osmium tetroxide to osmate ion, osmium dioxide and trivalent osmium to the metal, uranyl uranium to the tetravalent state, vanadate to the level of vanadyl, and polymolybdate ions to molybdenum blues with an average valence for molybdenum of +5. The results of a study of certain other hydrogenase-containing bacteria with respect to their ability to carry out some of the same reactions are also presented.

Hydrogenase and nitrogenase in cell-free extracts of Bacillus polymyxa

Grau, F. H. (University of Wisconsin, Madison), and P. W. Wilson. Hydrogenase and nitrogenase in cell-free extracts of Bacillus polymyxa. J. Bacteriol. 85:446-450. 1963.-Washed cells of Bacillus polymyxa strain Hino, treated with lysozyme, yield cell-free extracts that rapidly evolve hydrogen from reduced methyl viologen, formate, and pyruvate. Hydrogenase is particulate, 86% being sedimented at 105,000 x g for 60 min. About 65% of the pyruvate metabolized is oxidized to acetyl phosphate, hydrogen, and carbon dioxide; the rest is converted to acetoin. These extracts fix considerable amounts of N(2) (15) when pyruvate is supplied as substrate, but will not fix with formate or mannitol. Centrifugation studies, and the absence of fixation with mannitol, show that this fixation is not caused by residual whole cells or spheroplasts. Cell-free fixation by B. polymyxa is similar to that by Clostridium pasteurianum. A short time lag in fixation occurs, and an optimal concentration of pyruvate is needed for maximal fixation. Arsenate causes a strong inhibition of fixation, presumably because arsenolysis of acetyl phosphate makes high-energy phosphate unavailable for the fixation process.

ENZYMES OF THE PYRIMIDINE PATHWAY IN ESCHERICHIA COLI. II. INTRACELLULAR LOCALIZATION AND PROPERTIES OF DIHYDROOROTIC DEHYDROGENASE

Taylor, W. Herman (Portland State College, Portland, Ore.), and Mary L. Taylor. Enzymes of the pyrimidine pathway in Escherichia coli. II. Intracellular localization and properties of dihydroorotic dehydrogenase. J. Bacteriol. 88:105-111. 1964.-Intracellular localization of three enzymes of the pyrimidine pathway in Escherichia coli was studied. Dihydroorotic dehydrogenase was found to be associated with the membrane portion of lysed spheroplasts. Centrifugal fractionation of cell-free extracts showed all the dihydroorotic dehydrogenase activity to be associated with large structures, probably cell wall-membrane fragments. In contrast, all orotidylic decarboxylase activity was found in the cytoplasm in both lysed spheroplasts and cell-free extracts. Aspartate transcarbamylase activity appeared to be particulate in repressed cells, but only 25% was particulate in derepressed cells. Dihydroorotic dehydrogenase was shown to be bound to oxidative particles by oxygen uptake and orotate production from dihydroorotate. A ferricyanide reduction assay, suitable for measuring soluble and particulate enzyme, was devised for dihydroorotic dehydrogenase. Soluble dihydroorotic dehydrogenase was prepared by use of deoxycholate. A 20-fold purification of the enzyme compared to whole-cell activity was achieved by ammonium sulfate fractionation of the deoxycholate-soluble enzyme. Although cytochromes were implicated by cyanide inhibition of aerobic orotate production by particles, the purified enzyme appeared to be separated from the cytochromes, as shown by lack of cyanide inhibition in the ferricyanide assay. The purified soluble enzyme did not react in the aerobic assay previously used by others for assay of this enzyme. In contrast to the degradative dihydroorotic dehydrogenases reported by other workers, the biosynthetic dihydroorotic dehydrogenase of E. coli did not link to pyridine nucleotides.

