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491.
Per E. M. Siegbahn Margareta R.A. Blomberg Maria Wirstam née Pavlov Robert H. Crabtree 《Journal of biological inorganic chemistry》2001,6(4):460-466
The catalytic cycle for the heterolytic splitting of H2 by Ni-Fe hydrogenase has been investigated in four recent quantum chemical studies. The mechanisms proposed are described and compared. Although there are clear differences in these mechanisms and in the assignments of the different states observed experimentally, there are also important points of concensus. 相似文献
492.
493.
Per-Olof Eriksson Anders Eriksson Margareta Ringqvist Lars-Eric Thornell 《Histochemistry and cell biology》1980,65(3):193-205
Summary The reliability of muscle fibre typing of post mortem specimens was investigated with special reference to the influence of time and temperature. In specimens stored at +4° C, muscle fibre typing could be reliably performed up to at least ten and fifteen days post mortem for the masseter and biceps brachii muscles respectively. The corresponding figures for storage at room temperature were three and six days. The difference in the preservation of enzyme activity between masticatory and limb muscles might be related to the demonstrated difference in the fibre type composition and thus the enzyme content and energy sources. 相似文献
494.
Peter Moldéus Peter J. OBrien Hj?rdis Thor Margareta Berggren Sten Orrenius 《FEBS letters》1983,154(2):411-415
Horseradish peroxidase-catalyzed N-demethylation of aminopyrine and dimethylaniline results in generation of free radical intermediates which can interact with glutathione (GSH) to form a glutathione radical. This can either dimerize to yield glutathione disulfide or react with O2 to form oxygenated products of glutathione. Ethylmorphine is not a substrate in the peroxidase-mediated reaction, and free radical intermediates which react with GSH, are not formed from aminopyrine and dimethylaniline when the horseradish peroxidase/H2O2 system is replaced by liver microsomes and NADPH. Therefore, it appears unlikely that formation of free radical intermediates can be responsible for the depletion of GSH observed during N-demethylation of several drugs in isolated liver cells. 相似文献
495.
A new flavone 5,6-dimethoxy-3,7,4′-trihydroxyflavone was isolated from the external leaf resin of Adenostoma sparsifolium and identified by spect 相似文献
496.
Sara Aspengren Heln Nilsson Skld Gabriela Quiroga Lena Mrtensson Margareta Wallin 《Pigment cell & melanoma research》2003,16(1):59-64
The effects of melatonin and noradrenaline (NA) on bi‐directional melanosome transport were analysed in primary cultures of melanophores from the Atlantic cod. Both agents mediated rapid melanosome aggregation, and by using receptor antagonists, melatonin was found to bind to a melatonin receptor whereas NA binds to an α2‐adrenoceptor. It has previously been stated that melatonin‐mediated melanosome aggregation in Xenopus is coupled with tyrosine phosphorylation of a so far unidentified high molecular weight protein and we show that although acting through different receptors and through somewhat different downstream signalling events, tyrosine phosphorylation is of the utmost importance for melanosome aggregation mediated by both NA and melatonin in cod melanophores. Together with cyclic adenosine 3‐phosphate‐fluctuations, tyrosine phosphorylation functions as a switch signal for melanosome aggregation and dispersion in these cells. 相似文献