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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 340 (1991), S. 616-620 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In laboratory-scale experiments sea salt particles are exposed to SO2 at a temperature of 22°C and relative humidities of 40, 60 and 80%; the SO2 gas concentration is fixed to 0.2, 0.5 and 1.0 ppm (v), respectively. In further test series NO2 is added to the gas phase. As kinetic data the capacity values of the sea salt particles (mg formed sulfate/g dry aerosol) are determined as function of time and from this the reaction rates (mg formed sulfate/g dry aerosol and minute) are calculated in dependence of the yield. The relative humidity (r.h.) has proved to be a decisive reaction parameter. For example, the rate (at a reaction time of one hour) increases at a SO2 concentration of 0.5 ppm (v) from 0.01 to approx. 0.1 mg SO 4 2− /g·min, if the r.h. will increase from 40 to 80%. However, the gas concentration has only an importance at high humidities (where the reaction takes place in droplets) for the sulfate formation in sea salt aerosols. If the SO2 concentration is reduced from 1.0 to 0.2 ppm (v) at a r.h. of 80%, the rate will be decreased from 0.2 to about 0.07 mg SO 4 2− /g·min; however, at a r.h. of 60% from 0.075 to 0.04 mg SO 4 2− /g·min. As an increased sulfate formation but no nitrate formation can be detected when NO2 is added to the gas phase, it can be assumed that SO2 is oxidized in the electrolyte layer around the sea salt particles whereas NO2 is reduced. If NO2 (SO2:NO2=1:1) is added to the gas phase, the rate — for example at a r.h. of 40% — will be increased from 0.01 to 0.24 mg SO 4 2− /g·min.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0887-3585
    Keywords: antivirals ; Zovirax ; drug target ; drug binding ; enzyme structure ; intermolecular interactions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Antiherpes therapies are principally targeted at viral thymidine kinases and utilize nucleoside analogs, the triphosphates of which are inhibitors of viral DNA polymerase or result in toxic effects when incorporated into DNA. The most frequently used drug, aciclovir (Zovirax), is a relatively poor substrate for thymidine kinase and high-resolution structural information on drugs and other molecules binding to the target is therefore important for the design of novel and more potent chemotherapy, both in antiherpes treatment and in gene therapy systems where thymidine kinase is expressed. Here, we report for the first time the binary complexes of HSV-1 thymidine kinase (TK) with the drug molecules aciclovir and penciclovir, determined by X-ray crystallography at 2.37 Å resolution. Moreover, from new data at 2.14 Å resolution, the refined structure of the complex of TK with its substrate deoxythymidine (R = 0.209 for 96% of all data) now reveals much detail concerning substrate and solvent interactions with the enzyme. Structures of the complexes of TK with four halogen-containing substrate analogs have also been solved, to resolutions better than 2.4 Å. The various TK inhibitors broadly fall into three groups which together probe the space of the enzyme active site in a manner that no one molecule does alone, so giving a composite picture of active site interactions that can be exploited in the design of novel compounds. Proteins 32:350-361, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 340 (1991), S. 621-626 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The particle diameter has proved to be of decisive influence on the NO2 oxidation on particles of stack fly ash. The quantity of nitrate formed per gram stack fly ash increases with decreasing mean particle diameter of each grain fraction. The relative humidity gets only important at reaction times longer than 4 h where the NO2 conversions are higher at a relative humidity of 80% than at 90%. A similar behaviour of the nitrate formation is observed in reactions applying additionally a simulated solar radiation, but with slightly higher reaction capacities. However, a further reaction was suggested, superimposing the NO2 oxidation at reaction times longer than 6 h. Apart from the role in gas phase chemistry of NO2 the solar radiation does not affect the nitrate formation in or at the droplets. At present, examinations are carried out with a relative humidity of 40% supporting these assumptions.
    Type of Medium: Electronic Resource
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