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11.
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
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Nakamura T Hoaki T Hanada S Maruyama A Kamagata Y Fuse H 《FEMS microbiology letters》2007,277(2):157-164
Soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO) gene clusters in the marine methanotroph Methylomicrobium sp. strain NI were completely sequenced and analysed. Degenerated primers were newly designed and used to amplify the gene fragments containing intergenic mmoX-Y and mmoD-C regions and a partial pmoC region. Phylogenetic analysis of amino acid sequences deduced from mmoX and pmoA, as well as of 16S rRNA gene sequences, indicated that this strain was most closely related to the halotolerant methanotroph Methylomicrobium buryatense. There were putative sigma(54)- and sigma(70)-dependent promoter sequences upstream of the sMMO and pMMO genes, respectively, and mmoG, which is known to be related to the expression and assembly of sMMO, existed downstream of the sMMO genes. These findings suggest that the major components and regulation of MMOs in this marine methanotroph are quite similar to those in freshwater methane oxidizers, despite the difference in their habitats. 相似文献
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Bhattacharjee P. Shukla V.B. Singhal R.S. Kulkarni P.R. 《World journal of microbiology & biotechnology》2001,17(8):811-816
Fermentative production of squalene under anaerobic conditions using commercially available compressed baker's yeast (Saccharomyces cerevisiae), and a strain of Torulaspora delbrueckii isolated from molasses was studied. Yield of squalene from S. cerevisiae and T. delbrueckii were found to be 41.16 and 237.25 g g–1 respectively, dry weight of yeast cells. Isolation and purification of squalene from the lipid extracts obtained by cell lysis of either strain were achieved chromatographically. The purified squalene was characterized spectroscopically against an authentic standard. 相似文献
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Sorgoleone 总被引:2,自引:0,他引:2
Franck E. Dayan Agnes M. Rimando Scott R. Baerson Stephen O. Duke 《Phytochemistry》2010,71(10):1032-306
Sorgoleone, a major component of the hydrophobic root exudate of sorghum [Sorghum bicolor (L.) Moench], is one of the most studied allelochemicals. The exudate also contains an equivalent amount of a lipid resorcinol analog as well as a number of minor sorgoleone congeners. Synthesis of sorgoleone is constitutive and compartmentalized within root hairs, which can accumulate up to 20 μg of exudate/mg root dry weight. The biosynthesis pathway involves unique fatty acid desaturases which produce an atypical 16:3 fatty acyl-CoA starter unit for an alkylresorcinol synthase that catalyzes the formation of a pentadecatrienylresorcinol intermediate. This intermediate is then methylated by SAM-dependent O-methyltransferases and dihydroxylated by cytochrome P450 monooxygenases. An EST data set derived from a S. bicolor root hair-specific cDNA library contained all the candidate sequences potentially encoding enzymes involved in the sorgoleone biosynthetic pathway. Sorgoleone interferes with several molecular target sites, including inhibition of photosynthesis in germinating seedlings. Sorgoleone is not translocated acropetally in older plants, but can be absorbed through the hypocotyl and cotyledonary tissues. Therefore, the mode of action of sorgoleone may be the result of inhibition of photosynthesis in young seedlings in concert with inhibition of its other molecular target sites in older plants. Due to its hydrophobic nature, sorgoleone is strongly sorbed in soil which increases its persistence, but experiments show that it is mineralized by microorganisms over time. 相似文献
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Two kinds of carboxypeptidases (F–I, F–II) were purified from the sarcocarp of watermelon (Citrullus vulgaris, var. Shimao). F–I was not purified to homogeneity. F–II was homogeneous on ultracentrifugal analysis, but a trace of impurity was detected at high concentrations by disc electrophoresis.F–I was optimally active and stable at pH 5.0~5.5 and was strongly inhibited by DFP and HgCl2, but not by EDTA. The molecular weight and isoelectric point were 89,000 and 4.4, respectively.F–II was optimally active at pH 5.0 ~ 5.5 and was most stable at pH 5.5 ~ 7.0. It was completely inhibited by DFP and HgCl2, but not by EDTA and 1, 10-phenanthroline, and it hydrolyzed an oligopeptide containing proline, glutamic acid, lysine and several neutral amino acids, sequentially from the C-terminal. The molecular weight and isolelectric point were 110,000 (5.1 S) and 5.0, respectively.The similarity of enzymatic properties of both the present enzymes to those of other plant carboxypeptidases and pig kidney cathepsin A are discussed. 相似文献
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Dong W. Choi Young S. Do Corbin J. Zea Marcus T. McEllistrem Sung-W. Lee Jeremy D. Semrau Nicola L. Pohl Clint J. Kisting Lori L. Scardino Scott C. Hartsel Eric S. Boyd Gill G. Geesey Theran P. Riedel Peter H. Shafe Kim A. Kranski John R. Tritsch William E. Antholine Alan A. DiSpirito 《Journal of inorganic biochemistry》2006,100(12):2150
Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ. 相似文献
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