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1.
Makoto Misono 《Molecular Engineering》1993,3(1-3):193-203
First, fundamental properties (structure, acid and redox properties) and advantages of solid polyoxometalate catalysts (catalyst design by acid and redox control, molecularity, unusual reaction field and unique basicity) are explained. Then, the mechanism of alcohol dehydration elucidated by direct observation of reaction intermediates by solid-state NMR and the very high activity of Cs2.5H0.5PW12O40 are described. Finally several industrial applications of polyoxometalate catalysts are briefly introduced placing stress on the role of unique chemical properties of polyoxometalates. 相似文献
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K N Pandey T Inagami P R Girard J F Kuo K S Misono 《Biochemical and biophysical research communications》1987,148(2):589-595
The effects of synthetic atrial natriuretic factor (ANF) on the state of protein phosphorylation in plasma membranes of bovine adrenal cortex have been studied in vitro. ANF (1x10(-8)M - 1x10(-7)M) specifically inhibited the phosphorylation of two distinct proteins of 78 kDa and 240 kDa. Immunoblotting with specific antiserum to protein kinase C produced evidence that 78 kDa protein is most likely the protein kinase C whose phosphorylation is inhibited by both ANF and cGMP. However, cGMP did not affect the phosphorylation of 240 kDa protein, indicating a new cGMP-independent mechanism of ANF action in the adrenal, which is compatible with the lack of action of cGMP and its analogs in ANF-induced inhibition of aldosterone secretion from adrenal cortex. The inhibition of phosphorylation of putative protein kinase C by ANF or cGMP indicates a hitherto unknown signal transduction mechanism of ANF. 相似文献
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K.S. Misono R.T. Grammer H. Fukumi T. Inagami 《Biochemical and biophysical research communications》1984,123(2):444-451
Four peptides possessing both natriuretic activity and smooth muscle relaxant activity were isolated from rat atrium and their amino acid sequences determined. The four peptides designated ANF-I, ANF-II, ANF-III and ANF-IV containing 35, 31, 30 and 25 amino acid residues, respectively, were obtained in a molar ratio of 4:60:20:16. The predominant species ANF-II, which may represent the native form of ANF, has the following sequence: (H2N)-G-P-R-S-L-R-R-S-S-C-F-G-G-R-I-D-R-I-G-A-Q-S-G-L-G-C-N-S-F-R-Y-(COOH) in which Cys-10 and Cys-26 are disulfide linked. Cleavage of the aspartyl linkage at position 16 by staphylococcal protease caused complete inactivation, indicating that the ring conformation is essential. The dose-response relationships determined for the four pepdides in relaxing norepinephrine-induced contraction of rabbit thoracic aorta showed half-maximum relaxation at concentrations ranging from 1.5 × 10?9 to 2.5 × 10?9 M. Comparable dose-response relationships were observed in relaxation of carbacol-induced contraction of chick rectum strips as tested with ANF-II and ANF-IV. 相似文献
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Summary Correlated physiological and electron-microscopic studies were made on the source of calcium activating the contractile system (activator calcium) in dog coronary artery smooth muscle fibers. The magnitude of contracture tension induced by 100 mM K+ was dependent on external Ca2+ concentration and reduced or eliminated by factors known to reduce the Ca2+ spike or ca2+ influx. Little or no mechanical response was elicited by treatments known to cause release of intracellularly stored calcium. These results indicated that the contractile system is mainly activated by the inward movement of extracellular calcium. In accordance with the physiological experiments, electron-opaque pyroantimonate precipitate containing calcium was found in the lumina of caveolae, but not in any intracellular structures close to the plasma membrane, when the relaxed fibers were fixed in a 1% osmium tetroxide solution containing 2% potassium pyroantimonate. If the contracted fibers were fixed in the same solution, the pyroantimonate precipitate was diffusely distributed in the myoplasm in the form of numerous particles, while the precipitate in the caveolar lumina was scarcely seen. These findings are discussed in connection with the regulation of intracellular Ca2+ concentration in dog coronary artery smooth muscle. 相似文献
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Noboru Ōtake Haruo Seto Mitsuo Koenuma 《Bioscience, biotechnology, and biochemistry》2013,77(10):1879-1886
The complete 18C-NMR assignment of lysocellin sodium salt has been obtained based on the 13C-13C double labeling method and comparison with its retroaldol degradation product as well as a structurally related polyether antibiotic, lasalocid A.In parallel, the biosynthesis of lysocellin was investigated by feeding 13C-labeled precursors followed by analyzing the resulting labeling patterns of the 13C-NMR spectra; a pathway to the antibiotic molecule is suggested which proceeds through condensation of two butyrate, eight propionate and one acetate units.In addition, a conversion of butyrate to propionate during the metabolic process has been disclosed. 相似文献
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