Publications

studies of photochemical action spectra on n,n,n',n'-tetramethyl-p-phenylenediamine-oxidase-negative mutants of azotobacter vinelandii.		1980	6245877
preparation of alpha-nadp+.		1980	6246394
nitrogenase xii. mössbauer studies of the mofe protein from clostridium pasteurianum w5.	we have studied the molybdenum-protein (mofe protein) from clostridium pasteurianum with mössbauer spectroscopy in the temperature range from 1.5 to 200 k in magnetic fields up to 55 kg. except for some small differences in the hyperfine parameters the results for the c. pasteurianum protein are essentially the same as those published previously for the protein from azotobacter vinelandii, i.e. (30 +/- 2) fe atoms partition into two identical cofactor centers m (each center most likely containin ...	1980	6246963
interaction of mn2+ and mnatp2- with the allosteric sites of amp nucleosidase.		1980	6247346
evidence of substantial separation of the catalytic and allosteric sites of amp nucleosidase.		1980	6251048
[localization of oxidative enzymes of bacteria by means of electron microscopic cytochemistry].		1980	6251675
redox and spectroscopic properties of oxidized mofe protein from azotobacter vinelandii.	the mofe protein from azotobacter vinelandii undergoes a six-electron oxidation by various organic dye oxidants with full retention of initial activity. reduction of the oxidized protein by s2o42- and by controlled potential electrolysis indicates the presence of two reduction regions at -290 and -480 mv, each requiring three electrons for complete reaction. control of the oxidation conditions provides a means for preparing two distinct mofe protein species selectively oxidized by three electron ...	1980	6252962
respiratory properties of cytochrome-c-deficient mutants of azotobacter vinelandii.	cytochrome-c-deficient mutants of azotobacter vinelandii have been isolated following mutagenesis with n-methyl-n'-nitro-n-nitrosoguanidine. these mutants grow well under nitrogen-fixing conditions and studies of the physiology and energy conservation efficiency show no apparent differences from those of the parent strain. under oxygen-limited growth conditions, the growth rate of the cytochrome-c-deficient mutant was slightly slower (approx. 15%) than that of the parent strain. cytochromes of t ...	1980	6254768
iron-sulfur proteins: spin-coupling model for three-iron clusters.	recent mössbauer and epr studies of two ferredoxins and of aconitase have given evidence for a three-iron cluster, probably of a [3fe-3s] type. the studies of the oxidized epr-active centers have shown that the three iron sites are characterized by significantly different magnetic hyperfine coupling constants. for the ferredoxin from azotobacter vinelandii, for instance, we have observed a1 = -41 mhz, a2 = +18 mhz, and [a3] = 5 mhz. we demonstrate here that the magnetic properties of the cluster ...	1980	6256746
nucleotide sequence of the gene coding for the nitrogenase iron protein from klebsiella pneumoniae.	we report the complete dna sequence of the klebsiella pneumoniae nifh gene, the gene which codes for component 2 (fe protein or nitrogenase reductase) of the nitrogenase enzyme complex. the amino acid sequence of the k. pneumoniae nitrogenase fe protein is deduced from the dna sequence. the k. pneumoniae fe protein contains 292 amino acids, has a mr = 31,753, and contains 9 cysteine residues. we compare the amino acid sequence of the k. pneumoniae protein with available amino acid sequence data ...	1981	6259144
adenine nucleotide metabolism in azotobacter vinelandii. two metabolic pathways of amp degradation.	amp-degrading pathways in azotobacter vinelandii cells were investigated. amp nucleosidase (ec 3.2.2.4) was rapidly synthesized and reached a maximum at 24 h, while the activity of 5'-nucleotidase (ec 3.1.3.5) specific for amp, which was negligible during the logarithmic phase of the growth, first appeared in 24 h-cultures, and reached a maximum after complete exhaustion of sucrose from the growth medium (70 h). cell-free extracts of a. vinelandii of 48 h-cultures hydrolyzed amp to ribose 5-phos ...	1980	6260050
effect of ligands on cytochrome d from azotobacter vinelandii.	spectra of oxidized and reduced cytochrome d in particles of a. vinelandii were studied in the presence of the ligands co, azide, and nh2oh under oxidizing, reducing, and turnover conditions. under oxidizing conditions, spectral changes were observed on oxidized cytochrome d (absorption maximum at 648 nm) in the presence of co and nh2oh showing a shift of the maximum to shorter wavelengths (639 and 645 nm, respectively) and a broadening of the half-band width. under reducing conditions, spectral ...	1980	6260768
oxidation-reduction titration of cytochrome components in the electron transport chaim of azotobacter vinelandii.	the multiple cytochrome components in the electron transport particle of azotobacter vinelandii were resolved and their oxidation-reduction midpoint potentials were determined by a simultaneous potentiometric and absorption measurements under anaerobic condition with or without co. the midpoints of the individual cytochrome component corresponding to the membrane-bound types were also determined in the solubilized fractions prepared by a differential detergent solubilization of the membrane part ...	1981	6263427
identification of neutral and anionic 8 alpha-substituted flavin semiquinones in flavoproteins by electron spin resonance spectroscopy.		1981	6266343
isolation of a molybdenum--iron cluster from nitrogenase.	a molybdenum-iron cluster (mo-fe cluster) containing 6 fe atoms per mo was isolated by methyl ethyl ketone extraction of component i of nitrogenase from azotobacter vinelandii. the cluster has no epr signal in the g = 4 region but has an intense signal at g = 2.05 and 2.01. after the cluster was transferred from methyl ethyl ketone to n-methylformamide, the signal in the g = 2 region disappeared and a signal similar to that found with fe-mo cofactor appeared. the mo-fe cluster is the epr-active ...	1981	6267591
