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Characterization of a Human Serum Inhibitor of Clostridium histolyticum Proteinase(s) 总被引:2,自引:1,他引:1
Normal animal sera inhibit at least one Clostridium histolyticum proteinase. An assay procedure based on immune hemolysis was developed for the estimation of this inhibition. This inhibitory activity occurs in various levels in the sera of different animal species. The highest titers have been obtained with rat sera. The inhibitory activity from human serum was isolated and purified 16- to 27-fold by Sephadex G-200 gel filtration and diethylaminoethyl cellulose or hydroxylapatite chromatography. The properties of the human serum inhibitor of the clostridial proteinase were compared with a trypsin inhibiting factor found in the partially purified preparations. Identical behavior of the two inhibitory factors was observed when measured by heat inactivation, beta-mercaptoethanol sensitivity, pH stability, and sucrose gradient centrifugation. The inhibitory factor has an approximate sedimentation coefficient (S(20,w)) of 17. Goat anti-alpha-2-macroglobulin specifically precipitated the clostridial proteinase inhibitor from a partially purified preparation. 相似文献
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Control by ethylene of arginine decarboxylase activity in pea seedlings and its implication for hormonal regulation of plant growth 总被引:4,自引:3,他引:1
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Activity of arginine decarboxylase in etiolated pea seedlings appears 24 hours after seed imbibition, reaches its highest level on the 4th day, and levels off until the 7th day. This activity was found in the apical and subapical tissue of the roots and shoots where intensive DNA synthesis occurs. Exposure of the seedlings to ethylene greatly reduced the specific activity of this enzyme. The inhibition was observed within 30 min of the hormone application, and maximal effect—90% inhibition—after 18 hours. Ethylene at physiological concentrations affected the enzyme activity; 50% inhibitory rate was recorded at 0.12 microliters per liter ethylene and maximal response at 1.2 microliters per liter. Ethylene provoked a 5-fold increase in the Kmapp of arginine decarboxylase for its substrate and reduced the Vmaxapp by 10-fold. However, the enzyme recovered from the inhibition and regained control activity 7 hours after transferral of the seedlings to ethylene-free atmosphere. Reducing the endogenous level of ethylene in the tissue by hypobaric pressure, or by exposure to light, as well as interfering with ethylene action by treatment with silver thiosulfate or 2,5-norbornadiene, caused a gradual increase in the specific activity of arginine decarboxylase in the apical tissue of the etiolated seedlings. On the basis of these findings, the possible control of arginine decarboxylase activity by endogenous ethylene, and its implication for the hormone effect on plant growth, are discussed. 相似文献
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Topp S Reynoso CM Seeliger JC Goldlust IS Desai SK Murat D Shen A Puri AW Komeili A Bertozzi CR Scott JR Gallivan JP 《Applied and environmental microbiology》2010,76(23):7881-7884
We developed a series of ligand-inducible riboswitches that control gene expression in diverse species of Gram-negative and Gram-positive bacteria, including human pathogens that have few or no previously reported inducible expression systems. We anticipate that these riboswitches will be useful tools for genetic studies in a wide range of bacteria. 相似文献
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Background
The statistical modeling of biomedical corpora could yield integrated, coarse-to-fine views of biological phenomena that complement discoveries made from analysis of molecular sequence and profiling data. Here, the potential of such modeling is demonstrated by examining the 5,225 free-text items in the Caenorhabditis Genetic Center (CGC) Bibliography using techniques from statistical information retrieval. Items in the CGC biomedical text corpus were modeled using the Latent Dirichlet Allocation (LDA) model. LDA is a hierarchical Bayesian model which represents a document as a random mixture over latent topics; each topic is characterized by a distribution over words. 相似文献6.
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Estimating the rate of evolution of the rate of molecular evolution 总被引:35,自引:13,他引:22
A simple model for the evolution of the rate of molecular evolution is
presented. With a Bayesian approach, this model can serve as the basis for
estimating dates of important evolutionary events even in the absence of
the assumption of constant rates among evolutionary lineages. The method
can be used in conjunction with any of the widely used models for
nucleotide substitution or amino acid replacement. It is illustrated by
analyzing a data set of rbcL protein sequences.
相似文献
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A proteinase fraction inhibiting the hemolytic activity of guinea pig complement was obtained from supernatant fluids of Clostridium histolyticum cultures and purified 150- to 350-fold by ammonium sulfate precipitation, Sephadex G-75 gel filtration, and diethylaminoethyl cellulose chromatography. An assay was developed based on the inactivation of hemolytic complement. Partially purified anticomplementary preparations were active against casein and were capable of "solubilizing" Escherichia coli endotoxin. Two components were found by differential heat inactivation, with complement and casein as substrates, but only one of these components was active against endotoxin. The more heat-stable activity, showing 50% inactivation at about 47 C, was characterized as to pH and ionic strength optima and sensitivity to reagents such as cysteine, beta-mercaptoethanol, ethylenediaminetetraacetate, and heavy metals. 相似文献
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Vipond C Mulloy B Rigsby P Burkin K Bolgiano B;the MenC IS Working Group 《Biologicals》2012,40(5):353-363
Meningococcal group C (MenC) plain polysaccharide (PS) and conjugate vaccines are primarily evaluated by physicochemical methods to ensure that batches are consistently manufactured. As different assays are employed to quantify the MenC PS content of final formulations and bulk intermediaries, there is a need for an International MenC PS Standard to calibrate internal references used in the different laboratories. Twelve laboratories from nine different countries participated in a collaborative study to determine the MenC PS content of a candidate International Standard MenC PS preparation (08/214) and to assess its suitability. On the basis of the results from this study the candidate standard 08/214 was established as an International Standard for the quantification of MenC PS content in vaccines and components. It has a content of 1.192 ± 0.192 mg MenC PS/ampoule (expanded uncertainty with coverage factor of k = 2.365 corresponding to a 95% level of confidence), as determined by the resorcinol assays carried out by eight of the participating laboratories. The standard is available from The National Institute of Biological Standards and Control who act as guardians and distributors of the material under the auspices of WHO. 相似文献
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