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the evolution of prokaryotic ferredoxins--with a general method correcting for unobserved substitutions in less branched lineages.thirty-one bacterial type ferredoxins were examined by means of the parsimony method for their phylogenetic implications. the results show reasonable relationships in that photosynthetic, thermophilic, and desulfovibrio groups are identifiable; but a number of interesting anomalies occur. these include a methanogen sequence that clusters among the desulfovibrios. there are several differences from the phylogeny of woese. at least two duplications producing paralogous genes are demonstrated, plus ...19873447013
short-term nitrate (nitrite) inhibition of nitrogen fixation in azotobacter chroococcum.nitrate-grown azotobacter chroococcum atcc 4412 cells lack the ability to fix n2. nitrogenase activity developed after the cells were suspended in a combined nitrogen-free medium and was paralleled by a concomitant decrease in nitrate assimilation capacity. in such treated cells exhibiting transitory nitrate assimilation and n2-fixation capacity, nitrate or nitrite caused a short-term inhibitory effect on nitrogenase activity which ceased once the anion was exhausted from the medium. the analog ...19863455689
studies on the mechanism of electron transport to nitrogenase in azotobacter vinelandii.the involvement of the cytoplasmic membrane in electron transport to nitrogenase has been studied. evidence shows that nitrogenase activity in azotobacter vinelandii is coupled to the flux of electrons through the respiratory chain. to obtain information about proteins involved, the changes occurring in a. vinelandii cells transferred to nitrogen-free medium after growth on nh4cl (depression of nitrogenase activity) were studied. synthesis of the nitrogenase polypeptides was detectable 5 min aft ...19863456304
activity, reconstitution, and accumulation of nitrogenase components in azotobacter vinelandii mutant strains containing defined deletions within the nitrogenase structural gene cluster.the azotobacter vinelandii genes encoding the nitrogenase structural components are clustered and ordered: nifh (fe protein)-nifd (mofe protein alpha subunit)-nifk (mofe protein beta subunit). in this study various a. vinelandii mutant strains which contain defined deletions within the nitrogenase structural genes were isolated and studied. mutants deleted for the nifd or nifk genes were still able to accumulate significant amounts of the unaltered mofe protein subunit as well as active fe prote ...19863457004
elicitation of thiomolybdates from the iron-molybdenum cofactor of nitrogenase. comparison with synthetic fe-mo-s complexes.aerial oxidation of the iron-molybdenum cofactor (femoco) of azotobacter vinelandii nitrogenase has been shown to yield either the tetrathiomolybdate ion ([mos4]2-) or the oxotrithiomolybdate ion ([moos3]2-), depending on the reaction conditions. thus, when n-methylformamide (nmf) solutions of femoco either were titrated with measured aliquots of air or were diluted with air-saturated nmf, [moos3]2- was found to be the predominant product while dilution of nmf solutions of femoco with air-satura ...19863462002
nitrogen fixation in molybdenum-deficient continuous culture by a strain of azotobacter vinelandii carrying a deletion of the structural genes for nitrogenase (nifhdk).steady-state chemostat cultures of azotobacter vinelandii strain ca11, carrying a deletion of genes encoding the structural polypeptides of nitrogenase nifhdk, were established in a simple defined medium chemically purified to minimize contamination by mo. the medium contained no utilizable n source. growth was dependent on n2 (1.1 x 10(8) viable cells x ml-1 at d = 0.176 h-1), and was inhibited by mo (20 nm). dna hybridization showed the deletion to be stable during prolonged (55 days) growth i ...19863467721
products of the iron-molybdenum cofactor-specific biosynthetic genes, nife and nifn, are structurally homologous to the products of the nitrogenase molybdenum-iron protein genes, nifd and nifk.the genes from azotobacter vinelandii, which are homologous to the iron-molybdenum cofactor biosynthetic genes, nife and nifn, from klebsiella pneumoniae, have been cloned and sequenced. these genes comprise a single transcription unit and are located immediately downstream from the nitrogenase structural gene cluster (nifhdk). dna sequence analysis has revealed that the products of the nife and nifn genes contain considerable homology when compared with the nifd (mofe protein alpha subunit) and ...19873470285
iron-molybdenum cofactor synthesis in azotobacter vinelandii nif- mutants.nif- mutants of azotobacter vinelandii defective in dinitrogenase activity synthesized iron-molybdenum cofactor (femo-co) and accumulated it in two protein-bound forms: inactive dinitrogenase and a possible intermediate involved in the femo-co biosynthetic pathway. femo-co from both these proteins could activate apo-dinitrogenase from femo-co-deficient mutants.19873470286
characterization of the metal clusters in the nitrogenase molybdenum-iron and vanadium-iron proteins of azotobacter vinelandii using magnetic circular dichroism spectroscopy.low-temperature magnetic circular dichroism (mcd) spectroscopy has been used to investigate the metal clusters in the conventional nitrogenase mofe protein and alternative vfe protein from azotobacter vinelandii. in the dithionite-reduced state, the mcd spectrum of the mofe protein is extremely similar to that previously observed for the s = 3/2 spin state of the m clusters in the mofe protein of klebsiella pneumoniae. a paramagnetic cluster with an s = 3/2 ground state is also responsible for t ...19873474027