isolation and purification of the cytochrome oxidase of azotobacter vinelandii.	a membrane-bound cytochrome oxidase for azobacter vinelandii was purified 20-fold using a detergent-solubilization procedure. activity was monitored using as ascorbate-tmpd oxidation assay. the oxidase was 'solubilized' from a sonic-type electron-transport particle (r3 fraction) using triton x-100 and deoxycholate. low detergent concentrations first solubilized the flavoprotein oxidoreductases, then higher concentrations of triton x-100 and kcl solubilized the oxidase, which was precipitated at ...	1981	6271199
an alternative pathway for the biosynthesis of isoprenoid compounds in bacteria.	the pattern of incorporation of radioactivity from [1-14c]acetate and [2-14c]acetate into the polyprenyl side-chain of ubiquinones in bacteria (azotobacter vinelandii, pseudomonas sesami, escherichia coli and rhodopseudomonas capsulata) was studied. for this purpose, a new degradation method involving a modified barbier-wieland reaction of laevulinic acid was developed, and used along with the iodoform reaction. both c-1 and c-2 of acetate were incorporated exclusively into c-2 of laevulinic aci ...	1981	6274317
stoichiometry and spectral properties of the mofe cofactor and noncofactor redox centers in the mofe protein of nitrogenase from azotobacter vinelandii.	reductive epr and optical titrations of oxidized mofe protein using reduced methyl viologen as reductant were used to quantitate the stoichiometry of the various spectroscopically and electrochemically distinct redox centers in the oxidized mofe protein. three centers were found to correlate with the epr signal development (mofe cofactor centers), and three centers were found to be independent of the epr signal (p clusters) but to demonstrate distinct optical and kinetic properties. oxidative ep ...	1981	6274395
the effect of the redox potential on the activity of the nitrogenase and on the fe-protein of azotobacter vinelandii.		1982	6276174
expression of an alternative nitrogen fixation system in azotobacter vinelandii.	nitrogenase activities were determined from maximum acetylene reduction rates for mutant strains of azotobacter vinelandii which are unable to fix n2 in the presence of molybdenum (nif-) but undergo phenotypic reversal to nif+ under conditions of mo deficiency. the system responsible for n2 fixation under these conditions is thought to be an alternative n2 fixation system (bishop et al., proc. natl. acad. sci. u.s.a. 77:7342-7346, 1980). phenotypic reversal of nif- strains to nif+ strains was al ...	1982	6281240
iron-molybdenum cofactor from nitrogenase. modified extraction methods as probes for composition.	five modifications of the preparative procedure for isolating iron-molybdenum cofactor (femoco) from the molybdenum-iron (mofe) protein of azotobacter vinelandii nitrogenase have been developed. this variety of isolation methods has established that no single component of the original isolation protocol, i.e. tris, cl-, citrate, hpo4(2-), n,n-dimethylformamide, and n-methylformamide, is essential for the effective isolation and/or structural stability of femoco, although any of them may act as l ...	1982	6282869
on the operon structure of the nitrogenase genes of rhizobium leguminosarum and azotobacter vinelandii.	the transcription of the nitrogenase genes in rhizobium leguminosarum was studied by analysing total cellular rna from bacteroids for the presence of nitrogenase messenger rna. the rna was separated by agarose gel electrophoresis and blotted onto nitrocellulose filters. messenger rna for nitrogenase was detected by hybridization with probes derived from plasmid psa30, a recombinant plasmid carrying the nitrogenase genes of klebsiella pneumoniae. in the same way nitrogenase mrna was detected in r ...	1982	6289264
ferredoxin from methanosarcina barkeri: evidence for the presence of a three-iron center.	methanosarcina barkeri ferredoxin was purified and characterized by electron paramagnetic resonance (epr) and mössbauer spectroscopy. the purification procedure included chromatographic steps on deae-cellulose and gel filtration. the isolated protein is unstable under aerobic conditions. the ferredoxin exhibits charge transfer bands at 283 nm and 405 nm with an absorption ratio a405/a283 = 0.73. its molecular weight has been estimated to be 20000-22000 by gel filtration chromatography. the nativ ...	1982	6290216
membrane-bound cytochromes c of pseudomonas aeruginosa grown aerobically. purification and characterization of cytochromes c-551 and c-555.	membrane-bound cytochromes c of pseudomonas aeruginosa grown aerobically were investigated. by detecting polypeptides with heme-catalyzing peroxidase activity on a sodium dodecyl sulfate polyacrylamide gel, four major (band i, 33,000 daltons; ii, 25,000; iii, 20,000; iv, 16,000) and one minor (v, 11,500) hemoproteins were found in the membrane fraction, while one hemoprotein (vi, 8,200) was detected in a small amount in the cytosol fraction. all these hemoproteins (bands i to vi) appeared to be ...	1982	6296063
activation of nif gene expression in azotobacter by the nifa gene product of klebsiella pneumoniae.	structural similarity of nitrogenase, the enzyme responsible for biological nitrogen fixation, from various diazotrophic bacteria has been shown by intergeneric biochemical complementation of component proteins in vitro, dna and protein sequence analysis, and dna hybridization between nif (nitrogen fixation) structural genes from klebsiella pneumoniae and genomic sequences from other nitrogen-fixing bacteria. despite nitrogenase homologies, little is known about similarities among nif regulatory ...	1983	6298627
iron-sulfur stoichiometry and structure of iron-sulfur clusters in three-iron proteins: evidence for [3fe-4s] clusters.	beef heart aconitase contains 3fe clusters in its inactive and 4fe clusters in its active form. the fully active form can be restored from the inactive one by insertion of fe(2+), whereas s(2-) is not required. chemical analyses for iron and labile sulfide yield fe/s(2-) ratios of 0.66-0.74 for the inactive and 0.90-1.03 for the active form. sulfane sulfur (s(0)) was not detected. we propose on the basis of these data that the inactive form may arise from the active one by loss of one iron only ...	1983	6300839
