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1.
A. G. McEwan H. G. Wetzstein O. Meyer J. B. Jackson S. J. Ferguson 《Archives of microbiology》1987,147(4):340-345
The periplasmic dissimilatory nitrate reductase from Rhodobacter capsulatus N22DNAR+ has been purified. It comprises a single type of polypeptide chain with subunit molecular weight 90,000 and does not contain heme. Chlorate is not an alternative substrate. A molybdenum cofactor, of the pterin type found in both nitrate reductases and molybdoenzymes from various sources, is present in nitrate reductase from R. capsulatus at an approximate stoichiometry of 1 molecule per polypeptide chain. This is the first report of the occurrence of the cofactor in a periplasmic enzyme. Trimethylamine-N-oxide reductase activity was fractionated by ion exchange chromatography of periplasmic proteins. The fractionated material was active towards dimethylsulphoxide, chlorate and methionine sulphoxide, but not nitrate. A catalytic polypeptide of molecular weight 46,000 was identified by staining for trimethylamine-N-oxide reductase activity after polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The same polypeptide also stained for dimethylsulphoxide reductase activity which indicates that trimethylamine-N-oxide and dimethylsulphoxide share a common reductase.Abbreviations DMSO
dimethylsulphoxide
- LDS
lithium dodecyl sulphate
- MVH
reduced methylviologen
- PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulphate
- TMAO
trimethylamine-N-oxide 相似文献
2.
David J. Richardson Glenn F. King David J. Kelly Alastair G. McEwan Stuart J. Ferguson J. Barry Jackson 《Archives of microbiology》1988,150(2):131-137
Phototrophic growth of Rhodobacter capsulatus (formerly Rhodopseudomonas capsulata) under anaerobic conditions with either butyrate or propionate as carbonsource was dependent on the presence of either CO2 or an auxiliary oxidant. NO
-
3
, N2O, trimethylamine-N-oxide (TMAO) or dimethylsulphoxide (DMSO) were effective provided the appropriate anaerobic respiratory pathway was present. NO
-
3
was reduced extensively to NO
-
3
, TMAO to trimethylamine and DMSO to dimethylsulphide under these conditions. Analysis of culture fluids by nuclear magnetic resonance showed that two moles of TMAO or DMSO were reduced per mole of butyrate utilized and one mole of either oxidant was reduced per mole of propionate consumed. The growth rate of Rb. capsulatus on succinate or malate as carbon source was enhanced by TMAO in cultures at low light intensity but not at high light intensities. A new function for anaerobic respiration during photosynthesis is proposed: it permits reducing equivalents from reduced substrates to pass to auxiliary oxidants present in the medium. The use of CO2 or auxiliary oxidants under phototrophic conditions may be influence by the availability of energy from light. It is suggested that the nuclear magnetic resonance methodology developed could have further applications in studies of bacterial physiology.Abbreviations DMS
dimethylsulphide
- DMSO
dimethylsulphoxide
- TMA
trimethylamine
- TMAO
trimethylamine-N-oxide
- NMR
nuclear magnetic resonance 相似文献
3.
D. J. Kelly D. J. Richardson S. J. Ferguson J. B. Jackson 《Archives of microbiology》1988,150(2):138-144
1) Rhodobacter capsulatus (formerly Rhodopseudomonas capsulata) strain 37b4 was subjected to transposon Tn5 mutagenesis. 2) Kanamycin-resistant transconjugants were screened for their inability to reduce trimethylamine-N-oxide (TMAO) as judged by the lack of alkali production during anaerobic growth on plates containing glucose as carbon source and cresol red as pH indicator. 3) Of 6 mutants examined, all were found to have considerably decreased levels of methylviologen-dependent TMAO reductase activity and dimethylsulphoxide (DMSO) reductase activity. 4) Periplasmic fractions of one of these mutants (DK9) and of the parent strain were subjected to sodium dodecylsulphate polyacrylamide gel electrophoresis. The gels were stained for TMAO-reductase and DMSO-reductase. With the wild-type strain, only a single polypeptide band, Mr=46,000, stained for TMAO and DMSO reductase activity. In mutant DK9 this band was not detectable. 5) In contrast to the parent strain, harvested washed cells of mutant DK9 were unable to generate a cytoplasmic membrane potential in the presence of TMAO or DMSO under dark anaerobic conditions. 6) In contrast to the parent strain, DK9 was unable to grow in dark anaerobic culture with fructose as the carbon source and TMAO as oxidant.Abbreviations TMAO
trimethylamine-N-oxide
- DMSO
dimethylsulphoxide
- PMS
phenazine methosulphate
-
cytoplasmic membrane potential 相似文献
4.
