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Abstract
Production of hydrogen by anaerobes, facultative anaerobes, aerobes, methylotrophs, and photosynthetic bacteria is possible. Anaerobic Clostridia are potential producers and immobilized C. butyricum produces 2 mol H2/mol glucose at 50% efficiency. Spontaneous production of H2 from formate and glucose by immobilized Escherichia coli showed 100% and 60% efficiencies, respectively. Enterobactericiae produces H2 at similar efficiency from different monosaccharides during growth. Among methylotrophs, methanogenes, rumen bacteria, and thermophilic archae, Ruminococcus albus, is promising (2.37 mol/mol glucose). Immobilized aerobic Bacillus licheniformis optimally produces 0.7 mol H2/mol glucose. Photosynthetic Rhodospirillum rubrum produces 4, 7, and 6 mol of H2 from acetate, succinate, and malate, respectively. Excellent productivity (6.2 mol H2/mol glucose) by co-cultures of Cellulomonas with a hydrogenase uptake (Hup) mutant of R. capsulata on cellulose was found. Cyanobacteria, viz., Anabaena, Synechococcus, and Oscillatoria sp., have been studied for photoproduction of H2. Immobilized A. cylindrica produces H2 (20 ml/g dry wt/h) continually for 1 year. Increased H2 productivity was found for Hup mutant of A. variabilis. Synechococcus sp. has a high potential for H2 production in fermentors and outdoor cultures. Simultaneous productions of oxychemicals and H2 by Klebseilla sp. and by enzymatic methods were also attempted. The fate of H2 biotechnology is presumed to be dictated by the stock of fossil fuel and state of pollution in future.
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Affiliation(s)
- R Nandi
- Department of Applied Biochemistry, Indian Institute of Chemical Biology, Calcutta, India
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Ludden PW, Roberts GP. Regulation of nitrogenase activity by reversible ADP ribosylation. CURRENT TOPICS IN CELLULAR REGULATION 1989; 30:23-56. [PMID: 2575970 DOI: 10.1016/b978-0-12-152830-0.50004-9] [Citation(s) in RCA: 101] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- P W Ludden
- Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706
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Abstract
The photosynthetic prokaryotes possess diverse metabolic capabilities, both in carrying out different types of photosynthesis and in their other growth modes. The nature of the coupling of these energy-generating processes with the basic metabolic demands of the cell, such as nitrogen fixation, has stimulated research for many years. In addition, nitrogen fixation by photosynthetic prokaryotes exhibits several unique features; the oxygen-evolving cyanobacteria have developed various strategies for protection of the oxygen-labile nitrogenase proteins, and some photosynthetic bacteria have been found to regulate their nitrogenase (N2ase) activity in a rapid response to fixed nitrogen, thus saving substantial amounts of energy. Recent advances in the biochemistry, physiology, and genetics of nitrogen fixation by cyanobacteria and photosynthetic bacteria are reviewed, with special emphasis on the unique features found in these organisms. Several major topics in cyanobacterial nitrogen fixation are reviewed. The isolation and characterization of N2ase and the isolation and sequence of N2ase structural genes have shown a great deal of similarity with other organisms. The possible pathways of electron flow to N2ase, the mechanisms of oxygen protection, and the control of nif expression and heterocyst differentiation will be discussed. Several recent advances in the physiology and biochemistry of nitrogen fixation by the photosynthetic bacteria are reviewed. Photosynthetic bacteria have been found to fix nitrogen microaerobically in darkness. The regulation of nif expression and possible pathways of electron flow to N2ase are discussed. The isolation of N2ase proteins, particularly the covalent modification of the Fe protein, the nature of the modifying group, properties of the activating enzyme, and regulating factors of the inactivation/activation process are reviewed.
