| distinct structural features of the alpha and beta subunits of nitrogenase molybdenum-iron protein of clostridium pasteurianum: an analysis of amino acid sequences. | nitrogenase is composed of two separately purified proteins, a molybdenum-iron (mofe) protein and an iron (fe) protein. structural genes (nifd and nifk) encoding alpha and beta subunits of the mofe protein of clostridium pasteurianum (cp) have been cloned and sequenced. the deduced amino acid sequences were analyzed for structures that could be related to the unique properties of the cp protein, particularly its low capacity to form an active enzyme with a heterologous fe protein. cp nifk is loc ... | 1988 | 2840948 |
| comparison of redox and epr properties of the molybdenum iron proteins of clostridium pasteurianum and azotobacter vinelandii nitrogenases. | both heterologous crosses of the clostridium pasteurianum and azotobacter vinelandii nitrogenase components are completely inactive, although the reasons for this incompatibility are not known. we have compared a number of properties of the mofe proteins from these organisms (cp1 and av1, respectively) in an attempt to find differences that could explain this lack of functional activity. optical and cd spectroscopic titrations are similar for both av1 and cp1, but epr titrations are significantl ... | 1988 | 2842451 |
| free and membrane-bound forms of bacterial cytochrome c4. | cytochrome c4 was isolated from cells of pseudomonas aeruginosa, pseudomonas stutzeri and azotobacter vinelandii. the dihaem nature, mr of approx. 20,000 and ferrohaem spectra in the region of the alpha- and beta-peaks define this family of cytochromes c. the behaviour of the holocytochromes in sds was atypical, but removal of the haem groups resulted in a normal migration. in all three organisms most of the cytochrome c4 was tightly bound to the membrane, but some free cytochrome was detected. ... | 1988 | 2843169 |
| redox reactivity of bacterial and mammalian ferritin: is reductant entry into the ferritin interior a necessary step for iron release? | both mammalian and bacterial ferritin undergo rapid reaction with small-molecule reductants, in the absence of fe2+ chelators, to form ferritins with reduced (fe2+) mineral cores. large, low-potential reductants (flavoproteins and ferredoxins) similarly react anaerobically with both ferritin types to quantitatively produce fe2+ in the ferritin cores. the oxidation of fe2+ ferritin by large protein oxidants [cytochrome c and cu(ii) proteins] also occurs readily, yielding reduced heme and cu(i) pr ... | 1988 | 2845407 |
| mössbauer studies of solid thionin-oxidized mofe protein of nitrogenase. | recently hagen et al. (hagen, w. r., wassink, h., eady, r. r., smith, b. e., and haaker, h. (1987) eur. j. biochem. 169, 457-465) reported the observation of s = 7/2 epr signals for thionin-oxidized nitrogenase mofe protein. here we have studied the protein from azotobacter vinelandii and klebsiella pneumoniae with mössbauer and epr spectroscopies, with the following results: when the mofe protein is oxidized by addition of stoichiometric amounts (6-8 equivalents) of dissolved thionin, the well ... | 1988 | 2848826 |
| the vanadium nitrogenase of azotobacter chroococcum. purification and properties of the fe protein. | 1. nitrogenase activity of a strain of azotobacter chroococcum lacking the structural genes of monitrogenase (nifhdk) was associated with a v + fe-containing protein and an fe-containing protein [robson, eady, richardson, miller, hawkins & postgate (1986) nature (london) 322, 388-390; eady, robson, richardson, miller & hawkins (1987) biochem. j. 244, 197-207]. 2. the fe protein was purified to homogeneity by the criterion of coomassie blue staining after electrophoresis in 10% or 17% (w/v) polya ... | 1988 | 2851977 |
| the dna gyrase inhibitors, nalidixic acid and oxolinic acid, prevent iron-mediated repression of catechol siderophore synthesis in azotobacter vinelandii. | low concentrations of nalidixic acid and oxolinic acid that were just inhibitory to azotobacter vinelandii growth promoted the production of the catechol siderophores azotochelin and aminochelin, in the presence of normally repressive concentrations of fe3+. there was a limited effect on the pyoverdin siderophore, azotobactin, where low concentrations of fe3+ were rendered less repressive, but the repression by higher concentrations of fe3+ was normal. these drugs did not induce high-molecular-m ... | 1988 | 2856355 |
| regulation of nitrogen metabolism in azotobacter vinelandii: isolation of ntr and glna genes and construction of ntr mutants. | the ntra, ntrb and ntrc products are responsible for regulating the transcription of many genes involved in the assimilation of poor nitrogen sources in enteric bacteria. the presence of a similar system in the non-enteric bacterium azotobacter vinelandii is reported here. genes analogous to ntra and ntrc were isolated from an a. vinelandii gene library by complementation of escherichia coli mutants. the gene encoding glutamine synthetase, glna, was also isolated and found to be adjacent to ntrc ... | 1986 | 2872049 |
| genetic evidence for an azotobacter vinelandii nitrogenase lacking molybdenum and vanadium. | we have constructed a strain of azotobacter vinelandii which has deletions in the genes for both the molybdenum (mo) and vanadium (v) nitrogenases. this strain fixed nitrogen in medium that did not contain mo or v. growth and nitrogenase activity were inhibited by mo and v. in highly purified medium, growth was limited by iron. addition of other metals (co, cr, cu, mn, ni, re, ti, w, and zn) did not stimulate growth. like the v-nitrogenase, the nitrogenase synthesized by the double deletion stra ... | 1989 | 2914845 |
| the quaternary structure of the dihydrolipoyl transacetylase component of the pyruvate dehydrogenase complex from azotobacter vinelandii. a reconsideration. | after limited proteolysis of the dihydrolipoyl transacetylase component (e2) of azotobacter vinelandii pyruvate dehydrogenase complex (pdc), a c-terminal domain was obtained which retained the transacetylase active site and the quaternary structure of e2 but had lost the lipoyl-containing n-terminal part of the chain and the binding sites for the peripheral components, pyruvate dehydrogenase and lipoamide dehydrogenase. the c-terminus of this domain was determined by treatment with carboxypeptid ... | 1989 | 2917567 |
| refinement of the 7 fe ferredoxin from azotobacter vinelandii at 1.9 a resolution. | the recently redetermined structure of the 7 fe ferredoxin from azotobacter vinelandii has been refined against a new 1.9 a data set. the crystallographic r-factor is 0.215 for all 9586 observed reflections 8.0 to 1.9 a. the model contains 106 amino acid residues, two fe-s clusters and 21 water molecules. the root-mean-square deviations from ideality of bonds and angles are 0.014 a and 3.3 degrees, respectively. the refinement confirms the presence of two free cysteines: the thiol of c11 is in a ... | 1989 | 2926817 |
