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排序方式: 共有963条查询结果,搜索用时 15 毫秒
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Dagmar Jičínská Eduard Brabec Marcel Rejmánek Jan Jeník Joří Haager Josef Holub Věroslav Samek Hana Rambousková Josef Holub Marie Naděžda Končalová Robert Neuhäusl Josev Kyncl František Krahuleo Jaroslav Dobrý Blanka Úlehlová Jiří Úlehla Eliška Rybníčková Kamil Rybníček 《Folia Geobotanica》1982,17(4):431-448
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Mao S Bouygues M Welch C Biba M Chilenski J Schinazi RF Liotta DC 《Bioorganic & medicinal chemistry letters》2004,14(19):4991-4994
The beta-D-enantiomer of FDOC (2',3'-dideoxy-5-fluoro-oxacytidine) exhibits potent anti-HIV-1 activity. It was obtained in optically pure form by employing a tandem kinetic resolution/chiral salt crystallization protocol. In addition, conditions were developed that allowed the unwanted butyrate ester of the L-enantiomer of FDOC to be racemized. This material could then be recycled in future resolutions. 相似文献
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Identification and structure of a putative Ca2+-binding domain at the C terminus of AQP1 总被引:2,自引:0,他引:2
Fotiadis D Suda K Tittmann P Jenö P Philippsen A Müller DJ Gross H Engel A 《Journal of molecular biology》2002,318(5):1381-1394
Aquaporin-1 (AQP1) is the first functionally identified aquaporin of a growing family of membrane water channels found in all forms of life. Recently, a possible secondary function as a cyclic guanosine monophosphate (cGMP) gated ion channel was attributed to AQP1. We have reconstituted purified protein from bovine and human red blood cell membranes into highly ordered 2D crystals. The topography of both AQP1s was determined by electron microscopy from freeze-dried, unidirectionally metal-shadowed 2D crystals as well as from surface topographs of native crystals recorded in buffer solution with the atomic force microscope (AFM). In spite of the high level of sequence homology between bovine and human AQP1, the surfaces showed distinct differences. Alignment of both sequences and comparison of the acquired surface topographies with the atomic model of human AQP1 revealed the topographic changes on the surface of bovine AQP1 to be induced by a few amino acid substitutions. A striking degree of sequence homology was found between the carboxyl-terminal domains of AQP1s from different organisms and EF-hands from Ca2+-binding proteins belonging to the calmodulin superfamily, suggesting the existence of a Ca2+-binding site at the C terminus of AQP1 instead of the putative cGMP-binding site reported previously. To unveil its position on the acquired surface topographies, 2D crystals of AQP1 were digested with carboxypeptidase Y, which cleaves off the intracellular C terminus. Difference maps of AFM topographs between the native and the peptidase-treated AQP1s showed the carboxylic tail to be close to the 4-fold symmetry axis of the tetramer. SDS-PAGE and matrix-assisted laser desorption/ionisation mass spectrometry of native and decarboxylated bovine and human AQP1 revealed that the EF-hand motif found at the C terminus of AQP1 was partially resistant to peptidase digestion. The importance of the C-terminal domain is implicated by structural instability of decarboxylated AQP1. A possible role of the C terminus and calcium in translocation of AQP1 in cholangiocytes from intracellular vesicles to the plasma membrane and in triggering its fusion is discussed. Functional studies are now required to identify the physiological role of the Ca2+-binding site. 相似文献
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Aruoma OI Moncaster JA Walsh DT Gentleman SM Ke B Liang YF Higa T Jen LS 《Free radical research》2003,37(1):91-97
Injection of the glutamate agonist N-methyl-D-aspartate (NMDA) into the vitreous body of rats resulted in severe degeneration of neurons in the retina, with a loss of 81% of ganglion cells and 43% of non-ganglion cells. The cocktail EM-X is a novel antioxidant drink derived from ferment of unpolished rice, papaya and sea-weeds with effective microorganisms (EM-X). In animals treated with an intraperitoneal injection of EM-X, the loss of ganglion cells was reduced to 55% and that of non-ganglion cells to 34% when compared to untreated NMDA-injected retinas. Cell degeneration resulting from NMDA excitotoxicity, is thought to be mediated via oxidative stress mechanisms. The neuroprotective effect of the EM-X in this system is therefore likely to be due, at least in part, to its flavonoids, saponins, vitamin E and ascorbic content. 相似文献
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Lijuan Sun Sanjay Verma Navin Michael Siew Pang Chan Jianhua Yan Suresh Anand Sadananthan Stefan G. Camps Hui Jen Goh Priya Govindharajulu John Totman David Townsend Julian Pak‐Nam Goh Lei Sun Bernhard Otto Boehm Su Chi Lim Siew Kwan Sze Christiani Jeyakumar Henry Houchun Harry Hu S. Sendhil Velan Melvin Khee‐Shing Leow 《Obesity (Silver Spring, Md.)》2019,27(9):1434-1442
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