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41.
The low-molecular-mass form of two distinct catechol O-methyltransferase activities (S-adenosyl-L-methionine: catechol O-methyltransferase, COMT, EC 2.1.1.6) has been purified to homogeneity from rat liver using 40-70% ammonium sulfate precipitation, gel filtration on Sephadex G-100, adsorption on hydroxyapatite C and ion-exchange chromatography on DEAE-Sepharose CL-6B. The relative molecular mass Mr, determined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis is 22 400 +/- 500. Irradiation of the enzyme in the presence of 8-azido-[methyl-3H]AdoMet results in the specific labeling of the catalytic site of the enzyme. Photolabeling was successful with crude COMT preparations and with the isolated enzyme. Immunocytochemical studies present new information about the localization of the low-molecular-mass form in the liver parenchyma. Subcellularly COMT immunoreactivity could be attributed exclusively to the compartment with glycogen granules. Nucleus, mitochondria and endoplasmic reticulum showed no immunostaining. 相似文献
42.
Ulrike Rosenfellner Franz Zehetner Martin H. Gerzabek 《Soil & Sediment Contamination》2009,18(6):685-687
Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road. 相似文献
43.
44.
Mutagenic activity of nine N,N-disubstituted hydrazines in the Salmonella/mammalian microsome assay.
P A Nielsen A Lagersted S Danielsen A A Jensen J Hart J C Larsen 《Mutation research》1992,278(4):215-226
The mutagenic activity of N,N-dimethyl-, N,N-diethyl-, N,N-dibutyl-, N,N-diisobutyl-, N,N-di(p-tolyl)-, N-ethyl-N-phenyl-, N,N-dibenzyl-, N,N-diphenyl- and N,N-diisopropylhydrazine was examined in the Salmonella/mammalian microsome assay using the strains TA1535, TA1537, TA97, TA98, TA100, TA102 and TA1530. All nine hydrazines were mutagenic in at least one tester strain, although of borderline significance for some of the compounds. The mutagenic potencies of the hydrazines varied 2-3 orders of magnitude, from very weak to moderate mutagenic activity. In general, the addition of S9 resulted in a lowering of the mutagenic activity and a lowering of the toxic properties of the hydrazines. The test results were relatively difficult to evaluate due to toxic effects of many of the test compounds on the test bacteria which may have resulted in an underestimation of the mutagenic potencies of some of the compounds. The pattern of mutagenic activity of the hydrazines in the different tester strains indicates that more than one mechanism of action may be involved in the mutagenicity. 相似文献
45.
46.
Michael Gewecke Martin Woike 《Ethology : formerly Zeitschrift fur Tierpsychologie》1978,47(3):293-298
Analysis of the flight behaviour of siskins (Carduelis spinus) was made possible by tethering them with a harness to a flight balance in a wind tunnel. It could be shown that the breast feathers work as an air-current sense organ influencing the siskins' flight pattern and the aerodynamic parameters. 相似文献
47.
48.
Rachel M. Haywood Andrew W. D. Claxson Geoffrey E. Hawkes David P. Richardson Declan P. Naughton Gregory Coumbarides Jane Hawkes Edward J. Lynch Martin C. Grootveld 《Free radical research》1995,22(5):441-482
High field (400 and 600 MHz) proton NMR spectroscopy has been employed to investigate the thermally-induced autoxidation of glycerol-bound polyunsaturated fatty acids present in intact culinary frying oils and fats. Heating of these materials at 180°C for periods of 30, 60 and 90 min. generated a variety of peroxidation products, notably aldehydes (alkanals, trans-2-alkenals and alka-2, 4-dienals) and their conjugated hydroperoxydiene precursors. Since such aldehydes appear to be absorbed into the systemic circulation from the gut in vivo, the toxicological significance of their production during standard frying practices is discussed. 相似文献
49.
50.
P. E. Hessler P. E. Larsen A. I. Constantinou K. H. Schram J. M. Weber 《Applied microbiology and biotechnology》1997,47(4):398-404
A search for an abundant and economical source of isoflavones, particularly genistein, led to the discovery that the erythromycin-producing
organism Saccharopolyspora erythraea also produces this promising new cancer-prevention agent. Erythromycin fermentation is a large-scale, soybean-based process
used world-wide for the commercial production of this medically important antibiotic. Results from this study indicate that
genistin (the glucoside form of genistein), which is added to the fermentation in the soybean media, was converted to genistein
through the action of a β-glucosidase produced by the organism. Genistein was co-extracted with erythromycin from the fermentation
broth, then separated from erythromycin during the second step of the purification process for the production of erythromycin.
Received 10 September 1996 / Received revision: 22 November 1996 / Accepted: 7 December 1996 相似文献