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Vignais PM, Colbeau A, Willison JC, Jouanneau Y. Hydrogenase, nitrogenase, and hydrogen metabolism in the photosynthetic bacteria. Adv Microb Physiol 1985; 26:155-234. [PMID: 3913292 DOI: 10.1016/s0065-2911(08)60397-5] [Citation(s) in RCA: 119] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Nordlund S, Norén A. Dependence on divalent cations of the activation of inactive Fe-protein of nitrogenase from rhodospirillum rubrum. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0167-4838(84)90276-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kanemoto RH, Ludden PW. Effect of ammonia, darkness, and phenazine methosulfate on whole-cell nitrogenase activity and Fe protein modification in Rhodospirillum rubrum. J Bacteriol 1984; 158:713-20. [PMID: 6427184 PMCID: PMC215488 DOI: 10.1128/jb.158.2.713-720.1984] [Citation(s) in RCA: 159] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
A procedure for the immunoprecipitation of Fe protein from cell extracts was developed and used to monitor the modification of Fe protein in vivo. The subunit pattern of the isolated Fe protein after sodium dodecyl sulfate-polyacrylamide gel electrophoresis was assayed by Coomassie brilliant blue protein staining and autoradiographic 32P detection of the modifying group. Whole-cell nitrogenase activity was also monitored during Fe protein modification. The addition of ammonia, darkness, oxygen, carbonyl cyanide m-chlorophenylhydrazone, and phenazine methosulfate each resulted in a loss of whole-cell nitrogenase activity and the in vivo modification of Fe protein. For ammonia and darkness, the rate of loss of nitrogenase activity was similar to that for Fe protein modification. The reillumination of a culture incubated in the dark brought about a rapid recovery of nitrogenase activity and the demodification of Fe protein. Cyclic dark-light treatments resulted in matching cycles of nitrogenase activity and Fe protein modification. Carbonyl cyanide m-chlorophenylhydrazone and phenazine methosulfate treatments caused an immediate loss of nitrogenase activity, whereas Fe protein modification occurred at a slower rate. Oxygen treatment resulted in a rapid loss of activity but only an incomplete modification of the Fe protein.
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Guth JH, Burris RH. The role of Mg2+ and Mn2+ in the enzyme-catalysed activation of nitrogenase Fe protein from Rhodospirillum rubrum. Biochem J 1983; 213:741-9. [PMID: 6412690 PMCID: PMC1152191 DOI: 10.1042/bj2130741] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The activation of the Fe protein of nitrogenase (Rr2) from glutamate-grown Rhodospirillum rubrum by activating enzyme (AE) was investigated. AE is confirmed to have Mr about 20 000 and is shown to operate catalytically. There is a role in activation for metal-ion-ATP, which can be met by either MnATP or MgATP. There is also a site of action for free metal ions. This site prefers Mn2+ (apparent Kd approx. 20 microM) over Mg2+ (apparent Kd approx. 20 mM) by a factor of 1000-fold. Non-activated Rr2 does not contain this binding site. MnATP is an inhibitor of C2H2 reduction, and excess Mg2+ inhibits both AE activity and C2H2 reduction, when each is studied independently under otherwise optimal conditions. The activity of AE is increased in normal reaction mixtures (in which AE activity and nitrogenase activity occur simultaneously) by Mg2+ concentrations in excess of ATP concentrations; this occurs because the excess Mg2+ prevents ATP from chelating the free Mn2+ necessary for optimal AE activity.
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Triplett EW, Wall JD, Ludden PW. Expression of the activating enzyme and Fe protein of nitrogenase from Rhodospirillum rubrum. J Bacteriol 1982; 152:786-91. [PMID: 6813314 PMCID: PMC221530 DOI: 10.1128/jb.152.2.786-791.1982] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Activating enzyme (AE) is responsible for the in vitro activation of inactive Fe protein of nitrogenase from Rhodospirillum rubrum cells cultured anaerobically with glutamate as the N source. The expression of Fe protein and AE was examined in R. rubrum cultured photosynthetically or aerobically on media containing malate as the carbon source. One of the following N sources was used in each culture: glutamate, glutamine, limiting ammonia, high ammonia, glutamate plus histidine, and high ammonia plus histidine. Chromatophores from every culture exhibited AE activity; activity was highest in glutamate-grown cells. Fe protein was observed by rocket immunoelectrophoresis in cultures with nitrogenase activity. Several Nif-, Gln-, and His- mutants of R. rubrum were assayed for AE activity, nitrogenase activity, and Fe protein. Every mutant expressed AE activity, and Fe protein was observed in those cultures with nitrogenase activity. AE from every preparation was O2 labile, and each O2-denatured AE preparation inhibited activation by active AE.