Hyphomicrobium EG can grow with dimethylsulphoxide as sole carbon and energy source with oxygen as electron acceptor. In the present work we have found that the dimethylsulphoxide reductase of this bacterium could be assayed with dithionite-reduced methylviologen as reductant but not with NADH. Sub-cellular fractionation of Hyphomicrobium EG showed that the dimethylsulphoxide reductase was a periplasmic enzyme. An antibody to the dimethylsulphoxide reductase of Rhodobacter capsulatus cross-reacted with a polypeptide in the periplasmic fraction from Hyphomicrobium EG which had the same M
r as the dimethylsulphoxide reductase of Rhodobacter capsulatus. It is suggested that the reduction of dimethylsulphoxide in Hyphomicrobium involves respiratory electron transfer.Abbreviations
DMSO
dimethylsulphoxide
-
DMS
dimethylsulphide 相似文献
5.
D. J. Richardson D. J. Kelly J. B. Jackson S. J. Ferguson K. Alef 《Archives of microbiology》1986,146(2):159-165
The effects of various electron transport inhibitors upon the rates of reduction NO
3
-
, dimethyl sulphoxide (DMSO) and N2O in anaerobic suspensions of Rhodobacter capsulatus have been studied. A new method for the determination of the rates of reduction of these auxiliary oxidants in intact cells is presented, based on the proportionality observed between the concentration of oxidant and the duration of the electrochromic carotenoid bandshift. For NO
3
-
and N2O good agreement was found between rates of reduction determined using electrodes and those determined by the electrochromic method.Myxothiazol and antimycin A had no effect on the rates of reduction of NO
3
-
and DMSO suggesting that the cytochrome b/c
1complex is not involved in electron transport to these oxidants. 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO) inhibited at two sites, one within the cytochrome b/c
1complex and the other on the nitrate reducing pathay, but had no effect on electron transport to N2O or DMSO. In both intact cells and cell free extracts, HOQNO had no effect on the nitrate dependent re-oxidation of reduced methylviologen (MVH2), a direct electron donor to nitrate reductase.Our data are consistent with a branch point for the auxiliary electron transport pathways at the level of the ubiquinone pool.Non-standard abbreviations HOQNO
2-n-heptyl-4-hydroxyquinoline-N-oxide
- TMAO
trimethylamine-N-oxide
- DMSO
dimethyl-sulphoxide
-
membrane potential
- MVH2
reduced methyl viologen 相似文献
6.