iron-molybdenum cofactor biosynthesis in azotobacter vinelandii requires the iron protein of nitrogenase.nitrogenase is composed of two separately purified proteins called the fe protein and the mofe protein. in azotobacter vinelandii the genes encoding these structural components are clustered and ordered: nifh (fe protein)-nifd (mofe protein alpha subunit)-nifk (mofe protein beta subunit). the mofe protein contains an ironmolybdenum cofactor (femo cofactor) whose biosynthesis involves the participation of at least five gene products, nifq, nifb, nifn, nife, and nifv. in this study an a. vinelandi ...19873477546
nitrogen fixation by azotobacter vinelandii in tungsten-containing medium.nitrogenase was isolated and purified from wild-type and a tungsten-resistant mutant (lm2) of azotobacter vinelandii strain op derepressed on medium containing 1-10 mm w. while the enzyme from the wild-type strain contained the polypeptides of the conventional enzyme, metal analysis of component 1 demonstrated the existence of one atom each of molybdenum and tungsten. furthermore, the esr spectrum of this protein contained three signals, two of which originated from s = 3/2 spin states. one of t ...19873479430
squid measurement of metalloprotein magnetization. new methods applied to the nitrogenase proteins.new techniques have been developed to exploit the sensitivity of a commercial squid susceptometer in the study of the magnetization of metalloproteins. previous studies have ignored both the slow relaxation (hours) of spin i = 1/2 nuclei and residual ferromagnetic impurities in sample holders. these potential sources of noise were at or below the sensitivity of previous instruments. with these noise sources under control, one can now decrease the protein concentration by a factor of ten. in addi ...19873480761
the nucleotide sequence of the sigma factor gene ntra (rpon) of azotobacter vinelandii: analysis of conserved sequences in ntra proteins.the nucleotide sequence of the azotobacter vinelandii ntra gene has been determined. it encodes a 56916 dalton acidic polypeptide (avntra) with substantial homology to ntra from klebsiella pneumoniae (kpntra) and rhizobium meliloti (rmntra). ntra has been shown to act as a novel rna polymerase sigma factor but the predicted sequence of avntra substantiates our previous analysis of kpntra in showing no substantial homology to other known sigma factors. alignment of the predicted amino acid sequen ...19873481423
[symmetry of multienzyme complexes].a model for studying the symmetry of stable states arising from polyenzymic complex conformations is proposed. a formal scheme of submolecular structure self-assembly, on which the model is based, enables it not only to limit the class of conformations but in some cases to determine the structure of a complex in an unambigous manner. the model is shown in its application to polyenzymic complexes of dehydrogenases of alpha-keto acids.19863512975
reversible inactivation of the o2-labile hydrogenases from azotobacter vinelandii and rhizobium japonicum.hydrogenases catalyze the reversible activation of dihydrogen. the hydrogenases from the aerobic, n2-fixing microorganisms azotobacter vinelandii and rhizobium japonicum are nickel- and iron-containing dimers that belong to the group of o2-labile enzymes. exposure of these hydrogenases to o2 results in an irreversible inactivation; therefore, these enzymes are purified anaerobically in a fully active state. we describe in this paper an electron acceptor-requiring and ph-dependent, reversible ina ...19863525552
structure predictions and surface charge of nitrogenase flavodoxins from klebsiella pneumoniae and azotobacter vinelandii.a first approximation to the tertiary structure of the nitrogenase flavodoxins of klebsiella pneumoniae and azotobacter vinelandii can be obtained by superimposing their amino acid sequences upon the crystallographically determined structure of the long-chain flavodoxin from anacystis nidulans. this procedure is validated by secondary structure predictions based on the sequence alone and by the distribution of polar and hydrophobic residues. it reveals, among other things, a distinctive distribu ...19863530760
electron transfer to nitrogenase. characterization of flavodoxin from azotobacter chroococcum and comparison of its redox potentials with those of flavodoxins from azotobacter vinelandii and klebsiella pneumoniae (niff-gene product).flavodoxin in the hydroquinone state acts as an electron donor to nitrogenase in several nitrogen-fixing organisms. the mid-point potentials for the oxidized-semiquinone and semiquinone-hydroquinone couples of flavodoxins isolated from facultative anaerobe klebsiella pneumoniae (niff-gene product, kpfld) and the obligate aerobe azotobacter chroococcum (acfld) were determined as a function of ph. the mid-point potentials of the semiquinone-hydroquinone couples of kpfld and acfld are essentially i ...19863541922