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Gotto JW, Yoch DC. Purification and Mn2+ activation of Rhodospirillum rubrum nitrogenase activating enzyme. J Bacteriol 1982; 152:714-21. [PMID: 6813313 PMCID: PMC221521 DOI: 10.1128/jb.152.2.714-721.1982] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The Fe protein activating enzyme for Rhodospirillum rubrum nitrogenase was purified to approximately 90% homogeneity, using DE52-cellulose chromatography and sucrose density gradient centrifugation. Activating enzyme consists of a single polypeptide of molecular weight approximately 24,000. ATP was required for catalytic activity, but was relatively ineffective in the absence of Mg2+. When the concentration of MgATP2- was held in excess, there was an additional requirement for a free divalent metal ion (Mn2+) for enzyme activity. Kinetic experiments showed that the presence of Mg2+ influenced the apparent binding of Mn2+ by the enzyme, resulting in a lowering of the concentration of Mn2+ required to give half-maximum activity (K alpha) as the free Mg2+ concentration was increased. A low concentration of Mn2+ had a sparing effect on the requirement for free Mg2+. There is apparently a single metal-binding site on activating enzyme which preferentially binds Mn2+ as a positive effector, and free Mg2+ can compete for this site.
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In vivo and in vitro studies on ATP and electron donors to nitrogenase in Rhodospirillum rubrum. Arch Microbiol 1981. [DOI: 10.1007/bf00411070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Voelskow H, Sch�n G. H2 production of Rhodospirillum rubrum during adaptation to anaerobic dark conditions. Arch Microbiol 1980. [DOI: 10.1007/bf00446884] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Adams MW, Hall DO. Properties of the solubilized membrane-bound hydrogenase from the photosynthetic bacterium Rhodospirillum rubrum. Arch Biochem Biophys 1979; 195:288-99. [PMID: 224815 DOI: 10.1016/0003-9861(79)90355-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Nordlund S, Eriksson U, Baltscheffsky H. Properties of the nitrogenase system from a photosynthetic bacterium, Rhodospirillum rubrum. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 504:248-54. [PMID: 102339 DOI: 10.1016/0005-2728(78)90173-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Soluble nitrogenase from Rhodospirillum rubrum has been isolated and separated into its two components, the MoFe protein and the Fe protein. The MoFe protein has been purified to near homogeneity and has a molecular weight or 215 000. It contains two Mo, 25--30 Fe and 19--22 acid-labile sulphide and consists of four subunits, Mw 56 000. The Fe protein has a molecular weight 65 000. It contains approximately four Fe and four acid-labile sulphide and consists of two subunits, Mw 31 500. The highest specific activities for the purified components are 920 and 1260 nmol ethylene produced per min per mg protein, respectively. The purified components require the membrane component for activity (Nordlund, S., Eriksson, U. and Baltscheffsky, H. (1977) Biochim. Biophys. Acta 462, 187--195). Titration of the MoFe protein with the Fe protein shows saturation and excess MoFe protein over Fe protein is inhibitory. Addition of Fe2+ or Mn2+ to the reaction mixture increases the activity apparently through interaction with the membrane component.
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Abstract
The photosynthetic bacteria are found in a wide range of specialized aquatic environments. These bacteria represent important members of the microbial community since they are capable of carrying out two of the most important processes on earth, namely, photosynthesis and nitrogen fixation, at the expense of solar energy. Since the discovery that these bacteria could fix atmospheric nitrogen, there has been an intensification of studies relating to both the biochemistry and physiology of this process. The practical importance of this field is emphasized by a consideration of the tremendous energy input required for the production of artificial nitrogenous fertilizer. The present communication aims to briefly review the current state of knowledge relating to certain aspects of nitrogen fixation by the photosynthetic bacteria. The topics that will be discussed include a general survey of the nitrogenase system in the various photosynthetic bacteria, the regulation of both nitrogenase biosynthesis and activity, recent advances in the genetics of the nitrogen fixing system, and the hydrogen cycle in these bacteria. In addition, a brief discussion of some of some of the possible practical applications provided by the photosynthetic bacteria will be presented.