| binding of adp and orthophosphate during the atpase reaction of nitrogenase. | the pre-steady-state atpase activity of nitrogenase from azotobacter vinelandii was investigated. by using a rapid-quench technique, it has been demonstrated that with the oxidized nitrogenase complex the same burst reaction of mgatp hydrolysis occurs as observed with the reduced complex, namely 6-8 mol orthophosphate released/mol mofe protein. it is concluded that the pre-steady-state atpase activity is independent of electron transfer from fe protein to mofe protein. results obtained from gel ... | 1987 | 2948821 |
| the role of mgatp hydrolysis in nitrogenase catalysis. | kinetic studies on mgatp hydrolysis by nitrogenase of azotobacter vinelandii were performed in the presence and in the absence of reducing equivalents. by measuring the atpase activity of dye-oxidized nitrogenase proteins it can be excluded that reductant-independent atpase activity is the result of futile cycling of electrons. the turnover rates of mofe protein during reductant-dependent and reductant-independent atpase activity, when measured with excess fe protein, have approximately the same ... | 1988 | 2965012 |
| in vivo interaction between nitrogenase molybdenum-iron protein and membrane in azotobacter vinelandii and rhodospirillum rubrum. | oriented whole cell multilayers of azotobacter vinelandii and rhodospirillum rubrum were analyzed by electron spin resonance (esr) spectroscopy to detect possible structural associations between nitrogenase molybdenum-iron (mofe) protein and cytoplasmic or intracytoplasmic membrane. initially, protocols were designed to obtain strong molybdenum-iron protein esr signals in whole cell samples of each organism. then, two-dimensional orientation of whole cell membranes was demonstrated in whole cell ... | 1985 | 2981550 |
| immunological investigation of the distribution of cytochromes related to the two terminal oxidases of escherichia coli in other gram-negative bacteria. | monospecific antibodies were raised against the two terminal oxidase complexes of the aerobic respiratory chain of escherichia coli. these are the cytochrome d and cytochrome o complexes. the antibodies were used to check for the occurrence of cross-reactive antigens in membrane preparations from a variety of gram-negative bacteria by rocket immunoelectrophoresis and immunoblotting techniques. with these criteria, proteins closely related to the cytochrome d complex of e. coli appeared to be wid ... | 1985 | 2981822 |
| selective oxidative destruction of iron-sulfur clusters. ferricyanide oxidation of azotobacter vinelandii ferredoxin i. | the destructive oxidation of aerobically isolated 7fe azotobacter vinelandii ferredoxin i [(7fe)fdi] by fe(cn)3-6 is examined using low-temperature magnetic circular dichroism (mcd) and epr. the results demonstrate that oxidation of the [3fe-3s] cluster occurs only after essentially complete destruction of the [4fe-4s] cluster. it is therefore feasible by controlled fe(cn)3-6 oxidation to obtain a partially metallated form of fdi, (3fe)fdi, containing only a [3fe-3s] cluster. the mcd and epr dat ... | 1985 | 2985428 |
| complex formation between flavodoxin and cytochrome c. cross-linking studies. | complex formation between azotobacter vinelandii flavodoxin and horse cytochrome c has been demonstrated through cross-linking studies with dimethyl suberimidate, dimethyl adipimidate, 1-ethyl-3-(3-di-methylaminopropyl)carbodiimide, and dimethyl-3,3'-dithiobispropionimidate. essentially quantitative cross-linking of cytochrome c and flavodoxin was observed at low ionic strengths with the carbodiimide cross-linking reagent. an association constant of 4 x 10(4) m-1 was obtained between cytochrome ... | 1985 | 2985577 |
| a study of one of the iron-sulphur clusters in oxidized hydrogenase from megasphaera elsdenii by magnetic-circular-dichroism spectroscopy. | the m.c.d. spectrum of the oxidized state of hydrogenase from megasphaera elsdenii has been measured at liquid-helium temperatures. this oxidation state of the enzyme displays a characteristic rhombic e.p.r. signal with g-values of 2.101, 2.052 and 2.005 assigned previously to a [4fe-4s]3+ cluster as in oxidized hipip (high-potential iron-sulphur protein) [van dijk, grande, mayhew & veeger (1980) eur. j. biochem. 107, 251-261]. the low-temperature m.c.d. spectrum shows no features attributable t ... | 1985 | 2986607 |
| complex formation and o2 sensitivity of azotobacter vinelandii nitrogenase and its component proteins. | the o2 stability of the mofe protein, the fe protein, a 1:1 mixture of these proteins, and a 1:1 mixture in the presence of the azotobacter vinelandii fes-ii protein has been studied as a function of time under controlled o2 partial pressures. the fe protein is much more sensitive to o2 exposure than is the mofe protein. the presence of the fes-ii protein at a 1:1 ratio with the component proteins measurably increases the o2 stability of the mofe and fe proteins. o2 inactivation of the mofe prot ... | 1985 | 2986674 |
| complexity in the redox titration of the dihaem cytochrome c4. | redox titration of the dihaem, two domain cytochromes c4 from pseudomonas aeruginosa, pseudomonas stutzeri and azotobacter vinelandii showed complex behaviour indicative of the presence of two redox components. in the case of the p. stutzeri cytochrome c4, two spectroscopically distinct components were present during the redox titration. in contrast, cytochrome c-554(548) from a halophilic paracoccus species is a stable dimer of a monohaem cytochrome which shows close homology to cytochrome c4, ... | 1985 | 2990552 |
| on the prosthetic group(s) of component ii from nitrogenase. epr of the fe-protein from azotobacter vinelandii. | the epr spectrum of the reduced fe-protein from nitrogenase has been reinvestigated. the dependences on temperature, microwave power, and microwave frequency all suggest that the observed signal represents a magnetically isolated [4fe-4s]1+(2+;1+) cluster. also, the signal can be simulated assuming a simple, g-strained s = 1/2 system. however, the integrated intensity amounts to no more than 0.2 spins per protein molecule. it is, therefore, impossible that fe-protein preparations contain a singl ... | 1985 | 2991004 |
| electron-paramagnetic-resonance spectroscopy and related techniques in the study of nitrogenase. | | 1985 | 2993065 |
| mössbauer, epr, and magnetization studies of the azotobacter vinelandii fe protein. evidence for a [4fe-4s]1+ cluster with spin s = 3/2. | we have studied the fe protein (av2) of the azotobacter vinelandii nitrogenase system with mössbauer and epr spectroscopies and magnetic susceptometry. in the oxidized state the protein exhibits mössbauer spectra typical of diamagnetic [4fe-4s]2+ clusters. addition of mg.atp or mg.adp causes a pronounced decline in the quadrupole splitting of the mössbauer spectra of the oxidized protein. our studies show that reduced av2 in the native state is heterogeneous. approximately half of the molecules ... | 1985 | 2993304 |
| crystal structure of azotobacter cytochrome c5 at 2.5 a resolution. | the crystal structure of cytochrome c5 from azotobacter vinelandii has been solved and refined to an r value of 0.29 at 2.5 a resolution. the structure of the oxidized protein was solved using a monoclinic crystal form. the structure was solved by multiple isomorphous replacements, re-fit to a solvent-leveled multiple isomorphous replacement map, and refined by restrained least squares. the structure reveals monomers associated about the crystallographic 2-fold axis by hydrophobic contacts at th ... | 1985 | 2993632 |
