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121.
Eddy van der Linden Bart W Faber Boris Bleijlevens Tanja Burgdorf Michael Bernhard B?rbel Friedrich Simon P J Albracht 《European journal of biochemistry》2004,271(4):801-808
The soluble, cytoplasmic NAD+-reducing [NiFe]-hydrogenase from Ralstonia eutropha is a heterotetrameric enzyme (HoxFUYH) and contains two FMN groups. The purified oxidized enzyme is inactive in the H2-NAD+ reaction, but can be activated by catalytic amounts of NADH. It was discovered that one of the FMN groups (FMN-a) is selectively released upon prolonged reduction of the enzyme with NADH. During this process, the enzyme maintained its tetrameric form, with one FMN group (FMN-b) firmly bound, but it lost its physiological activity--the reduction of NAD+ by H2. This activity could be reconstituted by the addition of excess FMN to the reduced enzyme. The rate of reduction of benzyl viologen by H2 was not dependent on the presence of FMN-a. Enzyme devoid of FMN-a could not be activated by NADH. As NADH-dehydrogenase activity was not dependent on the presence of FMN-a, and because FMN-b did not dissociate from the reduced enzyme, we conclude that FMN-b is functional in the NADH-dehydrogenase activity catalyzed by the HoxFU dimer. The possible function of FMN-a as a hydride acceptor in the hydrogenase reaction catalyzed by the HoxHY dimer is discussed. 相似文献
122.
123.
Background
Routine antibiotic prophylaxis following snakebite is not recommended but evidence suggests that it may be common practice in Zimbabwe. This study set out to determine and describe the extent of this practice at Parirenyatwa Hospital, a large teaching hospital in Zimbabwe 相似文献124.
Sean R Eddy 《BMC bioinformatics》2002,3(1):18-16
Background
Covariance models (CMs) are probabilistic models of RNA secondary structure, analogous to profile hidden Markov models of linear sequence. The dynamic programming algorithm for aligning a CM to an RNA sequence of length N is O(N 3) in memory. This is only practical for small RNAs. 相似文献125.
Eddy Risseeuw Marry E.I. Franke-van Dijk Paul J.J. Hooykaas 《The Plant journal : for cell and molecular biology》1997,11(4):717-728
To develop a model system for studies of homologous recombination in plants, transgenic Nicotiana tabacum and Nicotiana plumbaginifolia lines were generated harbouring a single target T-DNA containing the negative selective codA gene encoding cytosine deaminase (CD) and the β-glucuronidase (GUS) gene. Subsequently, the target lines were transformed with a replacement-type T-DNA vector in which the CD gene and the GUS promoter had been replaced with a kanamycin-resistance gene. For both Nicotiana species kanamycin-resistant lines were selected which had lost the CD gene and the GUS activity. One tobacco line was the result of a precise gene targeting event. However, most other lines were selected due to a chromosomal deletion of the target locus. The deletion frequency of the target locus varied between target lines, and could be present in up to 20% of the calli which were grown from leaf protoplasts. T-DNA transfer was not required for induction of the deletions, indicating that the target loci were unstable. A few lines were obtained in which the target locus had been deleted partially. Sequence analysis of the junctions revealed deletion of DNA sequences between microhomologies. We conclude that T-DNAs, which are stable during plant development as well as in transmission to the offspring, may become unstable during propagation in callus tissue. The relationships between callus culture, genetic instability and the process of T-DNA integration and deletion in the plant genome are discussed. 相似文献
126.
Development of an arabinose-fermenting Zymomonas mobilis strain by metabolic pathway engineering. 总被引:4,自引:0,他引:4
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The substrate fermentation range of the ethanologenic bacterium Zymomonas mobilis was expanded to include the pentose sugar, L-arabinose, which is commonly found in agricultural residues and other lignocellulosic biomass. Five genes, encoding L-arabinose isomerase (araA), L-ribulokinase (araB), L-ribulose-5-phosphate-4-epimerase (araD), transaldolase (talB), and transketolase (tktA), were isolated from Escherichia coli and introduced into Z. mobilis under the control of constitutive promoters that permitted their expression even in the presence of glucose. The engineered strain grew on and produced ethanol from L-arabinose as a sole C source at 98% of the maximum theoretical ethanol yield, based on the amount of consumed sugar. This indicates that arabinose was metabolized almost exclusively to ethanol as the sole fermentation product, with little by-product formation. Although no diauxic growth pattern was evident, the microorganism preferentially utilized glucose before arabinose, apparently reflecting the specificity of the indigenous facilitated diffusion transport system. This microorganism may be useful, along with the previously developed xylose-fermenting Z. mobilis (M. Zhang, C. Eddy, K. Deanda, M. Finkelstein, and S. Picataggio, Science 267:240-243, 1995), in a mixed culture for efficient fermentation of the predominant hexose and pentose sugars in agricultural residues and other lignocellulosic feedstocks to ethanol. 相似文献
127.
Y S Fan R L Eddy M G Byers L L Haley W M Henry N J Nowak T B Shows 《Cytogenetics and cell genetics》1989,52(1-2):83-84
The gene for the human mineralocorticoid receptor (MLR) was previously localized to chromosome 4. Here, we have localized this gene to 4q31.2 by in situ hybridization. This precise mapping of MLR will assist in the linkage analysis and genetic characterization of pseudohypoaldosteronism, an autosomal recessive disorder which likely results from a defect in the MLR gene. 相似文献
128.
129.
Sequential biochemical and morphological events during assembly of the fertilization membrane of the sea urchin. 总被引:1,自引:0,他引:1
The fertilization membrane of Strongylocentrotus purpuratus undergoes changes in morphology, solubility, and permeability during the process of hardening. As the fertilization membrane elevates from the egg surface, it retains casts of the tips of the microvillous processes of the plasma membrane. The dome-shaped microvillar casts become angular at the same time that the fertilization membrane becomes resistant to solubilization in mercaptan solutions. 2-4 min after this morphological and chemical transition, the fertilization membrane becomes impermeable to the lectin conconavalin A, as monitored by binding of 125I- or fluorescein-labeled concanavalin A. Glycine ethyl ester inhibits the changes in morphology, solubility, and permeability, whereas sodium sulfite inhibits only the permeability block and resistance to solubilization by mercaptans. Parthenogenetic activation with the divalent ionophore, A23187, elicits fertilization membrane elevation more rapidly than does activation by fertilization; however, the morphological and permeability changes characteristic of hardening proceed more slowly. Elevation and hardening of the fertilization membrane thus appear to be discrete, multiple-step assembly processes that occur in fixed sequence, with kinetics that are affected by the mechanism of cortical granule exocytosis. 相似文献
130.
P. A. Rodriguez R. Takigiku L. D. Lehman-McKeeman M. L. Fey C. L. Eddy D. Caudill 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,563(2)
A Perkin Elmer 3920 gas chromatograph, equipped with a versatile inlet system (i.e. an injector/trap), was interfaced to a radioactivity detector and a mass-selective detector (H/P 5970B) to identify 14C-labeled compounds. The use of a pre-trap as a demountable, programmable-temperature injector, in conjunction with the injector/trap, allowed the introduction of 0.5-ml samples of rat kidney cytosol extracts to 0.32 mm I.D. capillary columns. The instrumentation greatly facilitated the identification of the major radiolabeled metabolite of d-limonene associated with the male rat-specific protein α2u-globulin as 1,2-cis-d-limonene oxide. 相似文献