共查询到20条相似文献,搜索用时 781 毫秒
1.
Sara Schiller 《Biochimica et Biophysica Acta (BBA)/General Subjects》1976,451(2):457-464
- 1. 1. Particulate fractions of costal cartilage from young rats are capable of catalyzing the formation of the first two monosaccharide units of the chondroitin sulfate-protein linkage region.
- 2. 2. Hormonal imbalance has been shown to influence the activity of the glycosyltransferases responsible for the sequential transfer of xylose and galactose from UDPxylose and UDPgalactose, respectively, in the formation of the linkage region.
- 3. 3. The activity of xylosyltransferase was found to be decreased in costal cartilage of diabetic, thyroidectomized and hypophysectomized rats, but not in rats injected with either testosterone or hydrocortisone. In the latter two treatment groups, galactosyltransferase activity was decreased only in the group receiving hydrocorsitone.
- 4. 4. The combined results of this and previous studies suggest that decreased levels of chondroitin sulfate in diabetic, thyroidectomized and hypophysectomized animals are due to interference in the synthesis of the linkage region of the proteoglycan at the xylosyltransferase level whereas hydrocortisone acts primarily at the level of the galactosyltransferase.
Abbreviations: P-ado-P-S; 3′-phosphoadenosine-5′-phosphosulphate 相似文献
2.
Daisuke Kaga Noriaki Minakawa Akira Matsuda 《Nucleosides, nucleotides & nucleic acids》2013,32(10-12):1789-1800
The synthesis of 2′-C-methyl-4′-thiocytidine (16) is described. Since the 2′-keto-4′-thiocytidine derivative 2β unexpectedly isomerized to 2α and the methylation of 2β proceeded predominantly from the less hindered α-face to give 7, the desired product 16 was synthesized via the Pummerer reaction of the sulfoxide 14 and N 4 -benzoylcytosine. 相似文献
3.
4.
5.
6.
Tatsuo Yagura Tomoko Kozu Takeshi Seno Yoshikazu Nishijima Eiko Ohtsuka Morio Ikehara 《Biochemical and biophysical research communications》1982,104(4):1189-1195
DNA polymerase α1, a subspecies of DNA polymerase α of Ehrlich ascites tumor cells, was associated with a novel RNA polymerase activity and utilized poly(dT) and single-stranded circular fd DNA as a template without added primer in the presence of ribonucleoside triphosphates and a specific stimulating factor. DNA synthesis in the above system was inhibited by the ATP analogue, 2′-deoxy-2′-azidoadenosine 5′-triphosphate more than the DNA synthesis with poly(dT)·oligo(rA) by DNA polymerase α1 and RNA synthesis by mouse RNA polymerases I and II. Kinetic analysis showed that the analogue inhibited DNA polymerase α1 activity on poly(dT) competitively with respect to ATP, suggesting that the analogue inhibited RNA synthesis by the associated RNA polymerase activity. 相似文献
7.
8.
S Watabe A Terada T Ikeda H Kouyama S Taguchi N Yago 《Biochemical and biophysical research communications》1979,89(4):1161-1167
Bovine spleen cathepsin D is activated by polyphosphate anions when bovine serum albumin is used as substrate at pH 4.6. In the presence of ATP at 10 mM, the catheptic activity at this pH is enhanced as high as 17 times over the control. Similar activating effects were observed, though to varying degrees, with sodium tripolyphosphate, nucleotides, nucleotide analogues, CoA, polyU and yeast RNA. The possible mechanism and biological significance of the activation were discussed with regard to the intralysosomal polyanionic substance. 相似文献
9.
Metabolism to methionine and growth stimulation by 5'-methylthioadenosine and 5'-methylthioinosine in mammalian cells 总被引:1,自引:0,他引:1
D A Carson E H Willis N Kamatani 《Biochemical and biophysical research communications》1983,112(2):391-397
Viable human and murine lymphoblasts, and normal human tissue extracts, converted the thioether nucleosides 5'-methylthioadenosine (MeSAdo) and 5'-methylthioinosine (MeSIno) to methionine. Both MeSAdo and MeSIno, but not homocysteine, supported the short-term growth of human or murine lymphoblasts in methionine deficient medium. However, MeSAdo at concentrations greater than 25 microM inhibited cell growth. MeSIno was non-toxic at concentrations up to 200 microM, and supported the long-term growth of lymphoblasts in methionine-free medium. 相似文献
10.
Han Yueh Hongchuan Yu Christopher S. Theile Ayan Pal Allen Horhota Nicholas Greco 《Nucleosides, nucleotides & nucleic acids》2013,32(9):661-679
Here, we present efficient syntheses of the R and S diastereomers of 8,5′-cyclo-2′-deoxyadenosine and 6,5′-cyclo-2′-deoxyuridine. We incorporated these interesting nucleosides into DNA to study how the cyclo linkage affects the stability of duplex formation. 相似文献
11.
12.
Six 2′-hydroxyflavonols were isolated from Gutierrezia microcephala, including four new compounds, 5,7,2′-trihydroxy-3,6,4′,5′-tetramethoxyflavone, 5,7,2′-trihydroxy-3,6,8,4′,5′-pentamethoxyflavone, 5,2′-dihydroxy-3,6,7,8,4′,5′-hexamethoxyflavone and 5,7,2′,4′-tetrahydroxy-3,8,5′-trimethxoyflavone and two known compounds, 5,7,2′,5′-tetrahydroxy-3,6,8,4′-tetramethoxyflavone and 5,7,2′,4′-tetrahydroxy-3,6,8,5′-tetramethoxyflavone. 相似文献
13.