catalytic and allosteric mechanism of amp nucleosidase from primary, beta-secondary, and multiple heavy atom kinetic isotope effects.adenosine 5'-phosphate was synthesized with specific heavy atom substitutions to permit measurement of v/k kinetic isotope effects for the n-glycohydrolase activity of the allosteric amp nucleosidase and the acid-catalyzed solvolysis of these compounds. the effects of allosteric activation on the kinetic isotope effects together with the kinetic mechanism of amp nucleosidase [dewolf, w. e., jr., emig, f. a., & schramm, v. l. (1986) biochemistry 25, 4132-4140] indicate that the kinetic isotope ef ...19873552037
transition-state structures for n-glycoside hydrolysis of amp by acid and by amp nucleosidase in the presence and absence of allosteric activator.the mechanism of acid and enzymatic hydrolysis of the n-glycosidic bond of amp has been investigated by fitting experimentally observed kinetic isotope effects [parkin, d. w., & schramm, v. l. (1987) biochemistry (preceding paper in this issue)] to calculated kinetic isotope effects for proposed transition-state structures. the sensitivity of the transition-state calculations was tested by "arying the transition-state structure and comparing changes in the calculated kinetic isotope effects with ...19873552038
properties of allosteric nicotinamide mononucleotide glycohydrolase from azotobacter vinelandii: activation and inhibition.in order to clarify the regulation mechanism of nmn glycohydrolase, a number of purine and pyrimidine nucleotides were tested as activators for the enzyme. among naturally occurring nucleotides, pppgpp was shown to be the most potent activator (ka = 0.0087 mm). the effectiveness of these nucleotides estimated from vmax/ka was in the order: pppgpp greater than ppgpp greater than pppppg greater than ppppg greater than pgpp greater than gtp greater than or equal to 2'-gmp greater than or equal to g ...19873571198
protein synthesis during encystment of azotobacter vinelandii.proteins synthesized during the encystment of azotobacter vinelandii were radiolabeled with [35s]methionine and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. pulse labeling was used to demonstrate that early encystment-specific proteins were beginning to be synthesized at 2 h and reached peak levels about 12 h after initiation of encystment. one such protein was identified as a beta-ketoacyl acyl-carrier protein synthase. the concentration of early proteins began to decr ...19873654578
[effect of alkylresorcin on biological membranes during activation of lipid peroxidation].the effect of alkyl resorcin isolated from the cells of azotobacter chroococcum and of its structural analog devoid of the alkyl chain (resorcin) on liver microsomes and brain synaptosomes of the rat as well as on rabbit skeletal muscle sarcoplasmic reticulum fragments during activation of lipid peroxidation was studied. alkyl resorcin was shown to produce a much more potent antioxidant effect as compared with resorcin, since it inhibited lipid peroxidation in all the three types of membranes un ...19873663757
three-dimensional structure of the regular tetragonal surface layer of azotobacter vinelandii.fragments of the azotobacter vinelandii tetragonal surface (s) layer, free of outer membrane material, were obtained by treating whole cells with 100 microm edta. the three-dimensional structure of the s layer was reconstructed from tilted-view electron micrographs of the s-layer fragments, after computer-assisted image processing by correlation averaging. at a resolution of 1.7 nm, the s layer exhibited funnel-shaped subunits situated at one fourfold-symmetry axis and interconnected at the othe ...19873667523
the domain structure of the dihydrolipoyl transacetylase component of the pyruvate dehydrogenase complex from azotobacter vinelandii.limited proteolysis with trypsin has been used to study the domain structure of the dihydrolipoyltransacetylase (e2) component of the pyruvate dehydrogenase complex of azotobacter vinelandii. two stable end products were obtained and identified as the n-terminal lipoyl domain and the c-terminal catalytic domain. by performing proteolysis of e2, which was covalently attached via its lipoyl groups to an activated thiol-sepharose matrix, a separation was obtained between the catalytic domain and th ...19873691494
amp nucleosidase: kinetic mechanism and thermodynamics.the kinetic mechanism of amp nucleosidase (ec 3.2.2.4; amp + h2o----adenine + ribose 5-phosphate) from azotobacter vinelandii is rapid-equilibrium random by initial rate studies of the forward and reverse reactions in the presence of mgatp, the allosteric activator. inactivation-protection studies have established the binding of adenine to amp nucleosidase in the absence of ribose 5-phosphate. product inhibition by adenine suggests a dead-end complex of enzyme, amp, and adenine. methanol does no ...19863741845
alteration of glucose transport and diauxic growth in 5-thio-d-glucose-resistant mutants of azotobacter vinelandii.spontaneous mutants of azotobacter vinelandii defective for glucose utilization were selected as resistant to 5-thio-d-glucose. mutant strains am2, am38, and am39 exhibited longer generation times than the wild type when grown on glucose. mutant strain am2 also exhibited an altered km and vmax for glucose uptake. during acetate-glucose diauxie, glucose utilization in the 5-thio-d-glucose-resistant mutants was subject to severe inhibition by acetate. these mutants did not exhibit the normal gluco ...19863782023