| [4fe-4s]-cluster-depleted azotobacter vinelandii ferredoxin i: a new 3fe iron-sulfur protein. | fe(cn)6(-3) oxidation of the aerobically isolated 7fe azotobacter vinelandii ferredoxin i, (7fe)fdi, is a degradative reaction. destruction of the [4fe-4s] cluster occurs first, followed by destruction of the [3fe-3s] cluster. at a fe(cn)6(-3)/(7fe)fdi concentration ratio of 20, the product is a mixture of apoprotein and protein containing only a [3fe-3s] cluster, (3fe)fdi. this protein mixture, after partial purification, has been characterized by absorption, cd, magnetic cd, and epr and fe x-r ... | 1985 | 2994040 |
| assignment of esr signals of escherichia coli terminal oxidase complexes. | the esr signals of all the major components of the aerobic respiratory chain of escherichia coli were measured and assigned at liquid helium temperature. cytochrome b-556 gives a weak high-spin signal at g = 6.0. the terminal oxidase cytochrome b-562 . o complex gives signals at g = 6.0, 3.0 and 2.26, and the terminal oxidase cytochrome b-558 . d complex gives signals at g = 6.0, 2.5 and 2.3. a signal derived from cupric ions in the purified cytochrome b-562 . o complex was observed near g = 2.0 ... | 1985 | 2994724 |
| a novel s = 3/2 epr signal associated with native fe-proteins of nitrogenase. | in addition to their g = 1.94 epr signal, nitrogenase fe-proteins from azotobacter vinelandii, azotobacter chroococcum and klebsiella pneumoniae exhibit a weak epr signal with g approximately equal to 5. temperature dependence of the signal was consistent with an s = 3/2 system with negative zero-field splitting, d = -5 +/- 0.7 cm-1. the ms = +/- 3/2 ground state doublet gives rise to a transition with geff = 5.90 and the transition within the excited ms = +/- 1/2 doublet has a split geff = 4.8, ... | 1985 | 2995120 |
| transfer of transposable drug-resistance elements tn5, tn7, and tn76 to azotobacter beijerinckii: use of plasmid rp4::tn76 as a suicide vector. | transposable elements tn5, tn7, and tn76 were transferred to azotobacter beijerinckii. evidence was obtained for the transposition of tn5 but cells of the majority of presumptive transposition isolates had abnormal morphologies and rapidly lost viability when subcultured. data are presented that indicate that plasmid rp4::tn76 behaves as a suicide vector upon transfer to this host, allowing the isolation of a. beijerinckii::tn76 isolates at a high frequency. nitrogen-fixing mutants and leucine a ... | 1985 | 2999852 |
| isolation and characterization of ack and pta mutations in azotobacter vinelandii affecting acetate-glucose diauxie. | azotobacter vinelandii mutants defective for acetate utilization that were resistant to fluoroacetate (fa) were isolated. fa-resistant mutant am6 failed to transport [14c]acetate and lacked enzymatic activity for both acetate kinase and phosphotransacetylase. growth of wild-type a. vinelandii was sensitive to 10 mm glycine; however, all fa-resistant strains were resistant to glycine toxicity. isolated mutants that were spontaneously resistant to glycine were also resistant to fa and lacked both ... | 1986 | 3001033 |
| the lack of a solvent accessible hydroxide or water ligand to iron at the 3fe center of azotobacter vinelandii ferredoxin i. | the x-ray crystal structure of azotobacter vinelandii ferredoxin i (fdi) describes a planar 3fe-3s center in which one of the iron atoms is ligated to a solvent accessible oxo ligand, presumably from water or hydroxide (ghosh et al., (1982) j. mol. biol. 158, 73-109). efforts to displace the proposed oxo ligand with cyanide were unsuccessful, even in 80% dimethylsulfoxide. in addition, comparison of the electron spin echo envelopes for h2o- and d2o-equilibrated samples of fdi showed only a sligh ... | 1985 | 3002366 |
| n-terminal amino acid sequence of cytochrome c-552 from nitrosomonas europaea. | nitrosomonas europaea is an ammonia-oxidizing bacterium which contains multiple c-type cytochromes. few of these components have been assigned physiological roles, but on the basis of molecular weight and redox potential cytochrome c-552 has been considered to be an analogue of the mitochondrial cytochrome-c family of proteins. we present the n-terminal amino acid sequence (47 residues) of cytochrome c-552 and show that this protein is most closely related to the group of small cytochrome-c comp ... | 1986 | 3004498 |
| in vitro synthesis of the iron-molybdenum cofactor of nitrogenase. | molybdate- and atp-dependent in vitro synthesis of the iron-molybdenum cofactor (femo-co) of nitrogenase requires the protein products of at least the nifb, nifn, and nife genes. extracts of femo-co-negative mutants of klebsiella pneumoniae and azotobacter vinelandii with lesions in different genes can be complemented for femo-co synthesis. both k. pneumoniae and a. vinelandii dinitrogenase (component i) deficient in femo-co can be activated by femo-co synthesized in vitro. properties of the par ... | 1986 | 3006060 |
| isolation of ntra-like mutants of azotobacter vinelandii. | a number of chlorate-resistant mutants of azotobacter vinelandii affected in a general control of nitrogen metabolism were isolated. these mutants could not utilize dinitrogen, nitrate, or nitrite as a nitrogen source. the reason for this inability is that they were simultaneously deficient in nitrogenase and nitrate and nitrite reductase activities. they were complemented by a cosmid carrying a dna fragment of a. vinelandii able to complement ntra mutants of escherichia coli, so they seemed to ... | 1986 | 3009406 |
| transcriptional regulation of nitrogen fixation by molybdenum in azotobacter vinelandii. | multiple genomic regions homologous to nifh were found in the diazotroph azotobacter vinelandii. the nifhdk gene cluster, located on a 12.8-kilobase (kb) xhoi fragment and two additional xhoi fragments (7.4 and 8.4 kb) hybridized to a nifh-specific dna template but the 7.4- and 8.4-kb fragments did not hybridize to nifd- or nifk-specific dna probes. in vivo transcription of the nifhdk gene cluster was ammonia-repressible and required the presence of at least 50 nm molybdenum in the derepression ... | 1986 | 3015874 |
| nifv-dependent, low-molecular-weight factor required for in vitro synthesis of iron-molybdenum cofactor of nitrogenase. | the molybdate- and atp-dependent in vitro synthesis of the iron-molybdenum cofactor of nitrogenase requires a low-molecular-weight factor. the factor is present in extracts of nitrogen fixation-derepressed cultures of klebsiella pneumoniae and azotobacter vinelandii, but not in extracts of repressed cultures of these bacteria. analysis of k. pneumoniae nif mutants has indicated that the nifv gene product is the only nif protein (besides nifa) necessary for the synthesis and accumulation of the f ... | 1986 | 3017921 |
| solubilization of the iron molybdenum cofactor of azotobacter vinelandii nitrogenase in dimethylformamide and acetonitrile. | the iron molybdenum cofactor of azotobacter vinelandii nitrogenase has been solubilized for the first time in dimethylformamide and acetonitrile. these solutions have the ability to reconstitute the inactive nitrogenase of the uw 45 mutant of a. vinelandii and exhibit an s = 3/2 epr signal similar to that for the cofactor in n-methylformamide. our ability to obtain solutions of femoco in these solvents seemingly refutes a previous hypothesis concerning the necessity of solvents with a dissociabl ... | 1986 | 3021140 |