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Siefert E, Pfennig N. Hydrogen metabolism and nitrogen fixation in wild type and Nif- mutants of Rhodopseudomonas acidophila. Biochimie 1978; 60:261-5. [PMID: 667181 DOI: 10.1016/s0300-9084(78)80822-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
N2 fixation, C2H2 reduction and H2 production in Rhodopseudomonas acidophila DSM 137 were shown to be stoichiometrically related in ratios of 1:2.8:2.8. The highest possible H2 oxidation rate has been calculated to be about 6 fold higher in Rhodopseudomonas acidophila DSM 137 than the maximum rate of H2 production. Nif- mutants were isolated and tested; all of them had lost their ability of reduce C2H2 and to produce H2. In two nif- mutants hydrogenase activity and the capacity for autotrophic growth with H2 were also strongly diminished. Nif+ revertants not only regained their ability for C2H2 reduction and H2 production but also their full capacity for autotrophic growth with H2.
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Zumft WG, Castillo F. Regulatory properties of the nitrogenase from Rhodopseudomonas palustris. Arch Microbiol 1978; 117:53-60. [PMID: 678011 DOI: 10.1007/bf00689351] [Citation(s) in RCA: 129] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ammonium salts, glutamine, asparagine, and urea cause an immediate inactivation (switch-off) of light-dependent acetylene reduction in intact cells of the photosynthetic bacterium Rhodopseudomonas palustris. This effect is reversible showing the same kinetic pattern of inactivation and reactivation with all effector compounds. Its duration depends on the amount of effector added to the cells. Both nitrogenase components are found catalytically active in a cell-free preparation after enzyme switch-off in vivo. Involvement of the ammonia assimilating system in this regulatory mechanism is indicated by the following observations: ammonia uptake during the switch-off period, resumption of acetylene reduction after disappearance of ammonia from the outer medium, and persistence of enzyme switch-off with dihydrogen and thiosulfate as electron donors in the absence of an additional carbon source. Nitrogenase activity in crude extracts is non-linear with time and is stimulated by manganese ions. After resolution of nitrogenase into its MoFe--protein and Fe--protein these properties are lost, indicating the presence of an activating factor. Nitrogenase of R. palustris cross reacts reciprocally with the complementary proteins of Azotobacter vinelandii, but not with those of Clostridium pasteurianum.
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Nordlund S, Eriksson U, Baltscheffsky H. Necessity of a membrane component for nitrogenase activity in Rhodospirillum rubrum. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 462:187-95. [PMID: 410446 DOI: 10.1016/0005-2728(77)90201-8] [Citation(s) in RCA: 86] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Acetylene reduction catalyzed by nitrogenase from Rhodospirillum rubrum has low activity and exhibits a lag phase. The activity can be increased by the addition of a chromatophore membrane component and the lag eliminated by preincubation with this component, which can be solubilized from chromatophores by treatment with NaCl. It is both trypsin- and oxygen-sensitive. Titration of the membrane component with nitrogenase and vice versa shows a saturation point. The membrane component interacts specifically with the Fe protein of nitrogenase, the interaction being ATP- and Mg2+-dependent.
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Adams MW, Hall DO. Isolation of the membrane-bound hydrogenase from Rhodospirillum rubrum. Biochem Biophys Res Commun 1977; 77:730-7. [PMID: 409403 DOI: 10.1016/s0006-291x(77)80039-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Ludden PW, Burris RH. Activating factor for the iron protein of nitrogenase from Rhodospirillum rubrum. Science 1976; 194:424-6. [PMID: 824729 DOI: 10.1126/science.824729] [Citation(s) in RCA: 151] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
As isolated from Rhodospirillum rubrum, the iron protein of nitrogenase has little or no activity. It can be activated by incubating it with a trypsin-sensitive, oxygen-labile component (activating factor) plus adenosine triphosphate and a divalent metal ion. After activation, the iron protein retains its nitrogenase activity when the activating factor is removed.