Chemolithotrophic potential of a Hyphomicrobium species,capable of growth on methylated sulphur compounds 总被引:1,自引:0,他引:1
The yield of Hyphomicrobium EG on dimethyl sulphoxide, dimethyl sulphide and methylamine, considering the metabolic pathways of these compounds, suggested that the organism gained energy from the oxidation of the sulphur moiety of the former compounds. Indeed, a comparison of chemostat cultures of Hyphomicrobium EG grown on methylamine in the presence and absence of sulphide or thiosulphate proved this obligate methylotroph to be a chemolithoheterotroph. The apparent Ysulphide and Ythiosulphate were comparable, being 8–10 g dry weight/mol. In batch cultures thiosulphate concentrations up to 10 mM had a stimulatory effect on the growth rate of Hyphomicrobium EG, whereas higher concentrations increased the organisms doubling time.Enzyme- and respiration data showed that the organism had constitutive enzymes for the breakdown of dimethyl sulphoxide although they were clearly regulated to need. Addition of sulphide or thiosulphate to methylamine-limited chemostat cultures of Hyphomicrobium EG not only resulted in the induction of enzymes necessary for their breakdown, but also caused the enzymes for dimethyl sulphoxide metabolism, especially methyl mercaptan oxidase, to be induced. The formation of H2O2, a product of the latter enzyme, was reflected in the relatively high catalase activities during growth on dimethyl sulphoxide and in the organisms inability to grow on this compound in the presence of a catalase inhibitor.Abbreviations DMSO
dimethyl sulphoxide
- DMS
dimethyl sulphide
- MM
methyl mercaptan
- TMAO
trimethylamine N-oxide
- D
dilution rate
- GSH
redticed glutathione
- DCPIP
2,6-dichlorophenolindophenol
- PMS
phenazine methosulphate
- PES
phenazine ethosulphate
- RubPCase
ribulose 1,5-bisphosphate carboxylase
- PEPCase
phosphoenol pyruvate carboxylase
- Wurster's blue (TMPD)
N,N,N,N-tetramethyl-p-phenylenediamine 相似文献
7.
In order to distinguish between the regulatory effects of oxygen tension and light intensity on cytochrome c oxidase protein and enzymatic activity cells of Rhodobacter capsulatus were shifted from phototrophic (anaerobic, light) growth to aerobic-light, aerobic-dark and to anaerobic-dark conditions, respectively. During shift-experiments the formation of oxidase protein and regulation of oxidase activity was followed by immunological and enzymatic means. The results support the idea, that the formation of oxidase protein is regulated by oxygen tension and light intensity changes, whereas the regulation of oxidase activity seems only to be correlated to the oxygen tension. A DNA sequence involved in the oxygen-dependent regulation of cytochrome oxidase could be identified in the regulation-deficient oxidase mutant H41 of R. capsulatus. Immunological investigations of cytochrome c
2 from mutant H41 demonstrated at the same time the participation of the c
2-polypeptide in the regulation of cytochrome c oxidase.Abbreviations Bchl
bacteriochlorophyll
- CIE
crossed immuno-electrophoresis
- DMSO
dimethyl sulfoxide 相似文献
8.
Chlorate and nitrate reduction in the phototrophic bacteriaRhodobacter capsulatus andRhodobacter sphaeroides 总被引:1,自引:0,他引:1
Chlorate or trimethylamine-N-oxide (TMAO) added to phototrophic cultures ofRhodobacter sphaeroides DSM 158 increased both the growth rate and the growth yield although this stimulation was not observed in the presence of tungstate. This strain, exhibited basal activities of nitrate, chlorate, and TMAO reductases independently of the presence of these substrates in the culture medium, and nitrate reductase (NR) activity was competitively inhibited by chlorate. Phototrophic growth ofRhodobacter capsulatus B10, a strain devoid of NR activity, was inhibited only by 100 mM chlorate. However, growth of the nitrate-assimilatingR. capsulatus strains E1F1 and AD2 was sensitive to 10mm chlorate, and their NR activities were not inhibited by chlorate. Both NR and chlorate reductase (CR) activities of strain E1F1 were induced in the presence of nitrate or chlorate respectively, whereas strain AD2 showed basal levels of these activities in the absence of the substrates. A basal TMAO reductase (TR) activity was also observed when these strains ofR. capsulatus were cultured in the absence of this electron acceptor. These results suggest that chlorate and TMAO can be used as ancillary oxidants byRhodobacter strains and that a single enzyme could be responsible for nitrate and chlorate reduction inR. sphaeroides DSM 158, whereas these reactions are catalyzed by two different enzymes inR. capsulatus E1F1 and AD2. 相似文献
9.