a comparative carbon-13, nitrogen-15, and phosphorus-31 nuclear magnetic resonance study on the flavodoxins from clostridium mp, megasphaera elsdenii, and azotobacter vinelandii.the flavodoxins from megasphaera elsdenii, clostridium mp, and azotobacter vinelandii were studied by 13c, 15n, and 31p nmr techniques by using various selectivity enriched oxidized riboflavin 5'-phosphate (fmn) derivatives. it is shown that the pi electron distribution in protein-bound flavin differs from that of free flavin and depends also on the apoflavoprotein used. in the oxidized state clostridium mp and m. elsdenii flavodoxins are very similar with respect to specific hydrogen bond inter ...19863801391
structure of the azotobacter vinelandii surface layer.electron microscopy of the azotobacter vinelandii tetragonal surface array, negatively stained with ammonium molybdate in the presence of 1 mm calcium chloride, showed an apparent repeat frequency of 12 to 13 nm. image processing showed dominant tetrad units alternating with low-contrast cruciform structures formed at the junction of slender linkers extending from corner macromolecules of four adjoining dominant units. the actual unit cell showed p4 symmetry, and a = b = 18.4 nm. distilled water ...19873804978
the importance of quantitative mössbauer spectroscopy of mofe-protein from azotobacter vinelandii.the mössbauer spectra of mofe-protein of azotobacter vinelandii, as isolated under dithionite and taken at temperatures from 125 k to 175 k, are the sums of four resolved quadrupole doublets. our results indicate that the currently accepted interpretation of these doublets can be questioned. our data reduction method converts the mössbauer transmission spectra to source lineshape deconvolved absorption spectra linear in iron. we used these absorption spectra to determine the stoichiometry of the ...19853855748
the catalytic activity of nitrogenase in intact azotobacter vinelandii cells.the influence of the growth conditions on the concentration of nitrogenase and on the nitrogenase activity, was studied in intact azotobacter vinelandii cells. it was observed that whole cell nitrogenase activity could be enhanced in two ways. an increase of the growth rate of cells was accompanied by an increase in whole cell nitrogenase activity and by an increase in the concentration of nitrogenase in the cells. the molar ratio of fe protein:mofe protein was 1.47 +/- 0.17 and independent of t ...19853855749
inhibition of iron-molybdenum cofactor binding to component i of nitrogenase.tetrathiomolybdate inhibits iron-molybdenum cofactor (femo cofactor) binding to component i of nitrogenase. molybdenum-iron cluster (a subcomponent of femo cofactor) and tetrathiomolybdate inhibited femo cofactor activation of inactive nitrogenase component i in extracts of azotobacter vinelandii and klebsiella pneumoniae mutant strains defective in the biosynthesis of femo cofactor. addition of tetrathiotungstate, the tungsten analog of tetrathiomolybdate, to the mutant extracts had no signific ...19853856566
reversible and irreversible inactivation of cellular nitrogenase upon oxygen stress in azotobacter vinelandii growing in oxygen controlled continuous culture.azotobacter vinelandii growing in oxygen controlled chemostat culture was subjected to sudden increases of ambient oxygen concentrations (oxygen stress) after adaptation to different oxygen concentrations adjustable with air (100% air saturation corresponds to 225 +/- 14 microm o2). inactivations of cellular nitrogenase during stress (switch off) as well as after release of stress (switch on) were evaluated in vivo as depending on stress duration and stress height (delta po2). switch off was at ...19853857879
a modified flavodoxin with altered redox potentials is less efficient in electron transfer to nitrogenase.the flavodoxins of the azotobacter vinelandii wild-type and a mutant strain tzn 200 have been studied. although the primary structure of the two proteins is the same, the ability of the mutant flavodoxin to donate electrons to nitrogenase is reduced by 75%. one reason may be the raised mid-point potential of -435 mv for the semiquinone/hydroquinone couple in the mutant flavodoxin. the respective redox potential for the wild-type flavodoxin was found to be -480 mv. as shown by paper chromatograph ...19853857914
electron microscopy of the mo-fe-protein from azotobacter vinelandii nitrogenase.the quaternary structure of the mo-fe-protein from azotobacter vinelandii has been studied by electron microscopy. a model of the molecule of the mo-fe-protein has been proposed: two alpha subunits are displaced relative to two beta subunits along a twofold axis, so the molecule can be characterized by the point-group pseudosymmetry 222. computer averaging of the images showed that one of the projections of the molecule could be characterized by twofold rotational symmetry. micrographs of nitrog ...19853858099
complete nucleotide sequence of the azotobacter vinelandii nitrogenase structural gene cluster.dna fragments coding for the structural genes for azotobacter vinelandii nitrogenase have been isolated and sequenced. these genes, nifh, nifd and nifk, code for the iron (fe) protein and the alpha and beta subunits of the molybdenum-iron (mofe) protein, respectively. they are arranged in the order: promoter:nifh:nifd:nifk. there are 129 nucleotides separating nifh and nifd and 101 nucleotides separating nifd and nifk. the amino acid (aa) sequences deduced from the nucleotide sequences are discu ...19853863780