R Okazaki S Hirose T Okazaki T Ogawa Y Kurosawa 《Biochemical and biophysical research communications》1975,62(4):1018-1024
The 5′-OH end of DNA created upon alkaline hydrolysis of the RNA-linked nascent DNA pieces can be labeled with [γ-32P]ATP using T4 polynucleotide kinase. However, it is difficult to use this method for the assay of these molecules in the presence of RNA-free DNA pieces because of the exchange reaction between the γ-phosphate of ATP and the 5′-phosphate of DNA catalyzed by the kinase. This difficulty can be circumvented by performing the polynucleotide kinase reaction at 0°C, where little exchange reaction occurs. Using these conditions, Aexl, a mutant defective in the 5′ → 3′ exonuclease activity of DNA polymerase I, is shown to contain several times as many RNA-linked DNA pieces as the wild type. 相似文献
14.
15.
16.
The sarcolemmal membranes isolated from rat skeletal muscle are capable of incorporating 32P from [γ?32P]ATP. The membrane protein phosphorylation requires Mg2+. Cyclic AMP, cyclic GMP and their dibutyrul derivatives showed no marked effect on sarcolemmal phosphorylation.The Mg2+-dependent 32P labeling was significantly enhanced by Na+. The rate of Na+ -stimulated 32P incorporation was quite rapid reaching steady state levels within 5 s at 0 °C. K+ reduced the Na+ -stimulated 32P-incorporation but enhanced the 32Pi release. This inhibitory effect of K+ on Na+ -stimulated 32P incorporation was prevented by the cardiac glycoside, ouabain.The Na+ -dependent 32P labeling showed substrate dependency and the Na+ site was saturable. The apparent for ATP was 2 · 10?5 M. The optimum pH for 32P labeling was between 7 and 8.Na+ -dependent membrane phosphorylation showed a direct relationship with the (Na+ + K+ATPase activity. The high turnover rate of 32P intermediate (12 000 min ?1) suggested its functional significance in the overall transport ATPase reaction sequence.The predominate portion (> 90%) of the phosphorylated membrane complex was sensitive to acidified hydroxylamine and to alkaline pH suggesting an acylphosphate nature of the phosphoprotein.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that 32P incorporation occurred predominately into a 108 000 dalton subunit which is a major protein component of sarcolemmal membranes. A very low level of 32P incorporation was also observed into a 25 000 dalton subunit and Ca2+ slightly enhanced the phosphorylation of this component.The size () and some properties of the sarcolemmal phosphoprotein are closely similar to other (Na+ + K+ATPase preparations reported so far. 相似文献
17.
Estimations of membrane potentials in Streptococcus faecalis by means of a fluorescent probe 总被引:12,自引:0,他引:12
Membrane potentials in were estimated by means of the fluorescent probe, 1,1′-dihexyl-2,2′-oxycarbocyanine. In the absence of D-glucose the potential was ?60 to ?70 mV for normal cells suspended in 0.09 M NaCl + 0.01 M Tris-HCl at pH 7.5. When metabolism was initiated by the addition of D-glucose the cells became hyperpolarized (internal becomes more negative). The new potential, ?130 to ?140 mV, was fully manifested 35 seconds after the glucose was added. N,N′-dicyclohexylcarbodiimide, a membrane ATPase inhibitor prevented the hyperpolarization seen upon the addition glucose. The results are consistent with the view that glycolyzing cells generate a considerasble electrical potential across the cell membrane. 相似文献
18.
The 2′,3′-dialdehyde of ADP, obtained by periodate oxidation of ADP, inhibited the hydrolytic activity of the purified Ca2+, Mg2+-activated ATPase of . In the initial stages of the reaction inhibition was due to the reaction of 1 mol inhibitor/active site. When non-specific labelling of amino groups by the dialdehyde was lowered by the simultaneous presence of 15 mM ATP in the reaction mixture, 3 mol “ATP-protectable” binding sites/mol ATPase were found. “ATP-protectable” binding of the dialdehyde was not observed when the hydrolytically inactive ATPase of an mutant of was used although binding of the inhibitor to non-protected amino groups still occurred. This suggests that the mutant ATPase is unable to bind ATP or that the amino groups with which the dialdehyde reacts in the native enzyme are absent or masked. 相似文献
19.
The disulfonic stilbene (4-acetamido-4′-isothiocyano-2,2′-disulfonic stilbene) is found to be more potent than acetazolamide as an anion transport inhibitor in the turtle bladder, but less potent than acetazolamide as a carbonic anhydrase inhibitor. The anion-dependent (HCO3-−, Cl−) moeity of the short-circuiting current is eliminated by 4-acetamido-4′-isothiocyano-2,2′-disulfonic stibene, but only after its addition to the serosal bathing fluid. Whereas 4-acetmido-4′-isothiocyano-2,2′-disulfonic stilbene has no effect om Na+transport across the bladder, it is more potent than ouabain as an inhibitor of microsomal (Na++K+)-ATPase of both turtle bladder and eel electric organ. 相似文献
20.
From the leaves of Myrica gale 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone has been isolated. The fruits yielded 2′-hydroxy-4′,6′-dimethoxy-3′-methyldihydrochalcone. The constitutions were deduced from spectroscopic data and confirmed by synthesis. 相似文献