| isolation and characterization of a second nitrogenase fe-protein from azotobacter vinelandii. | wild-type azotobacter vinelandii strain uw was transformed with plasmid pdb12 to produce a species (ls10) unable to synthesize the structural proteins of component 1 and component 2 of native nitrogenase. a spontaneous mutant of this strain was isolated (ls15) which can grow by nitrogen fixation in the presence or absence of either mo or w. it is proposed that ls15 fixes nitrogen solely by an alternative nitrogen-fixing system which previously has been hypothesized to exist in a. vinelandii. und ... | 1986 | 3021770 |
| tn5-induced mutants of azotobacter vinelandii affected in nitrogen fixation under mo-deficient and mo-sufficient conditions. | mutants of azotobacter vinelandii affected in n2 fixation in the presence of 1 microm na2moo4 (conventional system), 50 nm v2o5, or under mo deficiency (alternative system) have been isolated after tn5 mutagenesis with the suicide plasmid psup1011. these mutants can be grouped into at least four broad phenotypic classes. mutants in the first class are nif- under mo sufficiency but nif+ under mo deficiency or in the presence of v2o5. a nifk mutant and a mutant apparently affected in regulation of ... | 1986 | 3023285 |
| electron-transfer reactions between flavodoxin semiquinone and c-type cytochromes: comparisons between various flavodoxins. | as an extension of previous work from this laboratory using clostridium pasteurianum flavodoxin [tollin, g., cheddar, g., watkins, j. a., meyer, t. e., & cusanovich, m. a. (1984) biochemistry 23, 6345-6349], we have measured the rate constants as a function of ionic strength for electron transfer from the semiquinones of clostridium mp, anacystis nidulans, and azotobacter vinelandii flavodoxins to the following oxidants: cytochrome c from tuna and horse, paracoccus denitrificans cytochrome c2, p ... | 1986 | 3024711 |
| spectroscopic studies of the seven-iron-containing ferredoxins from azotobacter vinelandii and thermus thermophilus. | the seven-iron-containing ferredoxins from azotobacter vinelandii and thermus thermophilus have been investigated by low-temperature magnetic circular dichroism (mcd) and electron paramagnetic resonance (epr) spectroscopies and room temperature ultraviolet-visible absorption spectroscopy. the results confirm the presence of one trinuclear and one tetranuclear iron-sulfur cluster in both ferredoxins and facilitate comparison of the electronic and magnetic properties of the oxidized and reduced [3 ... | 1987 | 3024733 |
| isolation of a new vanadium-containing nitrogenase from azotobacter vinelandii. | a new nitrogenase from azotobacter vinelandii has been isolated and characterized. it consists of two proteins, one of which is almost identical with the fe protein (component 2) of the conventional enzyme. the second protein (av1'), however, has now been isolated and shown to differ completely from conventional component 1, i.e., the mofe protein. this new protein consists of two polypeptides with a total molecular weight of around 200,000. in place of mo and fe it contains v and fe with a v:fe ... | 1986 | 3026449 |
| on the active sites of the [nife] hydrogenase from desulfovibrio gigas. mössbauer and redox-titration studies. | the [nife] hydrogenase isolated from desulfovibrio gigas was poised at different redox potentials and studied by mössbauer spectroscopy. the data firmly establish that this hydrogenase contains four prosthetic groups: one nickel center, one [3fe-xs], and two [4fe-4s] clusters. in the native enzyme, both the nickel and the [3fe-xs] cluster are epr-active. at low temperature (4.2 k), the [3fe-xs] cluster exhibits a paramagnetic mössbauer spectrum typical for oxidized [3fe-xs] clusters. at higher t ... | 1987 | 3027068 |
| genetic and structural analysis of the rhizobium meliloti fixa, fixb, fixc, and fixx genes. | the fixa, fixb, fixc, and fixx genes of rhizobium meliloti 1021 constitute an operon and are required for nitrogen fixation in alfalfa nodules. dna homologous to the r. meliloti fixabc genes is present in all other rhizobium and bradyrhizobium species examined, but fixabc-homologous sequences were found in only one free-living diazotroph, azotobacter vinelandii. to determine whether the fixabcx genes share sequence homology with any of the 17 klebsiella pneumoniae nif genes, we determined the en ... | 1987 | 3029021 |
| construction of a transposon containing a gene for polygalacturonate trans-eliminase from klebsiella oxytoca. | a dna fragment containing a klebsiella oxytoca gene for polygalacturonate trans-eliminase was cloned into the kanamycin resistance transposon tn5. this new transposon, designated tn5-pga+, had a transposition frequency of 1 x 10(-6). the broad host range plasmid pr751::tn5-pga+ was conjugally transferred to a variety of genetic backgrounds. the ability to degrade polygalacturonate was expressed in aeromonas hydrophila, alcaligenes eutrophus, azotomonas insolita, escherichia coli, pseudomonas put ... | 1987 | 3034186 |
| comparative organization of nitrogen fixation-specific genes from azotobacter vinelandii and klebsiella pneumoniae: dna sequence of the nifusv genes. | in the facultative anaerobe klebsiella pneumoniae 17 nitrogen fixation-specific genes (nif genes) have been identified. homologs to 12 of these genes have now been isolated from the aerobic diazotroph azotobacter vinelandii. comparative studies have indicated that these diverse microorganisms share striking similarities in the genetic organization of their nif genes and in the primary structure of their individual nif gene products. in this study the complete nucleotide sequence of the nifusv ge ... | 1987 | 3040672 |
| aerobic, inactive forms of azotobacter vinelandii hydrogenase: activation kinetics and insensitivity to c2h2 inhibition. | azotobacter vinelandii hydrogenase (ec class 1.12), either purified or membrane-associated, was obtained aerobically in an inactive state. the kinetics of activation by treatment with a reductant (h2 or dithionite) were determined. three distinct phases of the activation were observed. aerobically prepared, inactive hydrogenase was insensitive to acetylene inhibition, but could be rendered acetylene-sensitive by reduction with dithionite. these findings indicate that acetylene inhibition of hydr ... | 1988 | 3052594 |
| bacterial alternative nitrogen fixation systems. | the introduction briefly reviews some of the salient features of the well-characterized conventional molybdo-enzyme system for n2 fixation. this is followed by a brief account of the discovery of an alternative n2 fixation system that does not require molybdenum in the n2-fixing bacterum azotobacter vinelandii. the next section cites observations from the early literature on n2 fixation suggesting may not always require molybdenum. next, recent evidence for an alternative n2 fixation system in a ... | 1988 | 3053048 |