diauxic growth in azotobacter vinelandii.azotobacter vinelandii exhibited diauxie when grown in a medium containing both acetate and glucose as carbon sources. acetate was used as the primary carbon source during the acetate-glucose diauxie. uptake of acetate was constitutively expressed during both diauxic phases of growth. induction of the glucose uptake system was inhibited in the presence of acetate. acetate was also the preferred growth substrate for a. vinelandii grown in a medium containing either fructose, maltose, xylitol, or ...19853863813
purification and properties of the nitrogenase of azospirillum amazonense.the nitrogenase of the free-living, microaerobic, n2-fixing bacterium azospirillum amazonense (strain y1) was purified by chromatography on deae-52 cellulose, by heat treatment, and by preparative polyacrylamide gel electrophoresis. the specific nitrogenase activities were 2,400 nmol of c2h4 formed per min per mg of protein for dinitrogenase (mofe protein) and 1,800 nmol of c2h4 formed per min per mg of protein for dinitrogenase reductase (fe protein). the mofe protein was composed of a minimum ...19853864779
properties of the mgatp and mgadp binding sites on the fe protein of nitrogenase from azotobacter vinelandii.flow dialysis was used to study the binding of mgatp and mgadp to the nitrogenase proteins of azotobacter vinelandii. both reduced and oxidized av2 bind two molecules of mgadp, with the following dissociation constants: reduced av2, k1 = 0.091 +/- 0.021 mm and k2 = 0.044 +/- 0.009 mm; oxidized av2, k1 = 0.024 +/- 0.015 mm and k2 = 0.039 +/- 0.022 mm. binding of mgadp to reduced av2 shows positive co-operativity. oxidized av2 binds two molecules of mgatp with dissociation constants k1 = 0.049 +/- ...19853873334
molecular cloning of nif dna from azotobacter vinelandii.two clones which contained nif dna were isolated from a clone bank of total ecori-digested azotobacter vinelandii dna. the clones carrying the recombinant plasmids were identified by use of the 32p-labeled 6.2-kilobase (kb) nif insert from psa30 (which contains the klebsiella pneumoniae nifk, nifd, and nifh genes) as a hybridization probe. hybridization analysis with fragments derived from the nif insert of psa30 showed that the 2.6-kb insert from one of the plasmids (plb1) contains nifk whereas ...19853884589
hybrid pyruvate dehydrogenase complexes reconstituted from components of the complexes from escherichia coli and azotobacter vinelandii.the pyruvate dehydrogenase complex of escherichia coli was isolated in a simple three-step procedure. its chain stoichiometry, determined by trinitrobenzoate modification was found to be 1.4 e1:1 e2:0.6 e3. it was reproducible within 10% from preparation to preparation. the e. coli complex was resolved by chromatography on activated thiol sepharose. reconstitution of activity yielded a stoichiometry of 1.0 e1:1 e2:0.5 e3. the optimum binding stoichiometry of e1e2 and e2e3 subcomplexes was determ ...19853899642
the base sequence of the niff gene of klebsiella pneumoniae and homology of the predicted amino acid sequence of its protein product to other flavodoxins.the nucleotide sequence of a 629 base-pair segment of dna spanning the niff gene of klebsiella pneumoniae is presented. the structural gene comprises 531 base-pairs (175 codons, excluding the translational initiator and terminator) encoding an acidic polypeptide of 18950 da. the niff product thus belongs to the long-chain class of flavodoxins. it shows some sequence homology to the short-chain flavodoxins from desulfovibrio vulgaris, clostridium mp and megasphaera elsdenii, and much stronger hom ...19853911951
covalent modification of the iron protein of nitrogenase from rhodospirillum rubrum by adenosine diphosphoribosylation of a specific arginine residue.nitrogenase in rhodospirillum rubrum is inactivated in vivo by the covalent modification of the fe protein with a nucleotide. the preparation of two modified peptides derived from proteolytic digestion of the inactive fe protein is described. the modifying group is shown to be adenosine diphosphoribose, linked through the terminal ribose to a guanidino nitrogen of arginine. the structural features were established by using proton and phosphorus nmr, positive- and negative-ion fast atom bombardme ...19853923473
new perspectives on bacterial ferredoxin evolution.recent evidence indicates that a gene transposition event occurred during the evolution of the bacterial ferredoxins subsequent to the ancestral intrasequence gene duplication. in light of this new information, the relationships among the bacterial ferredoxins were reexamined and an evolutionary tree consistent with this new understanding was derived. the bacterial ferredoxins can be divided into several groups based on their sequence properties; these include the clostridial-type ferredoxins, t ...19853932661
biochemical and biophysical properties of cytochrome o of azotobacter vinelandii.cytochrome o, solubilized from the membrane of azotobacter vinelandii, has been purified to homogeneity as judged by ultracentrifugation and polyacrylamide gel electrophoresis. the detergent-containing cytochrome o is composed of one polypeptide chain with a molecular weight of 28 000-29 000, associated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. the enzyme exists as a dimer by gel filtration analysis. the amino analysis which reveals the majority of residues ...19863947619
