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Abstract Pseudomonas fluorescens EB carries genes for the catabolism of ethylbenzene and 1-phenylethanol on a plasmid. The size of the plasmid as measured by analysis of agarose electrophoresis gels after restriction endonuclease hydrolysis, was 253–267 kb. By treatment with Mitomycin C, mutants of EB strain were obtained bearing a plasmid which had undergone an extensive deletion of about 80 kb. These mutants have lost the ability to grow on ethylbenzene and 1-phenylethanol as well as to synthesize meta-cleavage enzymes. 相似文献
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A Banerjee M A Jordan R F Luduena 《Biochemical and biophysical research communications》1985,128(2):506-512
Incubation of phosphocellulose-purified tubulin with GSH at 30 degrees C results in an inhibition of colchicine binding activity. GSSG has a protective effect against the GSH-induced loss of colchicine-binding. Incubation of tubulin with GSH at 30 degrees C results in the formation of abnormal tubulin polymers which are insensitive to cold. Such aggregation is insensitive to antimicrotubular drugs. Aggregation is inhibited by GSSG but not by DTT or mercaptoethanol. GSH-induced aggregation is very sensitive to the ionic strength of the assembly medium; both the aggregation and colchicine binding inhibition induced by GSH are inhibited at higher ionic strength. These results indicate a very complex interaction of GSH with tubulin. 相似文献
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Ethanol Administration in the Rat Decreases Prostacyclin Production by Isolated Brain Microvessels 总被引:1,自引:0,他引:1
The effects of short- and long-term ethanol administration to rats on basal levels and formation of prostacyclin (PGI2) measured as 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), and on lipid class content and fatty acid composition of isolated brain microvessels (BMV) were studied. After acute treatment (2 h, at the peak of plasma ethanol concentration) basal 6-keto-PGF1 alpha levels in BMV and release on incubation were reduced to 50% of control values. After chronic administration (15 days), PGI2 release was reduced to about 40% of control values, without changes in basal levels. Total lipid, phospholipid, and cholesterol levels in BMV, measured after prolonged administration of alcohol, were not modified. Also, only minor changes in the fatty acid composition of individual phospholipid classes were detected. The observed reduction of PGI2 synthesis in BMV thus could not be related to changes of the fatty acid precursor pool in the preparation. Precursor release and/or the biosynthetic pathways may be affected by ethanol administration. 相似文献
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Arachidonic acid metabolism was evaluated in isolated rat hepatocytes after CCl4 exposure. CCl4 induced dose-dependently the synthesis and release of prostacyclin (PGI2) and thromboxane (TXB2). Treatment with prostaglandin E2 (PGE2) 30 min after exposure to CCl4, significantly reduced the cell damage as well as the release of TXB2 from the cells. 相似文献
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A sensitive and continuous fluorometric assay for phospholipase A2 using pyrene-labeled phospholipids in the presence of serum albumin 总被引:3,自引:0,他引:3
Phospholipase A2 activity can be determined fluorometrically in the presence of serum albumin using phospholipids labeled at the sn-2-acyl position with 10-pyrenyldecanoic acid. In the water reaction medium 10-pyrene phospholipids form vesicles and the monomer fluorescence of the pyrene is negligible due to pyrene-pyrene interaction. Upon phospholipid hydrolysis 10-pyrenyldecanoic acids are produced and tightly bind to albumin so that a monomer pyrene fluorescence is observed. We obtained an excellent parallelism between hydrolysis determined by a classical extraction method and that followed by direct and continuous spectrofluorometric recording of the monomer emission of pyrene. This assay can measure picomole amounts of phospholipids hydrolyzed per minute so that picogram quantities of phospholipases A2 from pancreas or from venoms can be measured. Phospholipase activity remains proportional to enzyme concentration over three orders of magnitude. The method can be used to quantify the phospholipase A2 activity of crude extracts of low specific activity. 相似文献
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