| pseudomonas stutzeri ferredoxin: close similarity to azotobacter vinelandii and pseudomonas ovalis ferredoxins. | the complete primary structure of pseudomonas stutzeri strain zobell ferredoxin was determined by a combination of protease digestion, edman degradation, and carboxypeptidase digestion and was: tfvvtdncikckytdcvevcpvdcfyegpnflvih pdecidcalcepecpaqaifsedevpedqqefielnadlaevwpnite kkdaladaeewdgvkdklqyler. the calculated molecular weight was 12,110 excluding iron and sulfur atoms. the amino acid sequence was highly homologous to those of azotobacter vinelandii and pseudomonas ovalis ferredoxins. it ... | 1988 | 3053681 |
| further analysis of nitrogen fixation (nif) genes in azotobacter chroococcum: identification and expression in klebsiella pneumoniae of nifs, nifv, nifm, and nifb genes and localization of nife/n-, nifu-, nifa- and fixabc-like genes. | the results presented extend previous investigations on the genetics of nitrogen fixation in azotobacter chroococcum and indicate that nif- and fix-like dna is located in at least five different regions of the genome. region i contains functional copies of nifs,v and m, as well as nifh, d and k, all of which complemented mutants of klebsiella pneumoniae. in addition, nife- and/or nifn-like and nifu-like dna is located in this region. the organization of the nif cluster in region i closely resemb ... | 1988 | 3053983 |
| the vanadium-containing nitrogenase of azotobacter. | fifty years after a role of vanadium in biological fixation was proposed, it was shown that in addition to their well-characterized molybdendum nitrogenases, azotobacter chroococcum and azotobacter vinelandii both have a genetically distinct nitrogenase system in which the conventional molybdoprotein is replaced by a vanadoprotein. both mo-nitrogenases and v-nitrogenases have similar requirements for activity: mgatp, a low potential reductant and the absence of oxygen. the genes encoding the v-n ... | 1988 | 3076437 |
| an effective mutagenic method in azotobacter vinelandii. | the acridine-like compound icr-191 is an effective mutagenic agent in azotobacter vinelandii. selectable mutants, such as those resistant to chlorate, can be isolated without post-mutagenic segregation. non selectable mutants, such as those unable to metabolize different sugars, can be easily isolated after twelve generations of post-mutagenic segregation. | 1987 | 3077761 |
| purification to homogeneity of azotobacter vinelandii hydrogenase: a nickel and iron containing alpha beta dimer. | azotobacter vinelandii hydrogenase has been purified to homogeneity from membranes. the enzyme was solubilized with triton x-100 followed by ammonium sulfate-hexane extractions to remove lipids and detergent. the enzyme was then purified by carboxymethyl-sepharose and octyl-sepharose column chromatography. all purification steps were performed under anaerobic conditions in the presence of dithionite and dithiothreitol. the enzyme was purified 143-fold from membranes to a specific activity of 124 ... | 1986 | 3089312 |
| nucleotide sequence analysis of the phosphomannose isomerase gene (pmi) of pseudomonas aeruginosa and comparison with the corresponding escherichia coli gene mana. | phosphomannose isomerase (pmi) has been proposed to catalyze the first step of the alginic acid biosynthetic pathway in pseudomonas aeruginosa. the nucleotide sequence of the p. aeruginosa pmi gene contained on a 2.0-kb bamhi-ssti dna fragment has been determined. the gene was defined by the start and stop codons and by in vitro disruption of an open reading frame of 1440 bp corresponding to a polypeptide product with a predicted mr of 52 860. this polypeptide displayed an apparent mr of approx. ... | 1986 | 3089876 |
| monomer sequence and acetylation pattern in some bacterial alginates. | the sequential structures and acetylation patterns of alginates from several strains of azotobacter vinelandii and pseudomonas species, including p. aeruginosa, p. putida, p. fluorescens, and p. mendocina, have been studied by 1h-n.m.r. spectroscopy. o-acetyl groups were exclusively associated with the d-mannuronic acid residues and the degree of acetylation varied in the range 4-57%, depending upon the proportion of this acid in the polymer. 1h-n.m.r. spectroscopy of a naturally occurring and a ... | 1986 | 3098421 |
| mucoid strains of pseudomonas aeruginosa are devoid of mannuronan c-5 epimerase. | mucoid strains of azotobacter vinelandii, pseudomonas aeruginosa and pseudomonas syringae var glycinia synthesize alginate, an extracellular copolymer comprising d-mannuronosyl and l-guluronosyl moieties. extracellular mannuronan c-5 epimerase, which converts polymannuronate to alginate, was demonstrated in supernatant fluid from cultures of a. vinelandii. however, the enzyme could not be demonstrated, using the same assay, in supernatant fluids of cultures of mucoid strains of p. aeruginosa or ... | 1987 | 3116367 |
| purification of a second alternative nitrogenase from a nifhdk deletion strain of azotobacter vinelandii. | a second alternative nitrogenase complex (nitrogenase 3) was purified from a nifhdk deletion strain of azotobacter vinelandii. the active complex is made up of two components, dinitrogenase 3 and dinitrogenase reductase 3. dinitrogenase 3 contains two protein subunits (alpha, mr 58,000, and beta, mr 50,000) which assemble into at least two active configurations: alpha 2 beta 2 (dinitrogenase 3s) and alpha 1 beta 2 (dinitrogenase 3f). dinitrogenase 3s contains 24 fe and 18 acid-labile s2-ions per ... | 1988 | 3121587 |
| isolation, sequencing, and mutagenesis of the niff gene encoding flavodoxin from azotobacter vinelandii. | the niff gene encoding flavodoxin from azotobacter vinelandii op was cloned and its dna sequence determined. it is located adjacent to, or possibly within, the major nif cluster and it is preceded by nif-specific regulatory elements. southern hybridization analysis revealed that there is only a single copy of the niff gene on the a. vinelandii op genome. mutant strains were constructed which have an insertion mutation or an insertion and a deletion mutation within the niff gene coding sequence. ... | 1988 | 3121629 |
| reconstituted and native iron-cores of bacterioferritin and ferritin. | the structural and magnetic properties of the iron-cores of reconstituted horse spleen ferritin and azotobacter vinelandii bacterioferritin have been investigated by high-resolution transmission electron microscopy, electron diffraction and mossbauer spectroscopy. the structural properties of native horse spleen ferritin, native az. vinelandii, and native and reconstituted pseudomonas aeruginosa bacterioferritins have also been determined. reconstitution in the absence of inorganic phosphate at ... | 1987 | 3123700 |
| examination of protein sequence homologies: iv. twenty-seven bacterial ferredoxins. | sequence homologies of 27 bacterial ferredoxins were examined using a computer program that quantitatively evaluates extent of similarity as a correlation coefficient. the results of a similarity search among the sequences demonstrated that the basal sequence consists of a pair of extremely similar segments of 26 amino acids connected by a three-amino acid group. the segment pairs, which would have arisen from gene duplication, are termed the first and second units. because of the gene duplicati ... | 1987 | 3129571 |