Ammonia oxidation by the methane oxidising bacterium Methylococcus capsulatus strain bath 总被引:1,自引:0,他引:1
Soluble extracts of Methylococcus capsulatus (Bath) that readily oxidise methane to methanol will also oxidise ammonia to nitrite via hydroxylamine. The ammonia oxidising activity requires O2, NADH and is readily inhibited by methane and specific inhibitors of methane mono-oxygenase activity. Hydroxylamine is oxidised to nitrite via an enzyme system that uses phenazine methosulphate (PMS) as an electron acceptor. The estimated K
mvalue for the ammonia hydroxylase activity was 87 mM but the kinetics of the oxidation were complex and may involve negative cooperativity.Abbreviations PMS
Phenazine methosulphate
- NADH
nicotinamide adenine dinucleotide, reduced form
-
K
m
Michaelis constant
- NO
2
-
nitrite
- NH2OH
hydroxylamine 相似文献
10.
Yosepha Shahak Christof Klughammer Ulrich Schreiber Etana Padan Inge Herrman Günter Hauska 《Photosynthesis research》1994,39(2):175-181
The reduction by sulfide of exogenous ubiquinone is compared to the reduction of cytochromes in chromatophores of Rhodobacter capsulatus. From titrations with sulfide values for Vmax of 300 and 10 moles reduced/mg bacteriochlorophyll a·h, and for Km of 5 and 3 M were estimated, for decyl-ubiquinone-and cytochrome c-reduction, respectively. Both reactions are sensitive to KCN, as has been found for sulfide-quinone reductase (SQR) in Oscillatoria limnetica, which is a flavoprotein. Effects of inhibitors interfering with quinone binding sites suggest that at least part of the electron transport from sulfide in R. capsulatus employs the cytochrome bc
1-complex via the ubiquinone pool.Abbreviations BChl a
bacteriochlorophyll a
- DAD
diaminodurene
- decyl-UQ
decyl-ubiquinone
- LED
light emitting diode
- NQNO
2-n-nonyl-4-hydroxyquinoline-N-oxide
- PQ-1
plastoquinone 1
- SQR
sulfide-quinone reductase (E.C. 1.8.5.'.)
- UQ
ubiquinone 10
- Qc
the quinone reduction site on the cytochrome b
6
f/bc
1, complex (also termed Qi or Qr or Qn)
- Qs
the quinone reduction site on SQR
- Qz
quinol oxidation site on the b
6
f/bc
1, complex (also termed Qo or Qp) 相似文献
11.
Cloning and sequencing of the genes encoding the large and the small subunits of the H2 uptake hydrogenase (hup) of Rhodobacter capsulatus 总被引:12,自引:0,他引:12
Michèle Leclerc Annette Colbeau Béatrice Cauvin Paulette M. Vignais 《Molecular & general genetics : MGG》1988,214(1):97-107
Summary The structural genes (hup) of the H2 uptake hydrogenase of Rhodobacter capsulatus were isolated from a cosmid gene library of R. capsulatus DNA by hybridization with the structural genes of the H2 uptake hydrogenase of Bradyrhizobium japonicum. The R. capsulatus genes were localized on a 3.5 kb HindIII fragment. The fragment, cloned onto plasmid pAC76, restored hydrogenase activity and autotrophic growth of the R. capsulatus mutant JP91, deficient in hydrogenase activity (Hup-). The nucleotide sequence, determined by the dideoxy chain termination method, revealed the presence of two open reading frames. The gene encoding the large subunit of hydrogenase (hupL) was identified from the size of its protein product (68108 dalton) and by alignment with the NH2 amino acid protein sequence determined by Edman degradation. Upstream and separated from the large subunit by only three nucleotides was a gene encoding a 34 256 dalton polypeptide. Its amino acid sequence showed 80% identity with the small subunit of the hydrogenase of B. japonicum. The gene was identified as the structural gene of the small subunit of R. capsulatus hydrogenase (hupS). The R. capsulatus hydrogenase also showed homology, but to a lesser extent, with the hydrogenase of Desulfovibrio baculatus and D. gigas. In the R. capsulatus hydrogenase the Cys residues, (13 in the small subunit and 12 in the large subunit) were not arranged in the typical configuration found in [4Fe–4S] ferredoxins. 相似文献
12.