THE EFFECT OF DISULPHIDES ON MITOCHONDRIAL OXIDATIONS

1. Nicotinamide nucleotide-linked mitochondrial oxidations were inhibited by the disulphides NNN'N'-tetraethylcystamine, cystamine and cystine diethyl ester, whereas l-homocystine, oxidized mercaptoethanol, oxidized glutathione, NN'-diacetylcystamine and tetrathionate were only slightly inhibitory. Mitochondrial oxidations were not blocked by the thiol cysteamine. 2. NAD-independent oxidations were not inhibited by cystamine. The oxidation of choline was initially stimulated. 3. The inactivation of isocitrate, malate and beta-hydroxybutyrate oxidation of intact mitochondria could be partially reversed by external NAD. For the reactivation of alpha-oxoglutarate oxidation a thiol was also required. 4. A leakage of nicotinamide nucleotides from the mitochondria is suggested as the main cause of the inhibition. In addition, a strong inhibition of alpha-oxoglutarate dehydrogenase by cystamine was observed. A mixed disulphide formation with CoA and possibly also lipoic acid and lipoyl dehydrogenase is suggested to explain this inhibition.

THE CONTROL OF SULPHATE REDUCTION IN BACTERIA

1. An enzyme from Escherichia coli 9723 that reduces adenosine 3'-phosphate 5'-sulphatophosphate to inorganic sulphite is described. Extracts of E. coli K(12) and Bacillus subtilis 1379 contain a similar enzyme. 2. This reductase and sulphite reductase (EC 1.8.1.2) of E. coli 9723, E. coli K(12) and of B. subtilis are repressed by growth in the presence of l-cystine. Cysteine synthase (EC 4.2.1.22) is unaffected. 3. Growth of E. coli 9723 on inorganic sulphite represses the sulphate-activating enzymes (EC 2.7.7.4 and 2.7.1.25) almost completely but has little effect on sulphite reductase. Growth on 0.042-0.056mm-l-cystine gives a similar result. 4. Such differential repression by cyst(e)ine prevents E. coli, when growing on sulphite, from synthesizing unnecessary enzymes.

BRAIN MITOCHONDRIA. II. THE RELATIONSHIP OF BRAIN MITOCHONDRIA TO GLYCOLYSIS

A mitochondrial fraction prepared from calf brain cortex possessed negligible glycolytic activity in the absence of the enzymes of the high speed supernatant fraction. When mitochondria were added to a supernatant system supplemented with optimal amounts of crystalline hexokinase, a 20 per cent stimulation of glycolysis was observed. The supernatant fraction produced minimal amounts of lactate in the absence of exogenous hexokinase; the addition of mitochondria doubled the lactate production. The substitution of glycolytic intermediates for glucose as substrates as well as the addition of exogenous glycolytic enzymes to the supernatant fraction or supernatant fraction plus mitochondria indicated that the mitochondria contributed mainly hexokinase and phosphofructokinase. By direct assay of all of the enzymes of the glycolytic pathway, only hexokinase and phosphofructokinase were shown to be concentrated in the mitochondrial fraction. All other glycolytic enzymes were found to exhibit higher total and specific activities in the supernatant fraction.

ENZYMATIC ACTIVITIES OF STREPTOMYCIN-DEPENDENT ESCHERICHIA COLI IN RELATION TO VALINE FORMATION

Bragg, P. D. (University of British Columbia, Vancouver, B.C., Canada), and W. J. Polglase. Enzymatic activities of streptomycin-dependent Escherichia coli in relation to valine formation. J. Bacteriol. 88:1399-1402. 1964.-The activities of several enzymes were compared in antibiotic-depleted and antibiotic-supplemented streptomycin-dependent Escherichia coli. Depleted cells were somewhat lower than supplemented cells in several oxidase activities. Isocitric dehydrogenase was very much lower in depleted cells than in supplemented cells. The lactic dehydrogenase activity of depleted and supplemented cells was similar. The balance of enzymatic activities in depleted and supplemented cells was thus found to correlate well with the observed extracellular products. Thus, depleted cells excreted lactic acid and were deficient in oxidase activity (although normal in lactic dehydrogenase activity), whereas supplemented cells excreted valine and were rich in the reduced nicotinamide adenine dinucleotide phosphate-producing enzyme, isocitric dehydrogenase. Since antibiotic-depleted cells were not deficient in lactic dehydrogenase, it appeared probable that the failure of depleted cells to metabolize lactate was related to a deficiency in the electron-transport system.