the 650 and chromophore in escherichia coli is an 'oxy-' or oxygenated compound, not the oxidized form of cytochrome oxidase d: an hypothesis.	the form of cytochrome d in escherichia coli and azotobacter vinelandii that shows an absorption maximum at 648 to 652 nm ('cytochrome d650') is generally regarded as the oxidized form of this terminal oxidase. membranes from e. coli grown under oxygen-limited conditions, when treated with ferricyanide, do not reveal cytochrome d650, whereas a sharp symmetrical band at 652 nm results from the reaction of the reduced enzyme with o2 at either room temperature or after flash photolysis of the co-li ...	1983	6311941
construction of a gene library from the nitrogen-fixing aerobe azotobacter vinelandii.	we have cloned the dna of azotobacter vinelandii in the cosmid phc79. recombinant cosmids that can transform escherichia coli leub- to a leu+ phenotype, as well as those having sequence homology to the nitrogenase structural genes of klebsiella pneumoniae have been selected from this library.	1983	6319242
h2-uptake activity of the mofe protein component of azotobacter vinelandii nitrogenase.	the mofe protein from azotobacter vinelandii catalyzes the reduction of methylene blue and other oxidants by h2 under anaerobic conditions. h2 uptake followed manometrically or by 3h2 transfer from the gas to aqueous phase occurs concomitantly with methylene blue disappearance monitored optically or coulometrically. the stoichiometry was found to be 1:1 methylene blue/h2. mofe protein oxidized by transfer of approximately 4 e- seems to be the redox state of the protein most active in the catalyt ...	1984	6320185
survey, purification, and properties of sugar phosphate phosphohydrolase among microorganisms.	sugar phosphate phosphohydrolase was purified approximately 500- to 600-fold to apparent homogeneity from escherichia coli b, escherichia coli c, escherichia coli var. communior, escherichia acidilactici, enterobacter aerogenes, neisseria meningitidis, and saccharomyces cereviseae. the molecular weights of the enzyme as estimated by gel filtration ranged from 97 x 10(3) to 101 x 10(3). the enzyme was composed of two subunits with the same molecular weight which ranged from 50 x 10(3) to 52 x 10( ...	1983	6322944
spectroscopic studies of ferricyanide oxidation of azotobacter vinelandii ferredoxin i.	the fe(cn)3-(6) oxidation of the crystallographically characterized [[3fe-3s], [4fe-4s]] ferredoxin i of azotobacter vinelandii has been studied using absorption, circular dichroism, magnetic circular dichroism, and epr spectroscopies. a paramagnetic intermediate is observed en route to fe-s cluster-free apoprotein, possessing an anisotropic g approximately equal to 2 epr signal, surviving to temperatures greater than 77 k. this species is shown to result from 3-electron oxidation of the [4fe-4s ...	1984	6326091
reactions with the oxidized iron protein of azotobacter vinelandii nitrogenase: formation of a 2fe center.	the fe-s center of oxidized fe protein from azotobacter vinelandii nitrogenase is decomposed by alpha,alpha'-dipyridyl in a biphasic process. in the presence of mgatp, 2 fe are immediately removed by chelation while the additional irons are removed only after several hours. a slower biphasic fe release also was observed in the presence of chelator alone. mgadp prevented the fe release by chelator. an intermediate in the reaction was isolated containing 2 fe. the visible spectrum of the intermedi ...	1984	6329264
characterization of three iron ferredoxins by microwave power saturation.	we have measured the electronic spin lattice relaxation time t1 in the temperature range 4 k-10 k, by microwave power saturation on the 3fe ferredoxins from desulfovibrio gigas and azotobacter vinelandii. the comparison with the results previously obtained on other iron sulfur proteins emphasizes the particularly fast relaxing properties of the e.p.r. signal in 3fe ferredoxins. these results support the models of the active site which predict very low lying excited levels.	1984	6329322
potentiometric titrations and oxidation--reduction potentials of several iron superoxide dismutases.		1983	6340720
three-iron clusters in iron-sulfur proteins.	contents. 1. introduction and history. 2. characteristic spectroscopic features of 3fe clusters. 1. general considerations. 2. mössbauer spectroscopy. 3. magnetic circular dichroism (mcd) spectroscopy. 4. electron paramagnetic resonance (epr) spectroscopy. 5. resonance raman (rr) spectroscopy. 6. extended x-ray fine-structure (exafs) spectroscopy. 3. results of x-ray diffraction studies. 4. proteins containing or showing features characteristic of 3fe clusters 1. overview. 2. ferredoxin i of azo ...	1983	6342537
nitro analogs of substrates for adenylosuccinate synthetase and adenylosuccinate lyase.	the reactivities of the nitro analogs of the substrates of adenylosuccinate synthetase and adenylosuccinate lyase, the enzymes which catalyze the penultimate and last step, respectively, in the pathway for amp biosynthesis have been examined. alanine-3-nitronate, an aspartate analog, was a substrate for the synthetase from azotobacter vinelandii, having a kcat/km which was approximately 30% that for aspartate. the product of this reaction was n6-(l-1-carboxy-2-nitroethyl)-amp. of nine other subs ...	1983	6351751
electron transport to nitrogenase. purification and characterization of pyruvate:flavodoxin oxidoreductase. the nifj gene product.	pyruvate:flavodoxin oxidoreductase, the nifj gene product of klebsiella pneumoniae, was purified to homogeneity. pyruvate:flavodoxin oxidoreductase, flavodoxin, and nitrogenase components i and ii are the only proteins required for pyruvate-coupled nitrogenase activity. the physiological source of electrons to nitrogenase in k. pneumoniae is pyruvate. flavodoxin from azotobacter vinelandii was only one-third as effective as k. pneumoniae flavodoxin in transferring electrons from pyruvate:flavodo ...	1983	6352705
new assay for enzymatic phosphate release: application to aspartate transcarbamylase and other enzymes.	the colorimetric method for phosphate determination described in the preceding paper is adapted for the assay of orthophosphate liberated in the aspartate transcarbamylase reaction. the method provides for simple, accurate, and sensitive measurement of enzyme activity. the assay uses ammonium molybdate and zinc acetate to form a colored complex with the enzymatically released phosphate; mild conditions which minimize the nonenzymatic background degradation of the substrate, carbamoyl phosphate, ...	1983	6353998