characterization of three different flavodoxins from azotobacter vinelandii.the flavodoxins from azotobacter vinelandii cells grown n2-fixing and from cells grown on nh4oac have been purified and characterized. the purified flavodoxins from these cells are a mixture of three different flavodoxins (fld i, ii, iii) with different primary structures. the three proteins were separated by fast protein liquid chromatography; fld i eluted at 0.38 m kcl, fld ii at 0.43 m kcl and fld iii at 0.45 m kcl. the most striking difference between the three flavodoxins was the midpoint p ...19863948879
iron-sulfur cluster in aconitase. crystallographic evidence for a three-iron center.native x-ray diffraction data from single crystals of inactive aconitase from pig heart (mr 80,000) have been collected on oscillation films to 2.7 a. analysis shows that significant measurements of the anomalous scattering signal from the fe-s cluster in the enzyme are available in the film data. the 5.0-a resolution anomalous difference patterson function contains vectors for one fe-s cluster (one aconitase molecule) per asymmetric unit in space group p2(1)2(1)2 with a = 173.6, b = 72.0, and c ...19853972791
transformation of azotobacter vinelandii with plasmid dna.azotobacter vinelandii cells can be transformed at high frequencies with the broad-host-range plasmids prk2501, rsf1010, and pgss15, using a modification of the procedure developed by page and von tigerstrom (j. bacteriol. 139:1058-1061, 1979) for chromosomal dna-mediated transformation. the frequency of transformation per microgram of plasmid dna per viable cell with prk2501 and pgss15 was about 5 x 10(-2) and 2 x 10(-2), respectively. with rsf1010, transformation frequencies ranged from 3 x 10 ...19853980437
evidence for two nonidentical subunits of bacterioferritin from azotobacter vinelandii.the bacterioferritin from azotobacter vinelandii exhibits properties which in ferritins from other sources are attributed to the heteropolymeric nature of the holoprotein. the native bacterioferritin displayed multiple bands on isoelectric focusing gels. on discontinuous sodium dodecyl sulfate-polyacrylamide gels, there were two subunit polypeptides of approximate mr 21,000 and 23,000. these molecular weights were corroborated by gel filtration experiments. peptide maps produced by partial tryps ...19853988707
lesions in citrate synthase that affect aerobic nitrogen fixation by azotobacter chroococcum.a class of azotobacter chroococcum mutants induced by tn1 that were defective in normal aerobic nitrogen fixation when grown on sugars (fos-) were corrected by provision of alpha-ketoglutarate or glutamate. in a representative mutant, fos252, rates of evolution of 14co2 from [14c]acetate or [14c]glucose were 5% of the parental values, although uptake and incorporation were normal for both substrates. the results suggest that a lesion affects the entry of substrates into the tricarboxylic acid cy ...19853988712
presence of 2-methylthioribosyl-trans-zeatin in azotobacter vinelandii trna.hydroxylated cytokinin, 2-methylthio-n6-(4-hydroxy-3-methylbut-2-enyl) adenosine, was found in the trna of azotobacter vinelandii. this cytokinin had the trans configuration, unlike the cis configuration reported for that from other bacteria. culture-condition-dependent changes in the content of this thiocytokinin and a few other thionucleosides in the trna of this bacterium have been observed.19853988713
chlorpromazine inhibition of electron transport in azotobacter vinelandii membranes.chlorpromazine was a potent inhibitor of o2-dependent malate oxidation, but not of h2 oxidation in azotobacter vinelandii membranes. however, chlorpromazine did not significantly affect the activity of malate reductase or the reduction of cytochromes c and d. in the presence of chlorpromazine, cytochrome o failed to form a complex with co. the site of action of chlorpromazine seems to be in the cytochromes c to cytochrome o branch, the pathway utilized by malate, succinate and nadh, but not by h ...19853995019
molecular and immunological comparison of membrane-bound, h2-oxidizing hydrogenases of bradyrhizobium japonicum, alcaligenes eutrophus, alcaligenes latus, and azotobacter vinelandii.the membrane-bound hydrogenases of bradyrhizobium japonicum, alcaligenes eutrophus, alcaligenes latus, and azotobacter vinelandii were purified extensively and compared. sodium dodecyl sulfate-polyacrylamide gel electrophoresis of each hydrogenase revealed two prominent protein bands, one near 60 kilodaltons and the other near 30 kilodaltons. the migration distances during nondenaturing polyacrylamide gel electrophoresis were similar for all except a. vinelandii hydrogenase, which migrated furth ...19854008438
h2-dependent mixotrophic growth of n2-fixing azotobacter vinelandii.azotobacter vinelandii can grow with a variety of organic carbon sources and fix n2 without the need for added h2. however, due to an active h2-oxidizing system, h2-dependent mixotrophic growth in an n-free medium was demonstrated when mannose was provided as the carbon source. there was no appreciable growth with either h2 or mannose alone. both the growth rate and the cell yield were dependent on the concentrations of both substrates, h2 and mannose. cultures growing mixotrophically with h2 an ...19854019408
uv-repair and mutagenesis in azotobacter vinelandii. ii. repair and mutagenesis.more numbers of mutants were isolated when uv-irradiated cells of azotobacter vinelandii op were treated with caffeine for a limited period of time after uv-irradiation. this is encouraging, considering the difficulty in isolating azotobacter mutants. post-irradiation treatment with acriflavine, however, yielded comparatively lesser number of mutants.19854036386