The ammonium uptake system of Rhodobacter capsulatus B100 was examined using the ammonium analog methylammonium. This analog was not transported when cells were grown aerobically on ammonium. When cultured on glutamate as a nitrogen source, or when nitrogen-starved, cells would take up methylammonium. Therefore, in cells grown under nitrogen-limiting conditions, a second system of ammonium uptake (or a modified form of the first) is present which is distinguished by its capacity for transporting the analog in addition to ammonium. The methylammonium uptake system exhibited saturation kinetics with a K
m of 22 M and a V
max of about 3 nmol per min · mg protein. Ammonium completely inhibited analog transport with a K
i in the range of 1 M. Once inside the cell methylammonium was rapidly converted to -N-methylglutamine; however, a small concentration gradient of methylammonium could still be observed. Kinetic parameters reflect the effects of assimilation.The methylammonium uptake system was temperature and pH dependent, and inhibition studies indicated that energy was required for the system to be operative. A glutamine auxotroph (G29) lacking the structural gene for glutanime synthetase did not accumulate the analog, even when nitrogen starved. The Nif- mutant J61, which is unable to express nitrogenase structural genes, also did not transport methylammonium, regardless of the nitrogen source for growth. However, the mutant exhibited wild-type ammonium uptake and glutamine synthetase activity. These data suggest that transport of ammonium is required for growth on limited nitrogen and is under the control of the Ntr system in R. capsulatus.Abbreviations CCCP
carbonyl cyanide-m-chlorophenyl hydrazone
- CHES
cyclohexylaminoethanesulfonic acid
- DMSO
dimethyl sulfoxide
- GMAD
-N-methylglutamine
- GS
glutamine synthetase
- MES
2-(N-morpholino) ethanesulfonic acid
- MSX
methionine-Dl-sulfoximine
- pCMB
p-chloromercuribenzoate
- Tricine
N-tris(hydroxymethyl)methylglycine 相似文献
13.
J. Oelze 《Plant and Soil》1991,137(1):135-138
The question, whetherAzotobacter vinelandii can provide fixed N for the growth of other organisms, was studied with mixed cultures ofA. vinelandii andRhodobacter capsulatus, grown with aeration in the light. N2-fixation byR. capsulatus was prevented by growing the cultures on either mannitol, glycerol or ethanol, which cannot be used by this organism. In the course of growth with mannitol, cell numbers of both organisms increased largely in parallel and attained a maximal ratio of about oneA. vinelandii per tenR. capsulatus. Prolonged growth of mixed cultures with mannitol did not lead to an adaptation ofR. capsulatus to this compound. After growth on either one of the three alcohols, mixed cultures exhibited almost twice as high protein levels as pure cultures ofA. vinelandii. Up to 80% of the protein of mixed cultures was incorporated intoR. capsulatus. The results suggest thatA. vinelandii provided an organic N-source for the growth ofR. capsulatus. 相似文献
14.
G. J. Morris 《Archives of microbiology》1976,107(1):57-62
The cryoprotective additives glycerol and dimethylsulphoxide were found to be toxic to Chlorella cells at concentrations greater then 2.5% w/v. Polyvinylpyrrolidone, was not damaging up to a concentration of 15% w/v.
Chlorella 211/7a had a recovery rate greater than 95% at all rates of cooling studied. With Chlorella 211/8h the survival was lower than 0.1% at all rates examined. The addition of dimethylsulphoxide (5% w/v) to Chlorella 211/8h increased the recovery, particularly at the faster rates of cooling; with polyvinylpyrrolidone (10% w/v) there was an optimum range of cooling rate.Cells of Chlorella 211/7a from the exponential phase of growth were found to be damaged both by a temperature reduction from 25°C to 0°C (thermal shock) and by freezing and thawing. In contrast cells from the stationary phase of growth were resistant to these stresses.Abbreviations DMSO
dimethylsulphoxide
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethansulphonic acid
- PVP
polyvinylpyrrolidone 相似文献
15.
