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排序方式: 共有393条查询结果,搜索用时 15 毫秒
1.
A strain of Methylomonas albus BG8WM, a type 1 obligate methanotroph, which had been maintained for 2 ycars by serial passage on solid medium containing methanol as a carbon source was found to mutate at a frequency of 10-5-10-6 to resistance to dichloromethane (DCMR), the parental strain BG8 did not give rise to DCMR colonies. DCMR strains were no longer capable of growth on methane as a carbon cource and exhibited greatly reduced or undetectable methane mono-oxygenase activity. The mutants fell into three groups on the basis of SDS-PAGE analysis of the polypeptide profiles of the particulate fraction of cell extracts. One or more of four polypeptides of Mr 70,000, 50,000, 25,000 and 23,000 were implicated as being components of the methane mono-oxygenase. Spontaneous reversion to growth on methane and sensitivity to dichloromethane occurred at a frequency of about 10-8. The loss of methane mono-oxygenase activity was not associated with loss of the resident 55 kb plasmid.Abbreviations DCMR
dichloromethane-resistant
- SDS-PAGE
sodium dodecyl sulphate polyacrylamide gel electrophoresis
- NMS
nitrate minimal salts medium 相似文献
2.
The genes encoding the six polypeptide components of the alkene monooxygenase from Xanthobacter Py2 have been sequenced. The predicted amino acid sequence of the first ORF shows homology with the iron binding subunits of binuclear non-haem iron containing monooxygenases including benzene monooxygenase, toluene 4-monooxygenase (>60% sequence similarity) and methane monooxygenase (>40% sequence similarity) and that the necessary sequence motifs associated with iron co-ordination are also present. Secondary structure prediction based on the amino acid sequence showed that the predominantly α-helical structure that surrounds the binuclear iron binding site was conserved allowing the sequence to be modelled on the co-ordinates of the methane monooxygenase α-subunit. Significant differences in the residues forming the hydrophobic cavity which forms the substrate binding site are discussed with reference to the differences in reaction specificity and stereospecificity of binuclear non-haem iron monooxygenases. 相似文献
3.
Y. Jiang 《Biochimica et Biophysica Acta (BBA)/General Subjects》1994,1201(1):76-84
Proteolysis of the hydroxylase component of soluble methane monooxygenase (MMO) with trypsin yielded a protein which retained 50% activity in a standard MMO assay. In an H2O2-driven assay, in which H2O2 replaced two of the protein components, NADH and O2 used in the standard assay, the proteolysed hydroxylase retained full activity for ethane, propane and propene, but had a 2–3 fold increase with methane as substrate. Several crosslinking reagents have been tested for their ability to stabilise the proteolysed form of the hydroxylase. Using polyoxyethylene bis(imidazolyl carbonyl) (Mr 3350) as the crosslinking agent, increased thermostability of the hydroxylase was observed. Activated methoxypolyethylene glycol (Mr 5000) was used to modify the hydroxylase which was now soluble in organic solvents as well as water and could be activated by H2O2. The glycol-modified hydroxylase functioned well in organic solvents in the catalysis of propene oxidation. 相似文献
4.
C. L. Keith R. L. Bridges L. R. Fina K. L. Iverson J. A. Cloran 《Archives of microbiology》1978,118(2):169-172
Anaerobic rupture of the benzoic acid ring was investigated. Carbon 4 was converted primarily to carbon dioxide. Following ring rupture during methane fermentation, propanoic acid is an intermediate, and carbon 4 of benzoate becomes its carboxyl.Contribution No. 1285-j, Division of Biology, Kansas State University, Manhattan, KS 66506. This work was supported in part by funds from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS 66506. Paper II of this series is Fina and Fiskin (1960) 相似文献
5.
Andrew C. Stainthorpe J. Colin Murrell George P. C. Salmond Howard Dalton Veronica Lees 《Archives of microbiology》1989,152(2):154-159
Methane monooxygenase (MMO) is the enzyme responsible for the conversion of methane to methanol in methanotrophic bacteria. In addition, this enzyme complex oxidizes a wide range of aliphatic and aromatic compounds in a number of potentially useful biotransformations. In this study, we have used biochemical data obtained from purification and characterization of the soluble MMO from Methylococcus capsulatus (Bath), to identify structural genes encoding this enzyme by oligonucleotide probing. The genes encoding the and subunits of MMO were found to be chromosomally located and were linked in this organism. We report here on the analysis of a recombinant plasmid containing 12 kilobases of Methylococcus DNA and provide the first evidence for the localization and linkage of genes encoding the methane monooxygenase enzyme complex. DNA sequence analysis suggests that the primary structures of the and subunit of MMO are completely novel and the complete sequence of these genes is presented. 相似文献
6.
Purification and some properties of the methyl-CoM reductase of Methanothrix soehngenii 总被引:1,自引:0,他引:1
Mike S.M. Jetten Alfons J.M. Stams Alexander J.B. Zehnder 《FEMS microbiology letters》1990,66(1-3):183-186
Abstract The methyl-CoM reductase from Methanothrix soehngenii was purified 18-fold to apparent homogeneity with 50% recovery in three steps. The native molecular mass of the enzyme estimated by gel-fitration was 280 kDa. SDS-polyacrylamide gel electrophoresis revealed three protein bands corresponding to M r 63 900, 41 700 and 30 400 Da. The methyl-coenzyme M reductase constitutes up to 10% of the soluble cell protein. The enzyme has K m apparent values of 23 μM and 2 mM for N -7-mercaptoheptanoylthreonine phosphate (HS- HTP = component B ) and methyl-coenzyme M (CH3 CoM) respectively. At the optimum pH of 7.0 60 nmol of methane were formed per min per mg protein. 相似文献
7.
From dilution series in defined mineral medium, a marine iregular coccoid methanogenic bacterium (strain MTP4) was isolated
that was able to grow on methanethiol as sole source of energy. The strain also grew on dimethylsulfide, mono-, di-, and trimethylamine,
methanol and acetate. On formate the organism produced methane without significant growth. Optimal growth on MT, with doubling
times of about 20 h, occurred at 30°C in marine medium. The isolate required p-aminobenzoate and a further not identified
vitamin. Strain MTP4 had a high tolerance to hydrogen sulfide but was very sensitive to mechanical forces or addition of detergents
such as Triton X-100 or sodium dodecylsulfate. Methanethiol was fermented by strain MTP4 according to the following equation:
相似文献
8.
9.
Some rumen ciliates have endosymbiotic methanogens 总被引:16,自引:0,他引:16
Bland J. Finlay Genoveva Esteban Ken J. Clarke Alan G. Williams T.Martin Embley Robert P. Hirt 《FEMS microbiology letters》1994,117(2):157-161
Abstract Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F
10.
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