interaction of nitrogenase with nucleotide analogs of atp and adp and the effect of metal ions on adp inhibition.	the interaction of a large number of atp and adp analogs with nitrogenase from azotobacter vinelandii, klebsiella pneumoniae, and clostridium pasteurianum has been examined. only 1,n6-etheno-atp and 2'-deoxy-atp served as substrates for acetylene reduction. other triphosphates including gtp, itp, 8-br-atp, alpha,beta-methylene atp, beta,gamma-methylene atp, 6-chloropurine riboside triphosphate, and amp-pnp were inert, showing less than 50% inhibition at levels up to two- to fivefold greater than ...	1983	6354096
influence of pn2 and pd2 on hd formation by various nitrogenases.	formation of hd from d2 has been demonstrated with nitrogenase preparations from azotobacter vinelandii, clostridium pasteurianum, klebsiella pneumoniae, and azospirillum sp. we conclude that the formation of hd from d2 is a general property of nitrogenases. however, the nitrogenases differ in their ki values for d2 (n2 fixation) and in their rates of catalyzing hd formation; among the nitrogenases tested, c. pasteurianum nitrogenase had the lowest activity for formation of hd. when contaminatin ...	1983	6354256
continuous culture of azotobacter vinelandii and candida lipolytica in artificial seawater.		1983	6355784
use of specialized microbial strains in the treatment of industrial waste and in soil decontamination.		1983	6357840
purification and properties of membrane-bound hydrogenase from azotobacter vinelandii.	uptake hydrogenase (ec 1.12) from azotobacter vinelandii has been purified 250-fold from membrane preparations. purification involved selective solubilization of the enzyme from the membranes, followed by successive chromatography on deae-cellulose, sephadex g-100, and hydroxylapatite. freshly isolated hydrogenase showed a specific activity of 110 mumol of h2 uptake (min x mg of protein)-1. the purified hydrogenase still contained two minor contaminants that ran near the front on sodium dodecyl ...	1984	6378882
effects of allosteric activation on the primary and secondary kinetic isotope effects for three amp nucleosidases.	kinetic isotope effects (v/k) were measured with amp nucleosidases isolated from azotobacter vinelandii, from a vmax mutant enzyme of a. vinelandii and from escherichia coli. specifically labeled amp substrates were used to measure 3h secondary and 14c primary kinetic isotope effects on the n-glycosidic bond hydrolysis of amp in the presence and absence of the allosteric activator, mgatp. use of the three enzymes, variable mgatp concentration, a poor substrate (damp), and variable ph has allowed ...	1984	6378909
molybdenum in nitrogenase.		1984	6383195
biosynthesis of iron-molybdenum cofactor in the absence of nitrogenase.	klebsiella pneumoniae accumulates molybdenum during nitrogenase derepression. the molybdenum is primarily in nitrogenase component i in the form of iron-molybdenum cofactor (femo-co). mutations in any of three genes (nifb, nifn, and nife) involved in the biosynthesis of femo-co resulted in very low molybdenum accumulation and in a molybdenum-free nitrogenase component i. a mutant lacking both subunits of nitrogenase component i accumulated 60% of the amount of molybdenum present in the wild type ...	1984	6384184
cloning and organisation of some genes for nitrogen fixation from azotobacter chroococcum and their expression in klebsiella pneumoniae.	by dna hybridisation, restriction fragments of genomic dna from azotobacter chroococcum and a. vinelandii bearing sequences homologous to klebsiella pneumoniae nitrogenase structural genes were detected. these were different in the two species and inconsistent with the arrangement of the homologous sequences as a contiguous cluster of unique genes. the use of a dna probe specific for nifh showed that in a. chroococcum two nifh-like sequences were present in the genome. from gene libraries for a. ...	1984	6394956
[encystment using different carbon substrates in azotobacter chroococcum].	carbon nutrition has a fundamental role in the encystment of bacteria of the genus azotobacter. the effect of liquid media with various organic carbon substrates on the encystment of 2 strains of azotobacter chroococcum was studied. both strains had been previously cultured in a glucose and mannitol liquid medium. strain 2087 showed the greatest degree of encystment (78%) with isopropanol and a very low percentage of cyst formation in the glucose and mannitol medium. in strain 1847 an important ...	1983	6400765
[azomonas agilis in the surface water of the environs of buenos aires].	in 1941, it was reported the presence of azomonas agilis in rivers near buenos aires city. to our knowledge no other study has been carried out since then, so that the object of this paper was to investigate some characteristics of this organism and its possible influence on the nitrogen balance in waters. the isolation was performed by the plate method, using a mineral base for azotobacter with different energy sources. calcium malate appeared to be the best for azomonas-like organisms. on pure ...	1983	6400766
overproduction of nitrogenase by nitrogen-limited cultures of rhodopseudomonas palustris.	rhodopseudomonas palustris cells grown on limiting nitrogen produced four- to eightfold higher nitrogenase specific activity relative to cells sparged with n2. the high activity of n-limited cells was the result of overproduction of the nitrogenase proteins. this was shown by four independent techniques: (i) titration of the mo-fe protein in cell-free extracts with fe protein from azotobacter vinelandii; (ii) direct detection of the subunits of mo-fe protein by sodium dodecyl sulfate-polyacrylam ...	1983	6402491
sequences of the 5s rrnas of azotobacter vinelandii, pseudomonas aeruginosa and pseudomonas fluorescens with some notes on 5s rna secondary structure.	recently published alignments of available 5 s rrna sequences have shown that a rigid base pairing pattern, pointing to the existence of a universal five-helix secondary structure for all 5 s rnas, can be superimposed on such alignments. for a few species, the alignment and the base pairing pattern show distortions with respect to the large majority of sequences. their 5 s rnas may form exceptional secondary structures, or there may just be errors in the published sequences. we have examined suc ...	1983	6402760