regions of broad-host-range plasmid rk2 involved in replication and stable maintenance in nine species of gram-negative bacteria.the replication and maintenance properties of the broad-host-range plasmid rk2 and its derivatives were examined in nine gram-negative bacterial species. two regions of rk2, the origin of replication (oriv) and a segment that encodes for a replication protein (trfa delta kild, designated trfa*), are sufficient for replication in all nine species tested. however, stable maintenance of this minimal replicon (less than 0.3% loss per generation under nonselection conditions) is observed only in esch ...19854044529
nh4+ derepression of azide resistant mutant of azotobacter chroococcum.five azide resistant mutants of azotobacter chroococcum were isolated after mnng mutagenesis. these mutants varied in their ability to detoxify azide in the presence of nh4+ and this ability has been found to be directly related to nh4+ derepression.19854090767
[the effect of various gamma radiation doses on the growth of azotobacter chroococcum beij]. 19684098154
ultrastructure of azotobacter vinelandii.vegetative cells and cysts of azotobacter vinelandii 12837 were prepared for electron microscopy by several methods assumed to preserve structural details destroyed by techniques previously reported in the literature. examination of large numbers of cells and cysts by these methods revealed four structural details not reported previously: intine fibrils, intine vesicles, intine membrane, and microtubules. the intine fibrils form a network in the gel-like homogeneous matrix of the cc2 layer. inti ...19704099100
effect of dieldrin and lindane on soil microorganisms. 19704100539
giant cysts and cysts with multiple central bodies in azotobacter vinelandii.cyst germination in azotobacter vinelandii atcc 12837 was studied by using phase contrast and electron microscopy. germination in this organism was accompanied by the formation of large cyst forms of two different types: giant cysts and cysts containing multiple central bodies. previously, these two types have been reported only when yeast extract was added to the encystment medium. in this study, we observed giant cysts and cysts with multiple central bodies in nitrogen-free liquid medium. the ...19714105031
microorganisms in unamended soil as observed by various forms of microscopy and staining.a light-diffraction microscope was modified to allow sequential viewing of the microorganisms in a soil smear by transmitted, reflected, and reflected-polarized incandescent light and by reflected ultraviolet light. observations were also made by conventional incandescent and ultraviolet transmitted-light microscopy. all results for the various forms of bright-field microscopy with stained and unstained soils were in agreement, but they differed from the results obtained for two types of ultravi ...19714105130
determination of isocitrate lyase activity in polyacrylamide gels. 19724115982
improved staining of extracellular polymer for electron microscopy: examination of azotobacter, zoogloea, leuconostoc, and bacillus.phase contrast, ultraviolet microscopy, and freeze-etching were used to determine the amount of exocellular polymer surrounding unfixed cells of four genera of bacteria: azotobacter vinelandii, zoogloea ramigera, leuconostoc mesenteroides, and an acid-tolerant, floc-forming bacillus species. thin-sectional electron microscopy was employed to measure the effectiveness of a modified ruthenium red staining method. the results obtained with this modification of ruthenium red staining technique were ...19724116892
internal membrane control in azotobacter vinelandii.azotobacter vinelandii was grown on n(2), nh(4) (+), or no(3) (-), and an internal membrane network was observed by electron microscopy of thin sections of cells. cells obtained in early exponential growth contained less internal membrane than did cells from cultures in late exponential growth. it seems likely that o(2) has a role in regulating the amount of internal membrane structure.19734123239
properties of azotobacter phage a14 and its dna. 19734127969
cooperative interactions in enzymes: the binding of 1, n6-etheno-atp to aztobacter vinelandii nitrogenase. 19734133565
nitrogenase. 19744134899
critical-point drying: rapid method for the determination of bacterial extracellular polymer and surface structures.the relative amount of extracellular polymer which remains about azotobacter vinelandii, zoogloea ramigera, klebsiella pneumoniae, and diplococcus pneumoniae after critical-point drying was studied by electron microscopy. the results obtained with this technique are compared to those obtained with methods that illustrate extracellular polymer, such as freeze-etching and ruthenium red staining. comparative results indicate critical-point drying to be a rapid, reliable method for the determination ...19744136617
detection of nitrogenase components and other nonheme iron proteins in polyacrylamide gels. 19744136629
isocitrate dehydrogenase from azotobacter vinelandii. order of substrate addition and product release. 19724144061
purification and properties of nicotinamide mononucleotide amidohydrolase from azotobacter vinelandii. 19734144084
