共查询到20条相似文献,搜索用时 46 毫秒
1.
Summary A convenient synthesis of 5-deoxypyridoxal derivatives is described. The method involves catalytic hydrogenolysis of the corresponding 5-phosphorylated derivatives; products are obtained in high yields.Supported by PHS Grant No. 5429-16-9. 相似文献
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M. Salvini M. Durante L. Citti R. Nobili 《Cellular and molecular life sciences : CMLS》1984,40(12):1401-1403
Summary Brief report on the presence of 5-methyl-cytosine as a minor base (0.56%) in the macronuclear DNA of the ciliate orotozoanBlepharisma japonicum. The evidence comes from electrophoresis of macronuclear DNA digested by appropriate restriction endonucleases and high-performance liquid chromatography 相似文献
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Summary In the sandal plant affected by spike disease, caused by mycoplasma-like organisms, the changes occurring in the 5-and 3-nucleotidase activities were studied and their possible significance discussed. 相似文献
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Laura Pecci S. Duprè A. Antonucci D. Cavallini 《Cellular and molecular life sciences : CMLS》1980,36(8):910-911
Summary Pyridoxal-5-phosphate (PLP) reacts with -carboxyglutamic acid (Gla) to form a stable complex absorbing at 325 nm. It is suggested that a condensation occurs in which the formyl group of PLP reacts with the -amino group and the carbon atom of Gla to give a pyrrolidine derivative. 相似文献
5.
Summary Endogenous levels of adenosine 3,5-cyclic monophosphate (cAMP) in maize (cv. LG 11) root cells, grown in light and dark conditions, were found to be 309 and 387 pmoles/g of fresh tissue respectively.This investigation was partially supported by USA National Science Foundation grant No. CDP 8004200 to the senior author. 相似文献
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Zusammenfassung Die Injektion von N6-2-O-Dibutyryl-adenosin-3 5-monophosphat in den lateralen Hirnventrikel von Kaninchen führt zu einer langanhaltenden Fieberreaktion, was vermuten lässt, dass zyklisches Adenosin-35-monophosphat als weiterer Mediator in der Genese des Fiebers fungiert. 相似文献
7.
M. Hasan 《Cellular and molecular life sciences : CMLS》1977,33(4):552-553
Summary A rapid accurate method for histochemical localization of zinc in the rat brain, utilizing 2-carboxy-2-hydroxy-5-sulfoformazylbenzene perfusion-staining, is described.Acknowledgment. The author is grateful to Dr S. H. Zaidi, Director, I.T.R.C., Lucknow, for permission to use the atomic absorption spectrophotometer and to Mr M. I. Siddiqi, Mr M. Z. Hasan, Mr Mujir and Mr B. Z. K. Sherwani for the technical assistance. 相似文献
8.
Although dipyridamole has been extensively studied as an anti-aggregating agent, its mechanism of action has not been elucidated. Cultured mesangial cells were treated with dipyridamole 1–100 M from 6–72 h. Ecto-5-nucleotidase activity approximately doubled (from 115±11 to 226±14 nmol/min/mg) after treatment with 100 M dipyridamole for 72 h. This effect was concentration- and time-dependent. Cycloheximide, an inhibitor of protein synthesis, did not alter basal 5-nucleotidase activity. However, it prevented stimulation by 5 M dipyridamole. Adenosine availability at the receptor sites was increased by dipyridamole and S-(p-nitrobenzyl)-6-thioinosine (NBTI), which inhibit adenosine uptake into the cell. Addition of dipyridamole or NBTI to the adenosine-treated mesagial cells produced an additive increase in ecto-5-nucleotidase activity. Dipyridamole, through its effect on extracellular adenosine and ecto-5-nucleotidase, may have an influence upon regulation of the glomerular microcirculation. 相似文献
9.
Evidence for essential catalytic determinants for human erythrocyte pyrimidine 5′-nucleotidase 总被引:1,自引:0,他引:1
Amici A Ciccioli K Naponelli V Raffaelli N Magni G 《Cellular and molecular life sciences : CMLS》2005,62(14):1613-1620
Human erythrocyte pyrimidine 5′-nucleotidase, PN-I, catalyzes the dephosphorylation of pyrimidine nucleoside monophosphates. The enzyme also possesses phosphotransferase activity, transferring phosphate groups between pyrimidine nucleoside monophosphates and various pyrimidine nucleosides. Deficiency of the enzyme activity is associated with a hemolytic anemia. PN-I cDNA has been expressed in Escherichia coli, yielding a fully active recombinant enzyme, which was purified to homogeneity and extensively characterized. Multiple sequence alignment of PN-I and homologues proteins revealed the existence of conserved regions, whose importance in catalysis was examined by performing experiments designed to intercept covalent intermediates as strongly suggested by our previous kinetic studies. Furthermore, a functional analysis of the enzyme was carried out through site-directed mutagenesis designed on the basis of the sequence of the identified conserved regions as well as mutations observed in PN-I-deficient patients.Received 25 March 2005; received after revision 3 May 2005; accepted 13 May 2005 相似文献
10.