adenine nucleotide levels in and nitrogen fixation by the cyanobacterium anabaena sp. strain 7120.	adenine nucleotide levels were determined in whole filaments of anabaena sp. 7120 grown under different n2-fixing or non-n2-fixing conditions. these were compared with levels in isolated heterocysts, rhodospirillum rubrum, and azotobacter vinelandii. adenine nucleotides in whole filaments of anabaena sp. do not reflect the energetic expense of n2 fixation as they do in r. rubrum and a. vinelandii. however, adenine nucleotide levels in heterocysts were similar to the levels found in n2-fixing r. ...	1983	6403506
d-(-)-poly-beta-hydroxybutyrate in membranes of genetically competent bacteria.	d-(-)-poly-beta-hydroxybutyrate is a constituent of the membranes and the cytoplasms of genetically competent azotobacter vinelandii, bacillus subtilis, and haemophilus influenzae cells. within each species the concentration of d-(-)-poly-beta-hydroxybutyrate in the membranes and cytoplasm correlates with transformability. fluorescence analysis of the thermotropic lipid phase transitions in a. vinelandii and b. subtilis cells indicates that d-(-)-poly-beta-hydroxybutyrate forms an organized gel ...	1983	6415039
classification of iron-sulfur cores in ferredoxins by 1h nuclear magnetic resonance spectroscopy.	a 1h nuclear magnetic resonance (nmr) study was carried out on various ferredoxins which possess one of three types of iron-sulfur clusters, (2fe-2s), (3fe-3s), or (4fe-4s). in the isolated form, (2fe-2s) ferredoxins from spinach (spinacea oleracia), pokeweed (phytolacca americana), a blue-green alga (spirulina platensis), and a halobacterium (halobacterium halobium) exhibited two broad resonances common in chemical shift at the region downfield of 10 ppm. in their reduced forms, seven contact-s ...	1983	6417123
uptake of methionine sulfoximine by some n2 fixing bacteria, and its effect on ammonium transport.	the n2 fixing bacteria klebsiella pneumoniae, azospirillum brasilense, rhodopseudomonas sphaeroides and rhodospirillum rubrum, but not azotobacter vinelandii accumulate the glutamine analogue methionine sulfoximine in the cell. in the accumulating cells methionine sulfoximine inhibits ammonium transport. accumulation and inhibition are prevented by glutamine.	1983	6418571
incorporation of isotope from specifically labeled glucose into alginates of pseudomonas aeruginosa and azotobacter vinelandii.	the incorporation of isotope from [6-14c]glucose into alginate by both pseudomonas aeruginosa and azotobacter vinelandii was 10-fold greater than that from either [1-14c]- or [2-14c]glucose, indicating preferential utilization of the bottom half of the glucose molecule for alginate synthesis. these data strongly suggest that the entner - doudoroff pathway plays a major role in alginate synthesis in both p. aeruginosa and a. vinelandii.	1984	6427189
siderophore-mediated uptake of iron in azotobacter vinelandii.	azotobacter vinelandii produces two siderophores, n,n'-bis-(2,3-dihydroxybenzoyl)-l-lysine (azotochelin) and a yellow-green fluorescent peptide (azotobactin), under iron-limited growth conditions. 55fe uptake was not observed until the substantial nonspecific binding of 55fe to the cell surface was eliminated by the addition of 10 mm sodium citrate to the uptake medium. citrate alone did not promote rapid 55fe uptake in a. vinelandii, nor did it induce fe-repressible outer membrane proteins. sid ...	1984	6429124
spectral properties of a mixture of fluorescent pigments produced by pseudomonas aeruginosa.	the major chromophore of a mixture of fluorescent pigments produced by pseudomonas aeruginosa atcc 9027 had ph-dependent absorption, excitation, and emission spectra, such that two ionic forms existed in the ground state and three in the excited states. the pigments could complex with several metal ions to change fluorescence and absorption spectra. although the pigments were separable into several components, spectra indicated that the same fluorescent chromophore was present in each component. ...	1984	6430349
[role of adenosine triphosphatase on nitrogenase function].	the decoupling possibility of atpase reaction with electron transfer process in the time of nitrogenase photolysis by lambda 435 nm light has been established. the cooh and the possibility of imidazole groups have been revealed in nitrogenase atpase centre by methods of chemical modification. the reaction of direct 18o-exchange between inorganic phosphate and medium water was discovered, proceeding under reverse hydrolysis of acylphosphate bond, formed by phosphorylation of cooh-group in atpase ...	1980	6453279
[distribution of an 18o isotope label in the products of atpase and polynucleotide phosphorylase reactions].		1980	6457996
the composition of the pyruvate dehydrogenase complex from azotobacter vinelandii. does a unifying model exist for the complexes from gram-negative bacteria?	an improved purification procedure of the pyruvate dehydrogenase complex of azotobacter vinelandii is described. this procedure minimizes losses of components and results in the isolation of the pure complex with a specific activity of 15-19 u/mg and an overall yield of 40%. the chain ratio of the three components was determined by covalent modification of the lysine residues with trinitrobenzene sulfonic acid, followed by separation of the components on sodium dodecyl sulfate gels. these determ ...	1984	6468378
the fate of methoxychlor in soils and transformation by soil microorganisms.	methoxychlor was found to be sufficiently persistent in soil and its residues were present even 18 months after the soil treatment. saprophytes, fungi and actinomyces were unaffected by varying concentrations of methoxychlor, azotobacter however was susceptable. soil strains isolated did not utilize methoxychlor as a sole carbon source except for 9 cultures belonging to the genera bacillus, acinetobacter and rhodococcus which carried out the complete dechlorination, demethylation and splitting o ...	1984	6491174