The characteristics of malate transport into aerobically grown cells of the purple photosynthetic bacterium Rhodobacter capsulatus were determined. A single transport system was distinguished kinetically which displayed a Kt value of 2.9 ± 1.2 μM and Vmax of 43 ± 6 nmol · min-1 · mg-1 protein. Competition experiments indicated that the metabolically related C4-dicarboxylates succinate and fumarate are also
transported by this system. Malate uptake was sensitive to osmotic shock and evidence from the binding of radiolabelled malate
and succinate to periplasmic protein fractions indicated that transport is mediated by a dicarboxylate binding protein. The
activity of the transport system was studied as a function of external and internal pH and it was found that a marked activation
of uptake occurred at intracellular pH values greater than 7. The use of a high affinity binding protein dependent system
to transport a major carbon and energy source suggests that Rhodobacter capsulatus would be capable of obtaining growth sustaining quantities of C4-dicarboxylates even if these were present at very low concentrations
in the environment. 相似文献
16.
Javier G. Fernández-Velasco Silvia Cocchi Mauro Neri Günter Hauska B. Andrea Melandri 《Journal of bioenergetics and biomembranes》1991,23(2):365-379
The cytochromebc
1 complexes from the nonphotosynthetic strain R126 ofRhodobacter capsulatus and from its revertant MR126 were purified. Between both preparations, no difference could be observed in the stoichiometries of the cytochromes, in their spectral properties, and in their midpoint redox potentials. Both also showed identical polypeptide patterns after electrophoresis on polyacrylamide gels in the presence of sodium dodecylsulfate. The ubiquinol: cytochromec oxidoreductase activity was strongly inhibited in the complex from the mutant compared to the one from the revertant. So was the oxidant-induced extra reduction of cytochromeb. Both preparations, however, showed an antimycin-induced red shift of cytochromeb, as well as antimycin-sensitive reduction of cytochromeb by ubiquinol. In accordance with a preceding study of chromatophores (Robertsonet al. (1986).J. Biol. Chem.
261, 584–591), it is concluded that the mutation affects specifically the ubiquinol oxidizing site, leaving the ubiquinol reducing site unchanged. 相似文献
17.
A. Wessing G. Bertram K. Zierold 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(6):452-462
The intracellular distribution of potassium in Malpighian tubules from Drosophila larva was measured by electron probe X-ray microanalysis of freeze-dried cryosections. Application of amiloride alone to the haemolymph space had no effect on the intracellular potassium concentration in the region of intermediate cytoplasm (between the basal region of basal membrane infoldings and the apical brush border), whereas a potassium increase as well as a chloride increase was observed after simultaneous blocking of the potassium conductance of the basal membrane with barium. Injected bafilomycin and amiloride applied in the haemolymph caused an increase of the potassium content in the basal cytoplasm but not in the microvilli. In addition, the intracellular water portion was decreased by bafilomycin. pH measurements in isolated larval anterior tubules with proton-selective microelectrodes showed that bafilomycin added to the bathing solution caused a decrease in intracellular pH. Addition of amiloride had no significant effect on intracellular pH, but the pH of the luminal fluid was decreased within 1 min by 0.5 pH units. The amiloride-induced luminal pH decrease could be inhibited by the metabolic blocker KCN as well as by bafilomycin. Furthermore, removing potassium from the bathing saline caused a slow luminal acidification, which could be blocked by KCN. Our results support the hypothesis of a functionally coupled transport system in the apical membrane consisting of a bafilomycin-sensitive V-ATPase and a K+-dependent, amiloride-sensitive K+/H+ exchange system.Abbreviation
C
a
element concentration related to water
-
C
d
element content related to dry weight
- dw
dry weight
- DMSO
dimethylsulphoxide
- emf
electromotive force
- NBD-Cl
7-chloro-4-nitrobenz-2-oxa-1,3-diazole
- NEM
N-ethylmaleimide
- NMDG+
N-methyl-d-glucamine
- PD
potential difference
- pHi
intracellular pH value
- pHlu
luminal pH value
- pmf
protonmotive force
- SD
standard deviation
- SE
standard error
- STEM
scanning transmission electron microscopy
-
V
a
apical potential difference
-
V
b
basal potential difference
-
V
t
transepithelial potential difference 相似文献
18.