INHIBITORY ACTION OF PHAGE K ON STAPHYLOCOCCAL DEHYDROGENASES. I. EFFECT ON VARIOUS STRAINS OF STAPHYLOCOCCUS AUREUS, INCLUDING MEMBERS OF THE PHAGE-TYPING SERIES

Ralston, D. J. (University of California, Berkeley) and B. S. Baer. Inhibitory action of phage K on staphylococcal dehydrogenases. I. Effect on various strains of Staphylococcus aureus, including members of the phage-typing series. J. Bacteriol. 86:666-672. 1963.-The polyvalent phage K was found to depress the dehydrogenase activities of a large number of Staphylococcus aureus strains, as measured by the reduction of triphenyl tetrazolium chloride to the insoluble red formazan. The inhibition occurred immediately after the absorption of a multiplicity of phage particles, and was independent of the infectibility of the strains and of the killing ability of the phage. It appeared to be closely associated with the phenomenon of sensitization-a change in the cell surface which increased the susceptibility of the wall to digestion by soluble staphylococcal lysins and simultaneously abolished the capacity to synthesize phage. The inhibitory effect occurred both in nutrient media and in a nongrowth glucose - phosphate buffer supplemented with cysteine.

BIOSYNTHESIS OF SERINE IN ESCHERICHIA COLI AND SALMONELLA TYPHIMURIUM

Umbarger, H. E. (Long Island Biological Association, Cold Spring Harbor, N.Y.), Merle A. Umbarger, and Patrick M. L. Siu. Biosynthesis of serine in Escherichia coli and Salmonella typhimurium. J. Bacteriol. 85:1431-1439. 1963.-Evidence for the operation in extracts of Escherichia coli of a pathway from glucose to serine involving 3-phosphoglycerate, phosphohydroxypyruvate, and phosphoserine as intermediates was obtained by the technique of isotopic competition. The steps of the pathway were demonstrated in extracts of E. coli and Salmonella typhimurium. The first reaction was studied in the reverse of the biosynthetic direction by observing the disappearance of reduced nicotinamide adenine dinucleotide in the presence of phosphohydroxypyruvate. The enzyme catalyzing this reaction was missing in two E. coli mutants that required serine or glycine for growth and in a representative of one of two genetically distinct classes of S. typhimurium serine-glycine auxotrophs. The second reaction, the amination of phosphohydroxypyruvate, was also studied in the reverse of the biosynthetic direction using alpha-ketoglutarate as the amino acceptor in a transamination reaction with phosphoserine. The final step, the cleavage of phosphoserine, could not be catalyzed by extracts prepared from cells of S. typhimurium serine-glycine auxotrophs of the second genetic class. It has been concluded that these three reactions provide the only significant pathway to serine in these organisms.

GLYCOLIC ACID OXIDATION BY ESCHERICHIA COLI ADAPTED TO GLYCOLATE

Furuya, Akira (University of Illinois College of Medicine, Chicago) and James A. Hayashi. Glycolic acid oxidation by Escherichia coli adapted to glycolate. J. Bacteriol. 85:1124-1131. 1963.-A procedure is described for extraction and partial purification of glycolic acid oxidase from Escherichia coli adapted to grow on glycolate as the sole carbon source. Enzyme activity was assayed by oxygen uptake and by reduction of 2,6-dichlorophenol-indophenol. Glyoxylic acid was the product of glycolate oxidation by the enzyme. Enzyme activity, which diminishes rapidly on storage, shows a maximum at pH 6 to 7. We were unable to show any cofactor requirement. Compounds which inhibited glycolate oxidation and their order of inhibitory activity were: p-hydroxymercuribenzoate > sodium azide > iodoacetate and o-phenanthroline > ethylenediaminetetraacetic acid. Tests of enzyme specificity showed that the following compounds were oxidized, but at different rates: glycolate, d-lactate, l-lactate, dl-alpha-hydroxybutyrate, dl-malate, and dl-glycerate. Citrate, tartrate, and dl-beta-hydroxybutyrate were not oxidized. Potassium cyanide stimulated oxygen uptake when glycolate and lactate were oxidized. Whether the oxidations were due to different oxidases or to a single oxidase with a wide range of specificities was tested by observing the oxidation of glycolate, d-lactate, and l-lactate under various conditions. Ammonium sulfate fractionation of a crude extract did not change the relative ability to oxidize the three acids. However, the three oxidative capacities diminished at different rates during storage at 0 C for 6 days. The partially purified glycolic oxidase preparations were probably mixtures of several different oxidases.

