排序方式: 共有18条查询结果,搜索用时 93 毫秒
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Haralampus-Grynaviski N Ransom C Ye T Rôzanowska M Wrona M Sarna T Simon JD 《Journal of the American Chemical Society》2002,124(13):3461-3468
Urocanic acid, UCA, is characterized by two electronic transitions in the UV-B (280-320 nm) which comprise its broad absorption spectrum and give rise to wavelength-dependent isomerization quantum yields. The absorption spectrum of UCA extends into the UV-A (320-400 nm). Given the UV-A component of sunlight is significantly greater than the UV-B component it is hypothesized even weak UV-A photochemistry of UCA could be important for in vivo responses to UV radiation. Degenerate pump-probe experiments performed on t-UCA at several wavelengths in the UV-A reveal an excited-state absorption that undergoes a rapid, approximately 1 ps decay. Photoacoustic experiments performed on both the cis and trans isomers reveal the formation of a long-lived intermediate following UV-A excitation. The efficiency and action spectra for this latter photoactive process are presented and are similar for both isomers of UCA. Cholesterol hydroperoxide assays designed to investigate the nature of the UV-A photoreactivity of t-UCA confirm the production of reactive oxygen species. The bimolecular rate constant for the quenching of singlet oxygen by t-UCA is determined to be 3.5 x 10(6) M(-1) s(-1). Taking into consideration recent theoretical calculations and jet expansion studies of the electronic structure of gas-phase t-UCA, a model is proposed to explain the isomerization and photoreactivity of t-UCA in solution over the UV-A region. 相似文献
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H. Kunz W. Dunstan F. Ransom und Otto Schweissinger 《Fresenius' Journal of Analytical Chemistry》1887,26(1):113-116
Ohne Zusammenfassung 相似文献
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Jiang B Xu D Allocco J Parish C Davison J Veillette K Sillaots S Hu W Rodriguez-Suarez R Trosok S Zhang L Li Y Rahkhoodaee F Ransom T Martel N Wang H Gauvin D Wiltsie J Wisniewski D Salowe S Kahn JN Hsu MJ Giacobbe R Abruzzo G Flattery A Gill C Youngman P Wilson K Bills G Platas G Pelaez F Diez MT Kauffman S Becker J Harris G Liberator P Roemer T 《Chemistry & biology》2008,15(4):363-374
Natural products provide an unparalleled source of chemical scaffolds with diverse biological activities and have profoundly impacted antimicrobial drug discovery. To further explore the full potential of their chemical diversity, we survey natural products for antifungal, target-specific inhibitors by using a chemical-genetic approach adapted to the human fungal pathogen Candida albicans and demonstrate that natural-product fermentation extracts can be mechanistically annotated according to heterozygote strain responses. Applying this approach, we report the discovery and characterization of a natural product, parnafungin, which we demonstrate, by both biochemical and genetic means, to inhibit poly(A) polymerase. Parnafungin displays potent and broad spectrum activity against diverse, clinically relevant fungal pathogens and reduces fungal burden in a murine model of disseminated candidiasis. Thus, mechanism-of-action determination of crude fermentation extracts by chemical-genetic profiling brings a powerful strategy to natural-product-based drug discovery. 相似文献
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P Ransom TA Arnold AL Thompson JC Buffet D O'Hare 《Dalton transactions (Cambridge, England : 2003)》2012,41(37):11267-11269
Synthesis, magnetic properties, NMR spectroscopy, and crystallographic details of an ethylene bridged hexamethylindenyl (EBI*) cerium iodide complex [(EBI*)CeI(THF)] are reported. 相似文献
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P. Jannasch R. Leiste W. D. Treadwell F. W. Foote R. S. Ransom F. Jean Roy F. Heath W. R. Schoeller A. R. Powell Th. D?ring Joseph Erlich Gastone Fiorentino A. H. Low G. v. Knorre L. Wolter L. L?wy F. P. Treadwell O. Brunner L. Losana E. Carozzi H. Brearley F. Ibbotson A. A. Blair C. M. Johnson und K. Seel 《Fresenius' Journal of Analytical Chemistry》1923,62(9):357-368
Ohne Zusammenfassung 相似文献
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Su DS Markowitz MK DiPardo RM Murphy KL Harrell CM O'Malley SS Ransom RW Chang RS Ha S Hess FJ Pettibone DJ Mason GS Boyce S Freidinger RM Bock MG 《Journal of the American Chemical Society》2003,125(25):7516-7517
Bradykinin (BK) plays an important role in the pathophysiological processes accompanying pain and inflammation. Selective bradykinin B1 receptor antagonists have been shown to be anti-nociceptive in animal models and could be novel therapeutic agents for the treatment of pain and inflammation. We have explored chemical modifications in a series of dihydroquinoxalinone sulfonamides to evaluate the effects of various structural changes on biological activity. The optimization of a screening lead compound, facilitated by a homology model of the BK B1 receptor, culminated in the discovery of a potent human BK B1 receptor antagonist. Results from site-directed mutagenesis studies and experiments in an animal pain model are presented. 相似文献
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Ransom C Balan V Biswas G Dale B Crockett E Sticklen M 《Applied biochemistry and biotechnology》2007,137(1-12):207-219
Commercial conversion of lignocellulosic biomass to fermentable sugars requires inexpensive bulk production of biologically active cellulase enzymes, which might be achieved through direct production of these enzymes within the biomass crops. Transgenic corn plants containing the catalytic domain of Acidothermus cellulolyticus E1 endo-1,4-beta glucanase and the bar bialaphos resistance coding sequences were generated after Biolistic (BioRad Hercules, CA) bombardment of immature embryo-derived cells. E1 sequences were regulated under the control of the cauliflower mosaic virus 35S promoter and tobacco mosaic virus translational enhancer, and E1 protein was targeted to the apoplast using the signal peptide of tobacco pathogenesis-related protein to achieve accumulation of this enzyme. The integration, expression, and segregation of E1 and bar transgenes were demonstrated, respectively, through Southern and Western blotting, and progeny analyses. Accumulation of up to 1.13% of transgenic plant total soluble proteins was detected as biologically active E1 by enzymatic activity assay. The corn-produced heterologous E1 could successfully convert ammonia fiber explosion-pretreated corn stover polysaccharides into glucose as a fermentable sugar for ethanol production, confirming that the E1 enzyme is produced in its active form. 相似文献