Inhibition studies of methane mono-oxygenase activity in whole cell suspensions of Methylococcus capsulatus (Texas) and M. capsulatus (Bath) were performed and the results compared. The inhibition pattern for M. capsulatus (Bath) was not only substantially different from the pattern obtained with M. capsulatus (Texas) but also very limited in the number of potent inhibitors specific for methane oxidation. To confirm the whole cell results of M. capsulatus (Bath) similar experiments were done using cell-free extracts. It was found that only acetylene (100% inhibition) and 8-hydroxyquinoline (71%) significantly inhibited methane oxidation, verifying the restricted inhibition pattern found with the whole cell suspensions. Eight acetylenic compounds were tested for specific inhibition of methane oxidation by whole cells and cell-free extracts of M. capsulatus (Bath). Only two compounds (acetylene and propyne) gave 100% inhibition in both cases with three other compounds (but-1-yne, but-2-yne and propyn-1-ol) giving weaker inhibitions. The inhibition pattern of methane oxidation by whole cell suspensions and cell-free extracts of M. capsulatus (Bath) is discussed and reasons for the prominent results are suggested. 相似文献
19.
High levels of aconitase and fumarase activities were found in Rhodobacter capsulatus E1F1 cells cultured with nitrate as the sole nitrogen source either under light-anaerobic or dark-aerobic conditions. Both activities were strongly and reversibly inhibited in vitro by nitrite or nitric oxide, whereas nitrate or hydroxylamine showed a lower effect. Other enzymes of the tricarboxylic acids cycle such as malate dehydrogenase or isocitrate dehydrogenase were not affected by these nitrogen compounds. When growing on nitrate in the dark R. capsulatus E1F1 cells accumulated nitrite intracellularly, so that an in vivo inhibition of aconitase and fumarase could account for the strong inhibition of growth observed in the presence of nitrite under dark-aerobic conditions.Abbreviations ACO
aconitase
- FUM
fumarase
- MDH
malate dehydrogenase
- ICDH
isocitrate dehydrogenase
- TCA
tricarboxylic acid 相似文献
20.
E. Bräutigam F. Fiedler D. Woitzik H. T. Flammann J. Weckesser 《Archives of microbiology》1988,150(6):567-573
The capsule polysaccharide-protein-peptidoglycan complex (insoluble in boiling sodium dodecyl sulfate and hot phenol-water) from cell envelopes of Rhodobacter capsulatus St. Louis was characterized. Hydrofluoric, hydrochloric acid or alkaline hydrolysis solubilized the polysaccharide moiety, whereas the protein-peptidoglycan moiety remained insoluble. On treatment of the protein-peptidoglycan moiety with lysozyme, the protein with peptidoglycan-residues bound was solubilized. It showed a single, broad peptide band (M
r=about 17,000) on sodium dodecyl sulfate polyacrylamide gel-electrophoresis. The same protein was obtained by lysozyme digestion (without preceding hydrofluoric or hydrochloric acid treatment) of the protein-peptidoglycan complex of the phage-resistant mutant Rhodobacter capsulatus St. Louis RC1-, in which the capsule polysaccharide is present in a free form. A protein-peptidoglycan complex was isolated also from the capsulefree Rhodobacter capsulatus 37b4. Covalent binding between the protein and peptidoglycan moieties is likely for all three strains as is the lipoprotein nature of the protein moiety. The polysaccharide moiety of the complete complex from the wild-type Rhodobacter capsulatus St. Louis was at least partly removable from the complex in the presence of high salt concentrations or ethylene diamine tetraacetate. A specific amino acid pattern (with Ser, Gly, Glu, and Ala dominating) remained constantly associated with the capsule polysaccharide moiety independent of the separation procedure.Abbreviations A2pm
diaminopimelic acid
- Cetavlon
cetyltrimethyl-ammonium bromide
- EDTA
ethylene-diaminetetraacetate, disodium salt
- HF
hydrofluoric acid
- HPLC
high-performance liquid chromatography
- PAGL
polyacrylamide gel-electrophoresis
- SDS
sodium dodecyl sulfate
- TCA
trichloroacetic acid 相似文献