INDUCED PROTECTION OF ADRENAL CORTEX AGAINST 7,12-DIMETHYLBENZ(ALPHA)ANTHRACENE. INFLUENCE OF ETHIONINE. INDUCTION OF MENADIONE REDUCTASE. INCORPORATION OF THYMIDINE-H3

7,12-Dimethylbenz[a]anthracene (7,12-DMBA) exerts adrenocorticolytic effects which set it apart from all other polynuclear aromatic hydrocarbons and aromatic amines which have been investigated. Adrenal damage by this compound appears to be due to its steric and electronic properties together with its unusually high solubility in lipides. Many compounds given prior to 7,12-DMBA induced protection of adrenal. The most efficient inducers of protection are flat condensed aromatics possessing 4 or 5 rings; very small doses of these compounds were required to induce protection. Other compounds devoid of these properties induced protection but large or repeated doses were necessary. All inducers of protection had to be given prior to 7,12-DMBA to prevent adrenal necrosis; when given simultaneously with, or later than, this compound adrenal apoplexy resulted. Protective aromatics and 7,12-DMBA as well induced synthesis of menadione reductase in liver. 3-Methylcholanthrene (3-MC) induced this enzyme in many normal organs including liver, lung, adrenal, and in mammary cancer as well. dl-Ethionine under appropriate conditions of time and dosage eliminated the adrenal protection induced by aromatics and also delayed the induction of menadione reductase while depressing the amount of this enzyme which was synthesized. 7,12-DMBA caused a greatly reduced incorporation of tritium from thymidine-H³ into washed acid-insoluble residue of adrenal. 3-MC given in advance mitigated the drastic effect of 7,12-DMBA on DNA synthesis and increased considerably the amount of tritium which was incorporated. The specific damage to adrenal by 7,12-DMBA is a direct effect on cells. Protection of adrenal is a secondary effect which requires induction of protein synthesis and it results in improvement in synthesis of DNA.

THE CONVERSION OF PYRIDOXINE PHOSPHATE INTO PYRIDOXAL PHOSPHATE IN ESCHERICHIA COLI

1. Evidence is presented for the presence of pyridoxine phosphate oxidase in aqueous extracts of Escherichia coli. Some comparison is made with pyridoxamine phosphate oxidase. 2. Isoniazid and iproniazid were found to combine with pyridoxal phosphate, but isoniazid did not combine with either pyridoxamine phosphate or pyridoxine phosphate. Both oxidase activities were somewhat inhibited by benzylamine and putrescine, but not by phenethylamine or cadaverine. 3. The significance of pyridoxine phosphate oxidase in cell metabolism is discussed.

THE INHIBITION OF TWO STEROID-ACTIVATED NICOTINAMIDE-ADENINE DINUCLEOTIDE (PHOSPHATE) TRANSHYDROGENASES BY FOLIC ACID AND FOLIC ACID ANTIMETABOLITES

1. It was found that steroid-mediated nicotinamide-adenine dinucleotide (phosphate) transhydrogenases can be inhibited in vitro by folic acid and its antimetabolites. The most potent inhibitor was methotrexate, a drug with a high therapeutic index against experimental cancer. 2. The inhibitions produced by a combination of folic acid and the analogues were additive, as were those between the folic acid compounds and antagonistic steroid hormones.