production of cyanocobalamine by azotobacter chroococcum.	a strain of azotobacter chroococcum was found to produce a considerable amount of cyanocobalamine especially when cultivated in a medium enriched with 0.3% ammonium chloride. maximal production of the vitamin was achieved after six days of incubation in static cultures. the organism required molybdenum, iron (fe++), cobalt and ascorbic acid for optimal production of cyanocobalamine. the initial supplementation of the medium with cyanocobalamine did not affect the formation of the vitamin. the le ...	1984	6495900
ubiquinone in hydrogen metabolism by azotobacter vinelandii.	extraction with n-heptane abolished over 95% of the nadh oxidase and the hydrogenase activity in membrane preparations from azotobacter vinelandii. incorporation of ubiquinone-8 or plastoquinone restored each reaction to about 55% of its original activity.	1984	6518422
preliminary crystallographic studies on bacterioferritin from azotobacter vinelandii.	bacterioferritin-cytochrome from azotobacter vinelandii is an unusual protein containing haem groups as well as iron core like other ferritin. this paper reports the purification of bacterioferritin by affinity chromatography and the formation of brick-red crystals from a solution containing mgcl2. the crystals are optical isotropic with maximum dimensions of 0.4 x 0.4 x 0.1 mm3. the preliminary x-ray crystallographic studies have been performed. 1.5 degrees unscreened precession photographs sho ...	1984	6528285
fully active fe-protein of the nitrogenase from azotobacter vinelandii contains at least eight iron atoms and eight sulphide atoms per molecule.	the fe-protein of the azotobacter vinelandii nitrogenase enzyme complex contains a variable iron and sulphide content. the iron and sulphide content of the protein is dependent upon the specific activity. up to a specific activity of 1000 nmol c2h4 produced x min-1 x mg av-1(2), three iron and three sulphide atoms per molecule av2 are found. at specific activities above 1000 nmol c2h4 produced x min-1 x mg av-1(2), a linear relationship between specific activity and iron and sulphide content of ...	1983	6574018
heat sensitivity of azotobacter vinelandii genetic transformation.	heating competent azotobacter vinelandii at 37 or 42 degrees c resulted in a total loss of competence with no loss of viability. the transformation process was relatively insensitive to heating at either temperature once dnase-resistant dna binding was nearly complete. although competent and 42 degrees c-treated cells bound equivalent amounts of [32p]dna in a dnase-resistant state, no donor dna marker (nif) or radioactivity was detected in the envelope-free cell lysate of heated cells, suggestin ...	1983	6575010
whole cell respiration and nitrogenase activities in azotobacter vinelandii growing in oxygen controlled continuous culture.		1983	6575734
[the study of the chemical composition of nitrogenase fe-mo-cofactor by a new fluorimetric method of thiocompound analysis].	a purification technique for a large scale production of crystalline mo-fe protein of nitrogenase from azotobacter vinelandii and of its fragment, fe-mo-cofactor (fe-mo-co) in argon atmosphere has been elaborated. the novel fluorimetric method of thiol compounds analysis has been proposed for identification of fe-mo-co thiol ligands; this procedure allows the determination of concentration and class of thiol compounds and of the distance between sulphur atoms in the case of dithiols. the use of ...	1983	6577914
on the formation of an oxygen-tolerant three-component nitrogenase complex from azotobacter vinelandii.	conditions are defined in which the oxygen-labile nitrogenase components from azotobacter vinelandii can be protected against oxygen inactivation by the so-called fe/s protein ii. it is demonstrated that oxygen protection can be achieved by complex formation of the three proteins. complex formation was studied by gel chromatography. only when the three proteins are in the oxidized state and mgcl2 is present, can an oxygen-tolerant complex be isolated. quantitative sds/polyacrylamide gel electrop ...	1983	6578037
structure of the mo-fe protein component of azotobacter vinelandii nitrogenase. analytical ultracentrifugation and electron microscopy studies.	the mo-fe protein of nitrogenase from both azotobacter vinelandii and klebsiella pneumoniae (av1 and kp1, respectively) consists of four subunits of similar, but not identical, relative molecular mass. the hydrodynamic properties of av1 (sedimentation and diffusion coefficient) and its total relative molecular mass are very similar to those of kp1 and catalase from bovine liver, a tetramer of four identical subunits. by electron microscopy the av1, kp1 and catalase tetramers are seen as protein ...	1983	6578928
crystallization of the azotobacter vinelandii nitrogenase iron protein.	the iron protein from azotobacter vinelandii nitrogenase has been crystallized in the reduced form. the needle-shaped crystals are in space group p2(1)2(1)2 (a = 94.6 a, b = 179.9 a, c = 74.1 a) and diffract to at least 3.5-a resolution. five or six fe-protein monomers are present in the asymmetric unit.	1983	6579051
thiol reactivity of the nitrogenase fe-protein from azotobacter vinelandii.	a procedure has been developed to examine some of the functional roles of the 14 cysteinyl residues in the nitrogenase fe-protein (av2) from azotobacter vinelandii. the reduced form of av2 was alkylated with iodo[2-14c]acetic acid under a variety of experimental conditions, e.g. reaction in the presence of nucleotides, alpha,alpha'-dipyridyl and nucleotides, or denaturants. the labeled cysteinyl residues were identified and quantified using an analytical deae-sepharose ion exchange chromatograph ...	1983	6580291
inhibition of nitrogenase activity by ammonium chloride in azotobacter vinelandii.	in azotobacter vinelandii cells, the short-term inhibition of nitrogenase activity by nh4cl was found to depend on several factors. the first factor is the dissolved oxygen concentration during the assay of nitrogenase. when cells are incubated with low concentrations of oxygen, nitrogenase activity is low and ammonia inhibits strongly. with more oxygen, nitrogenase activity increases. cells incubated with an optimum amount of oxygen have maximum nitrogenase activity, and the extent of inhibitio ...	1984	6581156