Summary The o-nitrobenzylester of guanosine 3,5-phosphate is prepared and the photolysis studied. This photoactive form of cGMP should be an agent capable of altering the intracellular concentration of cGMP through membrane penetration and subsequent photolysis.Acknowledgments. We would like to thank the Deutsche Forschungsgemeinschaft and the Universität Konstanz for kindly supporting this research. 相似文献
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T. Kagimoto K. Shirono T. Higaki T. Oda H. Matsuzaki K. Nagata T. Nakaji Y. Morino K. Takatsuki 《Cellular and molecular life sciences : CMLS》1986,42(1):69-72
Summary We describe here a further Japanese family with pyrimidine 5-nucleotidase (P5N) deficiency diagnosed using a nuclear magnetic resonance (NMR) spectrum, in Kumamoto prefecture where two families having the disease have been reported before. The specific spectra in1H-NMR of P5N deficient erythrocytes were due to three methyl protons of CDP-choline at 3.22 ppm and to H-2, H-8 and ribose-1 of pyrimidine nucleotide phosphate(s) in the lower fields (at 5.82 and 8.00 ppm). The other specificities in31P-NMR spectra were due to CDP-choline, CDP-ethanolamine and UDP-glucose. Those spectra were not detected in other types of hemolytic anemia. 相似文献
14.
Summary Unconjugated and conjugated bile salts inhibited the conversion of thyroxine to 3,3,5 triiodothyronine in rat liver homogenate.This work was supported in part by a grant from the Imanaga Foundation, Nagoya, Japan. 相似文献
15.
A. A. Hakim 《Cellular and molecular life sciences : CMLS》1979,35(10):1378-1380
Summary Cyclic-AMP-dependent protein kinase activity was depressed in whole spleen as well as in isolated splenic lymphocytes from 3-methylcholanthrene (MCA), R3230 AdCa mammary adenocarcinoma, N-hydroxy-2-acetylaminofluorene, and 4-dimethylaminoazobenzene (DMAAB) tumor-bearing Fischer rats as compared to control animals. The magnitude of depression increased with the immunogenicity of the tumor. The depressed enzyme activity was the result of a reduced Vmax for adenosine 3,5-monophosphate (cAMP)-stimulated histone phosphorylation. 相似文献
16.
N. Maeda K. Kon M. Sekiya T. Shiga 《Cellular and molecular life sciences : CMLS》1979,35(9):1245-1246
Summary Pyridoxal 5-phosphate is easily incorporated into ACD-stored erythrocytes without decrease of ATP, and restores the poor oxygen transport function with a similar effect to 2,3-diphosphoglycerate. 相似文献
17.
Summary Using a pulse-labeling technique,14C-adenosine uptake into pyrimidine 5-nucleotidase (P5N) deficient erythrocytes (RBC) was found to be impaired. The Lineweaver-Burk plot showed Km values of 2.0×10–3 mM and 0.2 ×10–3 mM for normal RBC and P5N deficient RBC, respectively. These results indicate that P5N is one of regulators of the adenosine transport system and/or is associated with adenosine carrier protein. 相似文献
18.
Summary Liver membrane adenylate cyclase activity was significantly higher and 5-nucleotidase activity significantly lower in alloxan diabetic rats compared with normal rats. 相似文献
19.
V. Ralevic P. Milner K. A. Kirkpatrick G. Burnstock 《Cellular and molecular life sciences : CMLS》1992,48(1):31-34
Adenosine 5-triphosphate (ATP) was released into the perfusate of rat isolated mesenteric arterial beds during each of two consecutive increases in flow. There was no significant difference between the amounts of ATP released on each occasion. Substance P was also released into the perfusate by increased flow, although its release was more variable. Removal of the endothelium of the mesenteric vessels with sodium deoxycholate led to a significant reduction (74%) in the amount of ATP released compared with the release before the endothelium had been removed. This suggests that the ATP released into the mesenteric arterial perfusate during increased flow arises from endothelial cells. 相似文献
20.
Summary In synthesizing 6-(4-pyridyl)-3-mercapto-1,2,4-tria-zin-5-one from the oxime of 4-pyridyl-glyoxylic acid, isonicotinaldehyde-thiosemicarbazone is obtained through decarboxilation as a by-product, which is mainly responsible for the tuberculostatic properties. 相似文献