| cloning of nifhd from nostoc commune utex 584 and of a flanking region homologous to part of the azotobacter vinelandii nifu gene. | the heterocystous cyanobacterium nostoc commune utex 584 contains two nifh-like sequences (nifh1 and nifh2) in addition to nifhd. a region of dna 1 kilobase upstream from the 5' end of nifh showed considerable sequence similarity to part of the published nifu sequences of azotobacter vinelandii and klebsiella pneumoniae. | 1988 | 3133363 |
| adp-ribosylation of dinitrogenase reductase from clostridium pasteurianum prevents its inhibition of nitrogenase from azotobacter vinelandii. | the effect of adp-ribosylation of dinitrogenase reductase on its binding to dinitrogenase was investigated. dinitrogenase reductase from clostridium pasteurianum (cp2) was a substrate for the adp-ribosyltransferase and the dinitrogenase-reductase-activating glycohydrolase from rhodospirillum rubrum. adp-ribosylation inactivated cp2 and prevented its formation of a tight complex with dinitrogenase from azotobacter vinelandii (av1). the complex between cp2 and av1 could not be adp-ribosylated once ... | 1988 | 3135803 |
| electron-transfer studies involving flavodoxin and a natural redox partner, the iron protein of nitrogenase. conformational constraints on protein-protein interactions and the kinetics of electron transfer within the protein complex. | the kinetics of electron-transfer reactions involving flavodoxins from klebsiella pneumoniae (kpfld), azotobacter chroococcum (acfld), anacystis nidulans (anfld) and megasphaera elsdenii (mefld), the free, mgadp-bound and mgatp-bound forms of the fe protein component of nitrogenase from k. pneumoniae [kp2, kp2(mgadp)2 and kp2(mgatp)2] and na2s2o4 were studied by stopped-flow spectrophotometry. kinetic evidence was obtained for the formation of binary protein complexes involving kpfldsq (semiquin ... | 1988 | 3140782 |
| purification and properties of dinitrogenase reductase adp-ribosyltransferase from the photosynthetic bacterium rhodospirillum rubrum. | the enzyme that catalyzes the adp-ribosylation and concomitant inactivation of dinitrogenase reductase in rhodospirillum rubrum has been purified greater than 19,000-fold to near homogeneity. we propose dinitrogenase reductase adp-ribosyltransferase (drat) as the working name for the enzyme. drat activity is stabilized by nacl and adp. the enzyme is a monomer with a molecular mass of 30 kda and is a different polypeptide than dinitrogenase reductase activating glycohydrolase. nad (km = 2 mm), et ... | 1988 | 3141411 |
| the vanadium nitrogenase of azotobacter chroococcum. reduction of acetylene and ethylene to ethane. | 1. the vanadium (v-) nitrogenase of azobacter chroococcum transfers up to 7.4% of the electrons used in acetylene (c2h2) reduction for the formation of ethane (c2h6). the apparent km for c2h2 (6 kpa) is the same for either ethylene (c2h4) or ethane (c2h6) formation and much higher than the reported km values for c2h2 reduction to c2h4 by molybdenum (mo-) nitrogenases. reduction of c2h2 in 2h2o yields predominantly [cis-2h2]ethylene. 2. the ratio of electron flux yielding c2h6 to that yielding c2 ... | 1988 | 3162672 |
| levels and activities of nitrogenase proteins in azotobacter vinelandii grown at different dissolved oxygen concentrations. | azotobacter vinelandii was grown diazotrophically at different dissolved oxygen concentrations (in the range of 3 to 216 microm) in sucrose-limited continuous culture. the specific nitrogenase activity, measured on the basis of acetylene reduction in situ, was dependent solely on the growth rate and was largely independent of oxygen and sucrose concentration. femo (av1) and fe (av2) nitrogenase proteins were quantified after western blotting (immunoblotting). when the cultures were grown at a co ... | 1988 | 3162907 |
| the vanadium- and molybdenum-containing nitrogenases of azotobacter chroococcum. comparison of mid-point potentials and kinetics of reduction by sodium dithionite of the iron proteins with bound magnesium adenosine 5'-diphosphate. | the mid-point potentials of the fe protein components (ac2 and ac2* respectively) of the mo nitrogenase and v nitrogenase from azotobacter chroococcum were determined in the presence of mgadp to be -450 mv (nhe) [ac2(mgadp)2-ac2*ox.(mgadp)2 couple] and -463 mv (nhe) [ac2* (mgadp)2-ac2*ox.(adp)2 couple] at 23 degrees c at ph 7.2. these values are consistent with a flavodoxin characterized by deistung & thorneley [(1986) biochem. j. 239, 69-75] with em = -522 mv (nhe) being an effective electron d ... | 1988 | 3164616 |
| time-resolved fluorescence studies on the dihydrolipoyl transacetylase (e2) component of the pyruvate dehydrogenase complex from azotobacter vinelandii. | the dihydrolipoyl transacetylase (e2) component of a. vinelandii pdc and its lipoyl domain shows similar dynamic properties as revealed with fluorescence anisotropy decay of lipoyl-bound iaans. the lipoyl domain (32.6 kda), containing three almost identical subdomains shows a mode of rotation characteristic for a protein of about 30 kda. a similar rotation is found in e2, indicating an independent rotational mobility of the whole domain in the multimeric e2 core (1.6 mda). no independent rotatio ... | 1988 | 3169263 |
| dependence of nitrogenase switch-off upon oxygen stress on the nitrogenase activity in azotobacter vinelandii. | azotobacter vinelandii was grown diazotrophically in chemostat cultures limited by sucrose, citrate, or acetate. specific activities of cellular oxygen consumption (qo2) and nitrogenase (acetylene reduction) were measured in situ at different dilution rates (d, representing the specific growth rate mu at steady state). sucrose-limited cultures exhibited linear relationships between qo2 and d, each of which, however, depended on the dissolved oxygen concentration in the range of 12 to 192 microm ... | 1988 | 3182730 |
| conservation of nif sequences in frankia. | southern blots of frankia total dnas were hybridized with nifhdk probes from rhizobium meliloti, klebsiella pneumoniae and frankia strain arl3. differences between strains were noted in the size of the hybridizing restriction fragments. these differences were more pronounced among elaeagnus-compatible strains than among alnus- or casuarina-compatible strains. gene banks constructed for frankia strains eun1f, hrn18a, ced and acon24d were used to isolate nif-hybridizing restriction fragments for s ... | 1988 | 3185502 |
| mobile sequences in the pyruvate dehydrogenase complex, the e2 component, the catalytic domain and the 2-oxoglutarate dehydrogenase complex of azotobacter vinelandii, as detected by 600 mhz 1h-nmr spectroscopy. | 600 mhz 1h-nmr spectroscopy demonstrates that the pyruvate dehydrogenase complex of azotobacter vinelandii contains regions of the polypeptide chain with intramolecular mobility. this mobility is located in the e2 component and can probably be ascribed to alanine-proline-rich regions that link the lipoyl subdomains to each other as well as to the e1 and e3 binding domain. in the catalytic domain of e2, which is thought to form a compact, rigid core, also conformational flexibility is observed. i ... | 1988 | 3191993 |