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Zumft WG, Mortenson LE. The nitrogen-fixing complex of bacteria. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 416:1-52. [PMID: 164247 DOI: 10.1016/0304-4173(75)90012-9] [Citation(s) in RCA: 86] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Brown C, Macdonald-Brown DS, Meers J. Physiological Aspects of Microbial Inorganic Nitrogen Metabolism. Adv Microb Physiol 1974. [DOI: 10.1016/s0065-2911(08)60268-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ketchum PA, Sevilla CL. In vitro formation of nitrate reductase using extracts of the nitrate reductase mutant of Neurospora crassa, nit-1, and Rhodospirillum rubrum. J Bacteriol 1973; 116:600-9. [PMID: 4270447 PMCID: PMC285424 DOI: 10.1128/jb.116.2.600-609.1973] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In vitro formation of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-nitrate reductase (NADPH: nitrate oxido-reductase, EC 1.6.6.2) has been attained by using extracts of the nitrate reductase mutant of Neurospora crassa, nit-1, and extracts of either photosynthetically or heterotrophically grown Rhodospirillum rubrum, which contribute the constitutive component. The in vitro formation of NADPH-nitrate reductase is characterized by the conversion of the flavin adenine dinucleotide (FAD) stimulated NADPH-cytochrome c reductase, contributed by the N. crassa nit-1 extract from a slower sedimenting form (4.5S) to a faster sedimenting form (7.8S). The 7.8S NADPH-cytochrome c reductase peak coincides in sucrose density gradient profiles with the NADPH-nitrate reductase, FADH(2)-nitrate reductase and reduced methyl viologen (MVH)-nitrate reductase activities which are also formed in vitro. The constitutive component from R. rubrum is soluble (both in heterotrophically and photosynthetically grown cells), is stimulated by the addition of 10(-4) M Na(2)MoO(4) and 10(-2) M NaNO(3) to cell-free preparations, and has variable activity over the pH range from 3.0 to 9.5. The activity of the constitutive component in some extracts showed a threefold stimulation when the pH was lowered from 6.5 to 4.0. The constitutive activity appears to be associated with a large molecular weight component which sediments as a single peak in sucrose density gradients. However, the constitutive component from R. rubrum is dialyzable and is insensitive to trypsin and protease. These results demonstrate that R. rubrum contains the constitutive component and suggests that it is a low molecular weight, trypsin- and protease-insensitive factor which participates in the in vitro formation of NADPH nitrate reductase.
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Schick HJ. Substrate and light dependent fixation of molecular nitrogen in Rhodospirillum rubrum. ARCHIV FUR MIKROBIOLOGIE 1971; 75:89-101. [PMID: 5540223 DOI: 10.1007/bf00407997] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Winter HC, Arnon DI. The nitrogen fixation system of photosynthetic bacteria. I. Preparation and properties of a cell-free extract from Chromatium. BIOCHIMICA ET BIOPHYSICA ACTA 1970; 197:170-9. [PMID: 5416107 DOI: 10.1016/0005-2728(70)90028-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Munson TO, Burris RH. Nitrogen fixation by Rhodospirillum rubrum grown in nitrogen-limited continuous culture. J Bacteriol 1969; 97:1093-8. [PMID: 4887498 PMCID: PMC249819 DOI: 10.1128/jb.97.3.1093-1098.1969] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Cell-free extracts of the photosynthetic bacterium Rhodospirillum rubrum were inconsistent in reducing N(2). An internally illuminated fermentor, designed for the continuous culture of this organism on N(2) under nitrogen-limited conditions, produced cells which yielded cell extracts with consistent activity for cell-free N(2) fixation. A nitrogen-limited continuous culture, supplied ammonia rather than N(2), gave cell-free extracts with even more active N(2) fixation. Extracts of cells grown in the fermentor with glutamate nitrogen as the limiting nutrient in continuous culture did not reduce N(2), but whole cells fixed (15)N-enriched N(2). The discovery that cells from ammonia and glutamate nitrogen-limited continuous cultures are capable of N(2) reduction suggests that R. rubrum cells produce the N(2)-reducing enzymes in response to conditions of nitrogen deficiency rather than in response to the presence of N(2). Examination of the effect of the pN(2) on N(2) reduction by cell-free preparations of R. rubrum indicated that the K(N(2)) is approximately 0.071 atm. Cell-free extracts from R. rubrum were tested for their ability to reduce substrates other than N(2).
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Nitrogen Fixation. ACTA ACUST UNITED AC 1968. [DOI: 10.1016/b978-1-4832-0006-4.50010-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Bulen WA, LeComte JR. The nitrogenase system from Azotobacter: two-enzyme requirement for N2 reduction, ATP-dependent H2 evolution, and ATP hydrolysis. Proc Natl Acad Sci U S A 1966; 56:979-86. [PMID: 5230193 PMCID: PMC219956 DOI: 10.1073/pnas.56.3.979] [Citation(s) in RCA: 230] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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