short-term ammonium inhibition of nitrogen fixation in azotobacter.	addition of nh4cl at low concentrations to azotobacter chroococcum cells caused an immediate cessation of nitrogenase activity, which was recovered once the added nh+4 was exhausted from the medium. in the presence of inhibitors of ammonium assimilation, such as l-methionine-dl-sulfoximine, l-methionine sulfone or 6-diazo-5-oxo-l-norleucine, externally added nh+4 had no effect on nitrogenase activity and the newly-fixed nitrogen was excreted into the medium as nh+4. it is concluded that, in a. c ...	1984	6593068
characteristics of n2 fixation in mo-limited batch and continuous cultures of azotobacter vinelandii.	steady-state chemostat cultures of azotobacter vinelandii were established in a simple defined medium that had been chemically purified to minimize mo and that contained no utilizable combined n source. growth was dependent on n2 fixation, the limiting nutrient being the mo contaminating the system. the mo content of the organisms was at least 100-fold lower than that of mo-sufficient cultures, and they lacked the characteristic g = 3.7 e.p.r. feature of the mofe-protein of nitrogenase. a charac ...	1984	6596950
binding of mgatp to the nitrogenase proteins from azotobacter vinelandii.	binding of mgatp to the mofe and fe proteins from azotobacter vinelandii has been studied. by means of the flow dialysis technique it was demonstrated that one molecule of reduced fe protein binds one molecule of mgatp, with a dissociation constant of 0.56 +/- 0.11 mm. the oxidized fe protein binds two molecules of mgatp, with identical intrinsic dissociation constants of 0.29 +/- 0.05 mm. the binding of mgatp to the fe protein was also studied by equilibrium dialysis. it was found that during d ...	1983	6601579
nitrogenase reactivity: methyl isocyanide as substrate and inhibitor.	we have examined the interaction of methyl isocyanide with the purified component proteins of azotobacter vinelandii nitrogenase (av1 and av2). ch3nc was shown to be a potent reversible inhibitor (ki = 158 microm) of total electron flow, apparently uncoupling magnesium adenosine 5'-triphosphate hydrolysis from electron transfer to substrate. ch3nc is a substrate (km = 0.688 mm at av2/av1 = 8), and extrapolation of the data indicates that at high enough ch3nc concentration, h2 evolution can be el ...	1983	6607071
a rapid and sensitive paper electrophoresis assay for the detection of microbial siderophores elicited in solid-plating culture.	a rapid and sensitive assay for the detection of microbial siderophores (iron-binding compounds) is described. nine representative fungal and bacterial cultures including ustilago sphaerogena, penicillium sp., fusarium roseum, rhodotorula pilimanae, bacillus subtilis w 23, bacillus subtilis w 168, bacillus megaterium, azotobacter vinelandii op, and escherichia coli b, were nutritionally stressed for iron by sequential transfers on iron-deficient solid-plating media. in response to fe-stress cond ...	1983	6614486
[detection of extrachromosomal dna in azotobacter chroococcum strains].		1983	6641486
resonance raman spectroscopy of azotobacter vinelandii ferredoxin i. vibrational features of the [3fe-3s] cluster.	low temperature resonance raman spectra have been obtained for clostridium pasteurianum and bacillus stearothermophilus ferredoxins. several heretofore undetected fundamental bands have been observed and these data have been used to discriminate the vibrational contribution of the [3fe-3s] cluster to the spectrum of azotobacter vinelandii ferredoxin i. the vibrational features of the [3fe-3s] core distinguish it from other 3-iron clusters and imply structural differences among this class of iron ...	1983	6641938
protein turnover in azotobacter vinelandii during encystment and germination.	protein turnover occurs during differentiation of azotobacter vinelandii 12837 to the extent of 50% during encystment and 7% during germination. the addition of rifampin at the initiation of encystment prevents encystment and inhibits turnover. in germinating cysts, protein turnover is essential owing to an apparent lack of certain amino acid biosynthetic enzymes. the capacity to synthesize sulfur-containing amino acids from inorganic precursors is regained about halfway through the germination ...	1983	6643391
presence of a new cytochrome b - like pigment with a peak at 567 nm in various aerobic bacteria.	several physiological groups of bacteria were examined for the presence of a cytochrome b - like pigment which is demonstrable in dithionite-reduced minus substrate-reduced difference spectra. this pigment is characterized by an unusually high alpha band at 567 nm, a low concentration relative to conventional cytochromes, and an inability to be fully reduced by endogenous substrates or nadh. previous studies with one denitrifying and nondenitrifying species of the genus pseudomonas, in paracoccu ...	1983	6652580
a filtration method for measuring cellular uptake of [14c]methylamine and other highly permeant solutes.	a filtration technique has been developed for study of the uptake of [14c]methylamine by azotobacter vinelandii. this dual filter arrangement requires a precision microporous polycarbonate film which overlays a paper filter. cellular uptake of radioactivity is terminated by vacuum filtration of the reaction mixture onto the polycarbonate filter without dilution or washing. filtration was complete in 0.7 s with retention of less than 0.2% of the extracellular radioactivity. the dual filter method ...	1983	6660521
an improved purification procedure and apoprotein preparation for the flavodoxin from azotobacter vinelandii.	an improved method for the purification of the holoflavodoxin from azotobacter vinelandii was developed, which resulted in improved yields and degree of homogeneity. the purity and homogeneity of this sample were established by polyacrylamide gel electrophoresis. an apoprotein preparation procedure is outlined, which results in a homogeneous preparation of the apoflavodoxin. the homogeneity of the apoflavodoxin sample was established by polyacrylamide gel electrophoresis.	1983	6669519
crystallization and preliminary x-ray investigation of lipoamide dehydrogenase from azotobacter vinelandii.	the fad-containing enzyme lipoamide dehydrogenase (ec 1.6.4.3. nadh: lipoamide oxidoreductase) of azotobacter vinelandii has been crystallized from polyethylene glycol solutions. the space group is p2(1)2(1)2(1) with one dimer in the asymmetric unit. the cell dimensions are: a = 64.2, b = 83.8, c = 193 a. x-ray reflections extend to at least 2.2 a resolution.	1983	6687741