| large-scale preparation and reconstitution of apo-flavoproteins with special reference to butyryl-coa dehydrogenase from megasphaera elsdenii. hydrophobic-interaction chromatography. | a new method is described for the large-scale reversible dissociation of flavoproteins into apoprotein and prosthetic group using hydrophobic-interaction chromatography. lipoamide dehydrogenase from azotobacter vinelandii and butyryl-coa dehydrogenase from megasphaera elsdenii are selected to demonstrate the usefulness of the method. in contrast to conventional methods, homogeneous preparations of apoproteins in high yields are obtained. the apoproteins show high reconstitutability. the holoenzy ... | 1988 | 3203689 |
| synthesis of branched-chain sugars: a stereoselective route to sibirosamine, kansosamine, and vinelose from a common precursor. | methyl 4,6-dideoxy-3-c-methyl-4-(n-methyl-n-phenylsulfonylamino)-alpha-l- mannopyranoside and methyl 4-amino-4,6-dideoxy-3-c-methyl-alpha-l-mannopyranoside, derivatives of the branched-chain amino sugars sibirosamine and kansosamine, respectively, were synthesized by nucleophilic ring-opening of methyl 3,4-anhydro-6-deoxy-3-c-methyl-alpha-l-talopyranoside. catalytic reduction of methyl 6-deoxy-2,3-o-isopropylidene-3-c-methyl-alpha-l-lyxo-hexopyrano sid-4-ulose gave the axial alcohol methyl 6-deo ... | 1988 | 3214842 |
| molybdenum and vanadium nitrogenases of azotobacter chroococcum. low temperature favours n2 reduction by vanadium nitrogenase. | a comparison of the effect of temperature on the reduction of n2 by purified molybdenum nitrogenase and vanadium nitrogenase of azotobacter chroococcum showed differences in behaviour. as the assay temperature was lowered from 30 degrees c to 5 degrees c n2 remained an effective substrate for v nitrogenase, but not mo nitrogenase, since the specific activity for n2 reduction by mo nitrogenase decreased 10-fold more than that of v nitrogenase. activity cross-reactions between nitrogenase componen ... | 1988 | 3223922 |
| persistence of captafol in soils with and without amendments and its effects on soil microflora. | | 1988 | 3224173 |
| effect of phorate with and without amendments on soil microflora. | | 1988 | 3224174 |
| characterization of the gene for the fe-protein of the vanadium dependent alternative nitrogenase of azotobacter vinelandii and construction of a tn5 mutant. | a sequence homologous to the conventional nifh gene has been cloned from a different region of the azotobacter vinelandii genome. tn5 insertions were obtained in this clone and the mutagenized plasmid was used for marker exchange with a. vinelandii strain ca12 (delta nifhdk) to obtain tn5 mutants. these mutants exhibited a nif- phenotype in the presence of vanadium, unlike ca12 which was nif+ on vanadium-containing medium. the gene in the cloned nifh-like region is therefore apparently involved ... | 1988 | 3226421 |
| reactivation of inactivated enzyme superoxide dismutase by using the conformation rebuilding method. | we believe that the activities of reactivated and reconstituted enzymes can be completely recovered if optimum conditions of reactivation and reconstitution are found. | 1988 | 3228246 |
| transformation of azotobacter vinelandii op with a broad host range plasmid containing a cloned chromosomal nif-dna marker. | the non-nitrogen-fixing (nif-) strain uw10 of azotobacter vinelandii op (uw) was naturally induced to competence and transformed with broad host range plasmid pkt210 containing the cloned wild-type nif-10 locus from a. vinelandii uw (nif+); this marker was unable to complement the nif-10 mutation in trans, but could through recombination with the chromosome. the most frequent type of transformation event observed was recombination between the homologous regions of the plasmid and chromosome (pro ... | 1988 | 3231689 |
| a rapid, sensitive high-performance liquid chromatography analysis of ammonia and methylamine for nitrogenase assays. | a dansyl chloride precolumn derivatization method has been developed for high-performance liquid chromatography analysis of nh3 and/or ch3nh2 produced by nitrogenase-catalyzed reduction of substrates such as n2 (nh3) or diazirine (nh3, ch3nh2). the dansyl chloride reagent can be used immediately after preparation and is stable at 4 degrees c for 1 month. the derivatization products from nh3 and ch3nh2 are prepared by direct treatment of the assay mixture (30 min of incubation) and are then stabl ... | 1988 | 3239773 |
| polyhydroxybutyrate: an intriguing biopolymer. | the microbial polymer poly-3-hydroxybutyrate (phb) and related poly-hydroxyalkanoates, such as poly-3-hydroxyvalerate and poly-3-hydroxyoctanoate, are unique biodegradable thermoplastics of considerable commercial importance. the structure, properties and regulation of synthesis and degradation of phb are reviewed and the microbial production of copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate, with properties varying according to copolymer composition, is discussed. | 1988 | 3242641 |
| inhibition of nitrogenase by no. | | 1988 | 3255678 |
| effects of alcohols on the reactivity and stability of azotobacter vinelandii hydrogenase. | the effects of alcohols on the reactivity of azotobacter vinelandii hydrogenase were investigated. hydrogenase catalyzed h2 oxidation coupled to methylene blue, benzyl viologen, or phenazine methosulfate when in the presence of solvents containing 15 or 40% ethanol or 40% methanol or 2-propanol. in general, the km's for the electron acceptors were increased substantially by the presence of the alcohols, while the km for h2 was not altered in a solvent containing 40% ethanol. calculation of the a ... | 1988 | 3277540 |
| hydrogen-mediated enhancement of hydrogenase expression in azotobacter vinelandii. | azotobacter vinelandii cultures express more h2 uptake hydrogenase activity when fixing n2 than when provided with fixed n. hydrogen, a product of the nitrogenase reaction, is at least partly responsible for this increase. the addition of h2 to nh4+-grown wild-type cultures caused increased whole-cell h2 uptake activity, methylene blue-dependent h2 uptake activity of membranes, and accumulation of hydrogenase protein (large subunit as detected immunologically) in membranes. both rifampin and chl ... | 1988 | 3280556 |
| [antibiotic activity and heterogeneity of a population of azotobacter chroococcum]. | antibiotic activity of azotobacter chroococcum was determined depending on the morphological composition of the population. the population was divided by the sedimentary properties into 2 fractions: heavy (h) and light (l). a higher amount of azochroomycin (up to 170%) could be extracted from the h-fraction consisting mainly of medium size cells (1.3-1.9 nm in diameter) as compared to that from the l-fraction consisting predominantly of the cells of 0.7-1.3 nm in diameter; the activity of the l- ... | 1988 | 3290885 |
| the dihydrolipoyltransacetylase component of the pyruvate dehydrogenase complex from azotobacter vinelandii. molecular cloning and sequence analysis. | the gene encoding the dihydrolipoyltransacetylase component (e2) of the pyruvate dehydrogenase complex from azotobacter vinelandii has been cloned in escherichia coli. a plasmid containing a 2.8-kbp insert of a. vinelandii chromosomal dna was obtained and its nucleotide sequence determined. the gene comprises 1911 base pairs, 637 codons excluding the initiation codon gug and stop codon uga. it is preceded by the gene encoding the pyruvate dehydrogenase component (e1) of pyruvate dehydrogenase co ... | 1988 | 3292237 |