purification and characterization of ferredoxin-nicotinamide adenine dinucleotide phosphate reductase from a nitrogen-fixing bacterium.evidence suggesting that bacillus polymyxa has an active ferredoxin-nadp(+) reductase (ec 1.6.99.4) was obtained when nadph was found to provide reducing power for the nitrogenase of this organism; direct evidence was provided when it was shown that b. polymyxa extracts could substitute for the native ferredoxin-nadp(+) reductase in the photochemical reduction of nadp(+) by blue-green algal particles. the ferredoxin-nadp(+) reductase was purified about 80-fold by a combination of high-speed cent ...19734147648
reduced nicotinamide-adenine dinucleotide-nitrite reductase from azotobacter chroococcum.1. the assimilatory nitrite reductase of the n(2)-fixing bacterium azotobacter chroococcum was prepared in a soluble form from cells grown aerobically with nitrate as the nitrogen source, and some of its properties have been studied. 2. the enzyme is a fad-dependent metalloprotein (mol.wt. about 67000), which stoicheiometrically catalyses the direct reduction of nitrite to nh(3) with nadh as the electron donor. 3. nadh-nitrite reductase can exist in two either active or inactive interconvertible ...19734147887
multiple sites for coupling of glucose transport to the respiratory chain of membrane vesicles from azotobacter vinelandii. 19734148099
triphosphopyridine nucleotide specific isocitrate dehydrogenase from azotobacter vinelandii. alkylation of a specific methionine residue and amino acid sequence of the peptide containing this residue. 19744149369
studies on a non-pyridine nucleotide dependent, membrane-bound l-(+)-glutamate oxidoreductase in azotobacter vinelandii. 19734149668
[existence of a low-molecular factor, common to different molybdenum-containing enzymes]. 19744152421
electron transport carriers involved in nitrogen fixation by the coliform, klebsiella pneumoniae. 19744153345
regulation of dinitrogen fixation in intact azotobacter vinelandii. 19744153464
the pathways of nitrogen fixation. 19724146649
influence of root extracts and root exudates on respiratory activity of azotobacter. 19664161876
the occurrence of azotobacter spp. in soils from monocultures of rye and potatoes. 19684178169
epr studies on phosphorylating particles from azotobacter vinelandii. 19734146343
[application of immunofluorescence technic to the study of azotobacter of the soil]. 19704192933
[effect of 3-amino-1,2,4-triazole (amitrol) on the ultrastructure of azotobacter]. 19704195297
permeability of azotobacter vinelandii to cations and anions. 19734198137
evolution of asymbiotic nitrogen fixation. 19734198818
differential counting in mixed cultures with coulter counters.a critical comparison of coulter, viable, and microscope counts for several mixed cultures of microorganisms has been made. this investigation shows that coulter counting can provide reliable estimates of microbial numbers in mixed cultures. precautions and limitations of coulter counting in mixed cultures are discussed.19734199341
comparative biology of prokaryotic resting cells. 19734199775
the respiratory chain of azotobacter vinelandii. i. spectral properites of cytochrome d. 19734200350
production and characterization of the slime polysaccharide of pseudomonas aeruginosa.the slime polysaccharides produced by pseudomonas aeruginosa isolated from a variety of human infections were investigated. slime production in culture seemed optimal when adequate amounts of carbohydrate were present and under conditions of either high osmotic pressure or inadequate protein supply. the polysaccharides produced by the organisms were similar to each other, to the slime of azotobacter vinelandii, and to seaweed alginic acids. they were composed of beta-1,4-linked d-mannuronic acid ...19734200860
comparative aspects of morphogenesis in three prokaryotic genera. 19734201689
microbial food chains and food webs. 19734202222
azotobacter vineland ii rna polymerase. xi. effect of transcription on rifampicin binding. 19734203341
mutant of azotobacter vinelandii that hyperproduces nitrogenase component ii.a mutant strain of azotobacter vinelandii that is unable to fix n(2) produces high levels of nitrogenase component ii. activities of revertants from this mutant strain indicate that a single genetic lesion is responsible for both hyperproduction of component ii and the inability to produce component i.19744204445
steady-state enzyme kinetics with high-affinity substrates or inhibitors. a statistical treatment of dose-response curves.a statistical treatment of steady-state enzyme kinetic measurements is described that allows for depletion of free substrate or free inhibitor concentrations owing to significant binding to the enzyme. v(max.), k(m) or k(i), enzyme concentration, the concentration of substrate or inhibitor required for a half-maximal effect and standard errors of these parameters can be calculated from dose-response measurements; the concentration of each component of the system may be estimated also. the statis ...19734204669
[molecular nitrogen fixation by microorganisms (review of work carried out in the ussr during the period 1966-1972)]. 19734205186
[effect of soluble molybdenum level in the sail on the microflora of the nitrogen cycle. agronomic applications]. 19734206011
interaction between azotobacter chroococcum, bacillus megaterium var. phosphaticum and rhizobium sp. 19734207213
[characteristics of the development of oligonitrophils in assimilating bound forms of nitrogen]. 19734208365
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