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101.
Purification and characterization of nucleoside diphosphatase from rat-liver microsomes. Evidence for metalloenzyme and glycoprotein 总被引:3,自引:0,他引:3
Nucleoside diphosphatase was purified from rat liver microsomes more than 3000-fold with a 16% yield using a procedure including concanavalin-A--Sepharose and phenyl-Sepharose column chromatography. The purified enzyme had a specific activity of 2500 units/mg protein and appeared homogeneous by gel electrophoresis. The enzyme had a sedimentation coefficient of 6.5 S by sucrose-density gradient centrifugation. The enzyme had a sedimentation coefficient of 6.5 S by sucrose-density gradient centrifugation, and a Stokes' radius of 4.8 nm was estimated by the gel filtration technique. Its molecular weight is 130,000, but only one single band of Mr 65,000 was detected after sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The native enzyme seems thus to be composed of two identical subunits. The purified enzyme was confirmed to be a glycoprotein containing approximately 9% carbohydrates. The enzyme had a pH optimum of 7.5, an isoelectric point of 4.85 and a Km of 2.5 mM for UDP. On the basis of direct measurement of metal content in the native enzyme, the rat liver nucleoside diphosphatase was found to be a metalloenzyme containing 0.9 mol zinc and 0.1 mol manganese/mol 65,000-Mr subunit. Metal-free nucleoside diphosphatase has been prepared. The activity of the metal-free enzyme was restored by the addition of several divalent cations, zinc being the most effective. 相似文献
102.
Yuji Kamiya Akira Sakurai Nobutaka Takahashi 《Biochemical and biophysical research communications》1980,94(3):855-860
Rhodotorucine which induces mating tube formation of cells in is metabolized rapidly by cells. By use of labeled rhodotorucine , the degradation was found to be proteolytic. Two peptide fragments Tyr-Pro-Glu-Ile-Ser-Trp-Thr-Arg and Asn-Gly-Cys(S-farnesyl) were identified as the metabolites. Proteolysis of the pheromone mainly occurred on the cell surface. Culture filtrate of cells at log phase did not metabolize rhodotorucine . 相似文献
103.
Katsumi Ajisaka Yuji Iwashita 《Biochemical and biophysical research communications》1980,97(3):1076-1081
Human hemoglobin was modified with polyethylene glycols. The conjugates exhibited P50 values of 10–15 mmHg, those are enough to deliver oxygen from the lungs to tissues. The most remarkable characteristic is their long half disappearance time from the circulation. The longest half disappearance time of these derivatives is about 180 minutes in contrast to 45 minutes of free hemoglobin. The half disappearance time shows a good corelation not to molecular weight but to the effective molecular size, which is determined by the elution time of HPLC on a gel permeation column. 相似文献
104.
Yuji Inada Yukio Tazawa Attula Attygalle Yuji Saito 《Biochemical and biophysical research communications》1980,96(4):1586-1591
Four enzymes in urea cycle and inorganic pyrophosphatase were immobilized simultaneously into a matrix of fibrin fiber formed from fibrinogen by the concerted action of thrombin and blood coagulation Factor XIII. The immobilized multienzyme system not only had an ability to carry out urea cycle continuously at least over several hours, but also had a greatly improved efficiency over the corresponding soluble system. 相似文献
105.
Y Otsuki K Yamaji O Tanizawa M Fujita K Kurachi K Ishibashi K Miyai 《Endocrinologia japonica》1979,26(6):687-691
A practical method was developed for enzyme-immunoassay of serum estriol, with alkaline-phosphatase as a marker enzyme. Alkaline-phosphatase was conjugated with estriol-6-(O-carboxymethyl) oxime using water soluble carbodiimide. The estriol-alkaline-phosphatase complex, which has both enzyme activity and capacity to bind anti-estriol serum, was obtained by Sephadex G-200 gel filtration. This complex, which was stable for at least 3 months at 4 degrees C, was used as enzyme-labelled estriol. Anti-estriol serum raised against estriol-6-(O-carboxymethyl) oxime bovine serum albumin was employed. "Bound and free" estriol were separated by the double antibody method. A linear relation was obtained between estriol concentration and antibody-bound alkaline-phosphatase activity in the range of 0.2-100 ng estriol/ml. In this assay system, cross-reactivity with other steroids was negligible under physiological conditions, and endogenous alkaline-phosphatase, which increases during the late pregnancy, caused no interference. The coefficients of variation were 3.3-14.2% (within assays), and less than 22% (between assays), and the mean recovery rate was 77.5%. Serum estriol values determined by the present method correlated well with those determined by radioimmunoassay (r=0.90 for total estriol; r=0.98 for free estriol). The present method of enzyme-immunoassay is suitable for measurement of serum estriol during pregnancy. 相似文献
106.
Pritam Singh Graeme B. Russell Yuji Hayashi Rex T. Gallagher Susan Fredericksen 《Entomologia Experimentalis et Applicata》1979,25(2):121-127
The effects on housefly (Musca domestica) of six norditerpene lactones (nagilactones B, D, E, podolide, hallactone B and 14-epi-ponalactone A) in a defined diet were tested. Nagilactone D was the most active, with an LD50 of 0.7 ppm. Nagilactones C and D were also toxic to light-brown apple moth (Epiphyas postvittana) and codling moth (Laspeyresia pomonella).The relationship between lactone structure and toxicity to housefly is discussed.
Zusammenfassung Viele aus Podocarpus-Arten isolierte Norditerpenlactone sind für Stubenfliegen toxisch. Es wird über die Resultate der Fütterung von sechs Lactonen an die Stubenfliege in einem definierten Nährboden berichtet und die LD50 von zwölf Verbindungen werden verglichen. Der aktivste Stoff ist Nagilacton mit einer LD50 von 0,7 ppm. Nagilacton C und D sind auch toxisch für Epiphyas postvittana und für den Apfelwickler. Die wirksamsten Verbindungen haben eine kurze nichtpolare Seitenkette und eine elektronenreiche, funktionelle Gruppe bei C-8, ferner sind sie Epoxyalkohole in Ring-A. Diese in der Natur vorkommenden Lactone spielen wahrscheinlich eine Schutzrolle in der Pflanze.相似文献
107.
108.
The addition of glucagon (10?6 M) to an incubation mixture containing 32Pi and hepatocytes isolated from livers of rats fed results in both a 3-fold increased incorporation of 32P into L-type pyruvate kinase and a decreased catalytic activity. The 32P incorporated into pyruvate kinase was covalently bound to the enzyme as evidenced by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. In addition, exogenous cyclic AMP (10?3 M) stimulated the phosphorylation and the suppression of catalytic activity to a similar extent. On the other hand, insulin (10?7 M) had essentially no effect on the incorporation of 32P into pyruvate kinase or on its catalytic activity under the conditions used in this study. These results suggest that phosphorylation of pyruvate kinase is stimulated by glucagon via cyclic AMP and cyclic AMP-dependent protein kinase and that the activity of the enzyme is, at least in part, regulated by a phosphorylation-dephosphorylation mechanism. 相似文献
109.
110.