| identification and characterization of two nitrogen fixation regulatory regions, nifa and nfrx, in azotobacter vinelandii and azotobacter chroococcum. | five tn5-induced nif- mutants of azotobacter vinelandii were characterized as regulatory mutants because they were restored to nif+ by the introduction of constitutively expressed nifa from klebsiella pneumoniae. the mutants fell into two different classes on the basis of hybridization to a rhizobium leguminosarum nifa gene probe and by complementation with cosmids isolated from plafri gene banks of a. vinelandii and azotobacter chroococcum. one mutant, mv3, was located in or near a nifa gene. t ... | 1988 | 3294559 |
| cellular incorporation of poly-beta-hydroxybutyrate into plasma membranes of escherichia coli and azotobacter vinelandii alters native membrane structure. | under growth-limiting conditions or conditions which mediate genetic transformation, escherichia coli and azotobacter vinelandii incorporate poly-beta-hydroxybutyrate into their plasma membranes. genetic transformation competence of both bacteria increased in proportion to the concentration of membrane poly-beta-hydroxybutyrate. the effects of this lipid polymer on membrane structure were investigated by freeze-fracture electron microscopy. before poly-beta-hydroxybutyrate incorporation, freeze- ... | 1987 | 3300913 |
| [results of the storage of freeze dried microbial cultures for 25 years]. | saprophytic microorganisms belonging to different physiological groups (azotobacter, acetic, ammonifying, lactic and nodule bacteria, a phototrophous purple bacterium of the chromatium genus, bacteria of the micrococcus and pseudomonas genera, and a yeast of the candida genus) were stored at 3-6 degrees c for 25 years in the freeze-dried state. all of the strains were found to be viable after the storage. the number of viable cells decreased for some bacteria, but to a far less degree than when ... | 1987 | 3309582 |
| redox-dependent subunit dissociation of azotobacter vinelandii hydrogenase in the presence of sodium dodecyl sulfate. | hydrogenases catalyze the reversible activation of dihydrogen. we have previously demonstrated that the purified hydrogenase from the nitrogen-fixing microorganism azotobacter vinelandii is an alpha beta dimer (98,000 da) with subunits of 67,000 (alpha) and 31,000 (beta) daltons and that this enzyme contains iron and nickel. the enzyme can be purified anaerobically in the presence of dithionite in a fully active state that is irreversibly inactivated by exposure to o2. analysis of this hydrogena ... | 1987 | 3316226 |
| genetics of azotobacters: applications to nitrogen fixation and related aspects of metabolism. | | 1987 | 3318669 |
| sequence of a 1.4 kb eco ri fragment of azotobacter vinelandii nif dna. | | 1988 | 3344210 |
| plasmids of azotobacter vinelandii. | four laboratory strains and two isolates of azotobacter vinelandii were found to contain plasmids. twenty-five laboratory strains which could fix nitrogen did not have free, covalently closed circular plasmid dna. the plasmids varied in size from 9 to 52 megadaltons, and each strain yielded only one plasmid. no discernible differences in ability to fix nitrogen were found between plasmid-bearing and cured cultures. | 1988 | 3350795 |
| hydrogen-mediated mannose uptake in azotobacter vinelandii. | azotobacter vinelandii can grow mixotrophically with h2 plus mannose under n2-fixing conditions (t. y. wong and r. j. maier, j. bacteriol. 163:528-533, 1985). mixotrophically grown cultures incubated in h2 transported mannose with a vmax fourfold greater than that observed for cultures incubated in argon, but h2 did not change the apparent km for mannose. respiratory inhibitors, such as potassium cyanide, hydroxylamine, and p-chloromercuribenzoic acid, as well as the proton conductor carbonyl cy ... | 1988 | 3350796 |
| 7-iron ferredoxin revisited. | the crystal structure of the 7fe ferredoxin from azotobacter vinelandii has been redetermined using area detector data to 2.7-a resolution and a new derivative. tetragonal crystals of the protein were maintained at ph 8.0. the results show that the structure previously reported was in error and confirms a recent independent report of the structure (stout, g.h., turley, s., sieker, l. c., and jensen, l. h. (1988) proc. natl. acad. sci. u. s. a. 85, in press). the protein fold is similar to the ho ... | 1988 | 3379067 |
| revised nucleotide sequence of the azotobacter vinelandii nife gene. | | 1988 | 3387235 |
| pka values of the 8 alpha-imidazole substituents in selected flavoenzymes containing 8 alpha-histidylflavins. | difference absorption spectroscopy as a function of ph is described as a probe to determine the pka values of the 8 alpha-imidazole substituent in flavoenzymes containing 8 alpha-histidylflavin coenzymes. reversible absorption difference spectra are observed in the ph range 5.5 to 8.5 when synthetic 8 alpha-imidazolyl-fmn is bound to the apoflavodoxins from azotobacter vinelandii and from clostridium pasterianum. the observed spectral perturbations of these two flavodoxin complexes follow a sing ... | 1988 | 3395125 |
| cyanamide: a new substrate for nitrogenase. | (1) cyanamide (n identical to c-nh2) has been shown to be a substrate for purified mo-nitrogenases of klebsiella pneumoniae and azotobacter chroococcum, with apparent km values near 0.8 mm. (2) reduction products were ch4, ch3nh2 and nh3 formed by pathways requiring 6 or 8 electrons: n identical to cnh2 + 6e + 6h+----ch3nh2 + nh3; n identical to cnh2 + 8e + 8h+----ch4 + 2nh3 (3) acetylene reduction and hydrogen evolution were inhibited more than 75% by cyanamide (10 mm). cyanamide also inhibited ... | 1988 | 3422164 |
| structure of ferredoxin i from azotobacter vinelandii. | the structure of azotobacter vinelandii ferredoxin i (av fdi, 106 amino acids) has been redetermined, based on x-ray diffraction data from tetragonal crystals of the native protein and two heavy atom derivatives. the current model differs greatly from the one previously reported and is in agreement with arguments based on various spectroscopic and other methods. the unit cell parameters are a = b = 55.62 a and c = 95.51 a, whereas the space group was found to be p4(1)2(1)2 instead of p4(3)2(1)2. ... | 1988 | 3422475 |
| studies on superoxide dismutase. i. purification and properties of superoxide dismutase from azotobacter vinelandii-230. | | 1987 | 3435947 |
| plasmid transformation of azotobacter vinelandii op. | azotobacter vinelandii op which had been naturally induced to competence by growth in iron- and molybdenum-limited medium was transformed with the broad-host-range cloning vector pkt210. however, the transformation frequency at nearly saturating levels of dna was 1000-fold lower for pkt210 than for a single chromosomal dna marker (nif+). plasmid- and chromosomal-dna-mediated transformation events were competitive, magnesium-dependent, 42 degrees c-sensitive processes specific to double-stranded ... | 1987 | 3443852 |