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61.
Differential regulation of basic protein phosphorylation by calcium phospholipid and cyclic-AMP-dependent protein kinases 总被引:2,自引:0,他引:2
Myelin basic protein, an 80-kilodalton (kDa) protein in rat oligodendrocytes, and an 80-kDa basic protein in neuroblastoma x neonatal Chinese hamster brain explant hybrids were phosphorylated extensively when the cells were treated with either phorbol esters (TPA) or diacylglycerols (e.g., oleyoyl-acetylglycerol). TPA-stimulated phosphorylation was inhibited by pre-incubation with 50 microM psychosine (galactosyl-sphingosine), confirming that it is mediated through the phospholipid-dependent protein kinase C (PK-C). Surprisingly, phosphorylation of these proteins was inhibited by incubation of cells with agents which result in activation of cyclic-AMP-dependent protein kinase (dibutyryl cyclic AMP or forskolin). In contrast, phosphorylation of other nonbasic proteins, for example, the oligodendrocyte-specific 2',3'-cyclic nucleotide phosphohydrolase, was stimulated under these conditions (Vartanian et al.: Proceedings of the National Academy of Sciences of the United States of America 85:939, 1988). The possible role of cyclic AMP in activating specific phosphatases or restricting the availability of diacylglycerol for PK-C activation is discussed. 相似文献
62.
63.
Steroid metabolites in urine from neonates with 21-hydroxylase deficiency are predominantly polyhydroxylated 17-hydroxyprogesterone and androgen metabolites, and most have incompletely defined structure. This study forms part of a comprehensive project to characterize and identify these in order to enhance diagnosis and to further elucidate neonatal types of steroid metabolism.Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra, obtained with constant excitation conditions, were used together to determine the structure of the D-ring and the side chain of 20-oxo and 20-hydroxy pregnane(ene)s without oxo groups on the A-, B-, and C-ring.All possible combinations of D-ring and side chain configuration were considered. Most fragmentations could be interpreted as partial or complete D-ring cleavages with loss of the side chain, aided by comparison with spectra of deuterated derivatives and of borohydride reduced metabolites. Possible rearrangement ions are also discussed. More than 140 endogenous metabolites were characterized.GC-MS/MS was especially beneficial for characterization of compounds with 16,17-dihydroxy-20-oxo structure, interpreted as markers of intra-uterine enzyme induction. It also assisted the differentiation of 16-hydroxy-20-oxo metabolites, present in urine of non-affected neonates, from the diagnostic 17-hydroxy-20-oxosteroids and enabled the detection of 15,17-dihydroxy-20-oxo compounds in low concentrations. The presence of 17,21-dihydroxylated pregnane(ene)s despite the deficit in CYP21A2 is discussed.We conclude that GC-MS combined with GC-MS/MS allows reliable identification of the structure of the D-ring and side chain of pregnane(ene)s without prior isolation, even when in low concentrations in urine. 相似文献
64.
《Bioorganic & medicinal chemistry》2016,24(2):240-246
A novel series of indolylthiosemicarbazides (6a–6g) and their cyclization products, 4-thiazolidinones (7a–7g), have been designed, synthesized and evaluated, in vitro, for their antiviral activity against a wide range of DNA and RNA viruses. Compounds 6a, 6b, 6c and 6d exhibited notable antiviral activity against Coxsackie B4 virus, at EC50 values ranging from 0.4 to 2.1 μg/mL. The selectivity index (ratio of cytotoxic to antivirally effective concentration) values of these compounds were between 9 and 56. Besides, 6b, 6c and 6d also inhibited the replication of two other RNA viruses, Sindbis virus and respiratory syncytial virus, although these EC50 values were higher compared to those noted for Coxsackie B4 virus. The SAR analysis indicated that keeping the free thiosemicarbazide moiety is crucial to obtain this antiviral activity, since the cyclization products (7a–7g) did not produce any antiviral effect. 相似文献
65.
66.
《Cell reports》2020,30(5):1530-1541.e4
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67.
Tomohiko J. Itoh Hidemi Sato 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,800(1):21-27
The initial rate and final extent of polymerization of both bovine brain tubulin and sea urchin egg tubulin were enhanced in the presence of 2H2O. The yields were increased in association with the elevation of the 2H2O concentration. 2H2O also reduced the critical concentration for polymerization of brain tubulin. Thermodynamic analysis was attempted using the temperature dependence of the critical concentration for polymerization in the presence of 2H2O. We obtained linear van 't Hoff plots and calculated thermodynamic parameters which were positive and were increased with the elevation of the 2H2O concentration. The enhancement of the polymerization of tubulin by 2H2O could, therefore, be the result of the strenghening of intra-and/or inter-molecular hydrophobic interactions of the tubulin molecules. We believe that the increase in lenghth and number of microtubules of the mitotic spindles in the dividing cells of the eukaryotes with 2H2O may be caused by the direct involvement of 2H2O in the polymerization of tubulin. 相似文献
68.
An examination of four species of Cirsium disclosed the presence of two new flavonoids in C. lineare. The structure of one was 5,4′-dihydroxy-6,7,3′-trimethoxyflavone (cirsilineol) 4′-monoglucoside and the other 5,3′,4′-trihydroxy-6,7-dimethoxyflavone (cirsiliol) 4′-monoglucoside. Luteolin 7-glucoside was found in C. suffultum, and pectolinarin and linarin in C. kamtschaticum and C. pectinellum. 相似文献
69.
Comparison of Karanjin with other nitrification inhibitors for retardation of nitrification of urea N in soil 总被引:1,自引:0,他引:1
K. L. Sahrawat 《Plant and Soil》1981,59(3):495-498
Summary Comparative evaluation of Kranjin and three patented nitrification inhibitors for retardation of nitrification of urea in a sandy clay loam showed that the effectiveness of the compounds tested decreased in the order: Nitrapyrin>Karanjin>A.M.>dicyandiamide. 相似文献
70.
Lina Long Douglas R. McCabe M. Eileen Dolan 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,731(2):128
A highly sensitive and selective method for determining 8-oxoguanine in plasma and urine was developed by high-performance liquid chromatography with electrochemical detection. The compound was separated by gradient elution on a C18 reversed-phase column with a mobile phase of acetonitrile and 0.1 M sodium acetate, pH 5.2. 8-Hydroxy-2′-deoxyguanosine was used as internal standard. 8-Oxoguanine was detected electrochemically by setting the potential to +300 mV vs. Pd reference. The sensitivity of the assay was 22 ng/ml with a signal-to-noise ratio of 7:1. The within-day relative standard deviations for 8-oxoguanine quality control samples with concentrations of 3340, 1340 and 84 ng/ml were 3.6, 4.3 and 5.7% for plasma, and 4.1, 4.6 and 6.2% for urine, respectively. The day-to-day relative standard deviations for the same samples were 3.8, 6.8 and 7.1% for plasma, and 3.9, 7.0 and 7.9% for urine, respectively. The method is designed to study the pharmacokinetics and metabolic fate of O6-benzylguanine in a phase I clinical trial. Previously, O6-benzyl-8-oxoguanine was identified as the primary metabolite of O6-benzylguanine in humans. We now demonstrate that 8-oxoguanine is a further metabolite of O6-benzylguanine. 相似文献