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1.
The accumulation of polyphosphate in Acinetobacter spp. 总被引:5,自引:0,他引:5
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Dr. Jan A. M. de Bont Annie Scholten Will J. J. van den Tweel 《Current microbiology》1985,12(5):267-271
The microbial potential to degrade acetylenic compounds (alkynes) was investigated, and several fungi and bacteria were isolated on 2-propyn-1-ol, 3-butyn-1-ol, propynoic acid, and 2-butyne-1,4-diol. The results indicate that a wide variety of microorganisms may degrade alkynes in nature. 相似文献
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P C Babbitt G L Kenyon B M Martin H Charest M Slyvestre J D Scholten K H Chang P H Liang D Dunaway-Mariano 《Biochemistry》1992,31(24):5594-5604
We have deduced the nucleotide sequence of the genes encoding the three components of 4-chlorobenzoate (4-CBA) dehalogenase from Pseudomonas sp. CBS-3 and examined the origin of these proteins by homology analysis. Open reading frame 1 (ORF1) encodes a 30-kDa 4-CBA-coenzyme A dehalogenase related to enoyl-coenzyme A hydratases functioning in fatty acid beta-oxidation. ORF2 encodes a 57-kDa protein which activates 4-CBA by acyl adenylation/thioesterification. This 4-CBA:coenzyme A ligase shares significant sequence similarity with a large group of proteins, many of which catalyze similar chemistry in beta-oxidation pathways or in siderophore and antibiotic synthetic pathways. These proteins have in common a short stretch of sequence, (T,S)(S,G)G(T,S)(T,E)G(L,X)PK(G,-), which is particularly highly conserved and which may represent an important new class of "signature" sequence. We were unable to find any proteins homologous in sequence to the 16-kDa 4-hydroxybenzoate-coenzyme A thioesterase encoded by ORF3. Analysis of the chemistry and function of the proteins found to be structurally related to the 4-CBA:coenzyme A ligase and the 4-CBA-coenzyme A dehalogenase supports the proposal that they evolved from a beta-oxidation pathway. 相似文献
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A freshwater sediment from a ditch of a peat grassland near Zegveld (Province of Utrecht, The Netherlands) was investigated for its potential methanogenic and syntrophic activity and the influence of sulfate and nitrate on these potential activities. Methanogenesis started after a 10 days lagphase. After 35–40 days aceticlastic methanogens were sufficiently enriched to cause a net decrease of acetate. In the presence of sulfate methane formation was only slightly affected. The addition of nitrate led to an outcompetion of aceticlastic methanogens by nitrate reducers. When inorganic electron acceptors were absent, substrates like propionate and butyrate were converted by syntrophic methanogenic consortia. Addition of inorganic electron acceptors resulted in an outcompetition of the syntrophic propionate and butyrate degrading consortia by the sulfate and nitrate reducers. 相似文献
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Purification and characterization of the Tetrahymena pyriformis P-C bond forming enzyme phosphoenolpyruvate phosphomutase 总被引:1,自引:0,他引:1
In this paper the purification and characterization of the Tetrahymena pyriformis enzyme phosphoenolpyruvate phosphomutase are described. PEP phosphomutase was first fractionated from T. pyriformis cellular extract by using 70% ammonium sulfate. Chromatography of the crude protein fraction on a DEAE-cellulose column followed by phenyl-Sepharose column chromatography and then Bio-Gel P-200 column chromatography afforded pure PEP phosphomutase in an approximate overall yield of 70 units/150 g of cells. The maximum turnover number observed for PEP phosphomutase catalysis of the phosphonopyruvate----PEP reaction is 38 s-1 (25 degrees C). The enzyme was shown to be a homodimer of 38,000-dalton subunits and to require a divalent metal ion for activity. Mg2+ (relative Vm = 1), Co2+ (rel Vm = 0.5), Zn2+ (rel Vm = 0.4), and Mn2+ (rel Vm = 0.3) each satisfied the cofactor requirement. Binding of the physiological cofactor, Mg2+ (Ki = 0.3 mM at pH 7.5), and phosphonopyruvate (Km = 2 microM at pH 7.5) was found to be ordered, with cofactor binding preceding substrate binding. Within the pH range of 5-9 catalysis (Vm) was found to be pH independent, while phosphonopyruvate binding dropped at acidic and basic pH. 相似文献
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The staining of male Chinese hamster chromosomes at meiotic prophase with several banding techniques is described. C-banding results only occasionally in well-differentiated pachytene and diakinesis bivalents. Meiotic C-bands are small compared with those in somatic metaphase chromosomes. In mice C-bands mainly consist of highly repetitive satellite DNA, whereas in Chinese hamsters the majority of the DNA in C-bands is not or hardly repetitive. Especially in Chinese hamsters both the degree of chromatin despiralisation and the folding pattern of the chromatin drastically reduce the distinction of C-bands in late meiotic prophasc chromosomes. In contrast to the situation in mice, C-heterochromatin associations are never observed in Chinese hamster spermatocytes. It is assumed that the presence of satellite DNA rather than constitutive heterochromatin is the basis for the associations of the paracentromeric chromosome regions in mice. The location and behaviour of AT- and GC-rich DNA in Chinese hamster primary spermatocytes is studied with base-specific fluorochromes (H 33258 and Chromomycin A3 for AT-and GC-rich DNA respectively), in combination with a pretreatment with base-specific non-fluorescent antibiotics (Actinomycin D and Netropsin for GC-and AT-rich DNA respectively). No indications are found for the clustering of AT-or GC-rich DNA in Chinese hamster pachytene nuclei. A comparison of banding patterns observed in somatic metaphases and in diakinesis gives some information about the partial homology of the X and Y chromosome. The results are conflicting. The short arm of the Y chromosome is homologous with a part of the X chromosome. According to the C-band pattern the long arm of the X chromosome is involved in the pairing with Y, whereas fluorescence banding patterns indicate that it is the short arm of X. 相似文献
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Quantitative succinate-dehydrogenase histochemistry. I. A Methodological study on mammalian and fish muscle. 总被引:1,自引:0,他引:1
In enzyme histochemistry formazan production can be used as a measure for oxidative enzyme activity. The formazan deposits can be measured quantitatively per cell with a scanning and integrating microspectrophotometer. Optimal conditions are described for the estimation of histochemical succinate dehydrogenase activity in sections of fish bodymusculature and mouse soleus and plantaris muscle. It is shown that when proper measuring conditions are chosen a ditetrazolium salt (TNBT) can be used in quantitative enzyme histochemistry and that the optimal conditions for the histochemical succinate dehydrogenase reaction in muscle fibres of fish and mouse muscle are somewhat different for these two species. The differences in pH, temperature and succinate sensitivity are the most prominent. 相似文献
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