characterization of the fe-s cluster in aconitase using low temperature magnetic circular dichroism spectroscopy.	beef heart aconitase has been studied by low temperature magnetic circular dichroism (mcd) spectroscopy in the wavelength region 300 to 1900 nm. together with parallel electron paramagnetic resonance and activity measurements, these data enable correlations between fe-s cluster-type and enzymic activity in aconitase. in samples not exposed to extraneous fe, the fe-s cluster in aconitase exhibits the characteristic properties of a 3fe center in both the as isolated and dithionite-reduced states. ...	1984	6698964
the thermodynamics of flavin binding to the apoflavodoxin from azotobacter vinelandii.	a thermodynamic study of the binding of flavins (fmn, fad, 8-carboxylic acid-riboflavin) to the purified apoflavodoxin from azotobacter vinelandii has been conducted. the binding of fmn was studied at a number of temperatures (10, 15, 20, 25, and 30 degrees c), ph's (6.0, 7.4, and 9.0), and buffer conditions. the binding of fad was studied at ph 7.4 and 25 degrees c under a number of buffer conditions. the binding of 8-carboxylic acid-riboflavin to the apoflavodoxin and the binding of fmn to the ...	1984	6703704
the size of the pyruvate dehydrogenase complex of azotobacter vinelandii. association phenomena.	sedimentation analysis and light-scattering studies indicate that the aggregation state of the pyruvate dehydrogenase complex of azotobacter vinelandii in 50 mm potassium phosphate (ph 7.0) can be described in terms of a monomer-dimer equilibrium with a dissociation constant of 6.8 microm. the apparent molecular mass of the monomeric particle is 750 000-850 000 da. the equilibrium is shifted to the monomeric species when pressure is applied on the system. pressure-jump experiments yielded a rela ...	1984	6714233
the role of glutamine in regulation of ammonium transport in azotobacter vinelandii.	under n2-fixing conditions, azotobacter vinelandii expresses a specific transport system for methylammonium (ammonium) [e. m. barnes, jr. and p. zimniak (1981) j. bacteriol. 146, 512-516]. this activity is decreased markedly by culture of cells in the presence of 10 mm ammonium or 2 mm methylammonium; in both cases, the vmax values for methylammonium uptake were 25% of those of n2-fixing cells. mixing experiments with assay medium indicate that transport activity is controlled by intracellular r ...	1984	6721503
toxicity of dicamba (2-methoxy-3,6-dichlorobenzoic acid) to azotobacter vinelandii.	the effect of dicamba was studied in n-free medium inoculated with azotobacter vinelandii atcc 12837. nitrogen fixation was determined by acetylene reduction. dicamba at a concentration of 500 micrograms/ml had a strong inhibitory effect on nitrogenase activity. however, no inhibitory effect on microbial respiration was detected.	1984	6724435
regular surface layer of azotobacter vinelandii.	washing azotobacter vinelandii uw1 with burk buffer or heating cells at 42 degrees c exposed a regular surface layer which was effectively visualized by freeze-etch electron microscopy. this layer was composed of tetragonally arranged subunits separated by a center-to-center spacing of approximately 10 nm. cells washed with distilled water to remove an acidic major outer membrane protein with a molecular weight of 65,000 did not possess the regular surface layer. this protein, designated the s p ...	1984	6735982
hydrogen-oxidizing electron transport components in nitrogen-fixing azotobacter vinelandii.	membranes from n2-fixing azotobacter vinelandii were isolated to identify electron transport components involved in h2 oxidation. we found direct evidence for the involvement of cytochromes b, c, and d in h2 oxidation by the use of h2-reduced minus o2-oxidized absorption difference spectra. carbon monoxide spectra showed that h2 reduced cytochrome d but not cytochrome o. inhibition of h2 oxidation by cyanide was monophasic with a high ki (135 microm); this was attributed to cytochrome d. cyanide ...	1984	6735984
intergeneric evolutionary homology revealed by the study of protocatechuate 3,4-dioxygenase from azotobacter vinelandii.	protocatechuate 3,4-dioxygenase (ec 1.13.1.3) was purified to homogeneity from extracts of azotobacter vinelandii. the molecular weight of the oligomeric protein was estimated to be 510 000 by gel filtration and 480 000 by ultracentrifugation. the oligomer appears to be formed by association of equal amounts of nonidentical subunits which were estimated by sodium dodecyl sulfate gel electrophoresis to have respective molecular weights of 23 300 and 25 250. ten gram-atoms of iron was associated w ...	1980	6766312
oxygen and hydrogen in biological nitrogen fixation.		1980	6776883
evolutionary relationships among gamma-carboxymuconolactone decarboxylases.	gamma-carboxymuconolactone decarboxylase (ec 4.1.1.44) from azotobacter vinelandii resembled the isofunctional enzymes from acinetobacter calcoaceticus and pseudomonas putida. all three decarboxylases appeared to be hexamers formed by association of identical subunits of about 13,300 daltons. the a. vinelandii and p. putida decarboxylases cross-reacted immunologically with each other, and the nh2-terminal amino acid sequences of the enzymes differed in no more than 7 of the first 36 residues. in ...	1981	6783616
characterization of the predominant azotobacter vinelandii envelope protein.	a protein with a molecular weight of 60,000 (60k) constitutes approximately 20% of the envelope protein of azotobacter vinelandii. this protein was removed from cells and purified from other proteins by a simple washing procedure that had no effect on cell viability. anti-60k antiserum blocked azotophage a-22 adsorption and agglutinated both vegetative cells and cysts; ferritin-conjugated antibodies used in indirect labeling studies bound uniformly to the periphery of vegetative cells. we conclu ...	1981	6783619
photochemical action spectra of bacterial a- and o-type oxidases using a dye laser.		1981	6790302
a mutant amp nucleosidase. purification, properties, and in vivo turnover of the protein.		1981	6796578
the amino acid sequence of the nitrogenase iron protein from azotobacter vinelandii.		1982	6801032