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71.
72.
Yohei Hashimoto Hiroyuki Ishizone Midori Moriyasu Kazuko Kawanishi Atsushi Kato Masaru Ogura 《Phytochemistry》1984,23(8):1807-1808
Three oleanane triterpenes were isolated from the roots of Periandra dulcis,and identified as 3β-hydroxy-25-al-olean-18-en-30-oic acid (periandric acid I), 3β-hydroxy-25-al-olean-12-en-30-oic acid (periandric acid II) and 3-oxo-25-hydroxy-olean-12-en-30-oic acid. The former two compounds (periandric acids I and II) were identical with the aglycones obtained by hydrolysis of periandrin I and II, respectively and the latter one was a new triterpene. 相似文献
73.
Analysis of the energy metabolism after incubation of Saccharomyces cerevisiae with sulfite or nitrite 总被引:1,自引:0,他引:1
After addition of 5 mM sulfite or nitrite to glucose-metabolizing cells of Saccharomyces cerevisiae a rapid decrease of the ATP content and an inversely proportional increase in the level of inorganic phosphate was observed. The concentration of ADP shows only small and transient changes. Cells of the yeast mutant pet 936, lacking mitochondrial F1ATPase, after addition of 5 mM sulfite or nitrite exhibit changes in ATP, ADP and inorganic phosphate very similar to those observed in wild type cells. They key enzyme of glucose degradation, glyceraldehyde-3-phosphate dehydrogenase was previously shown to be the most sulfiteor nitrite-sensitive enzyme of the glycolytic pathway. This enzyme shows the same sensitivity to sulfite or nitrite in cells of the mutant pet 936 as in wild type cells. It is concluded that the effects of sulfite or nitrite on ATP, ADP and inorganic phosphate are the result of inhibition of glyceraldehyde-3-phosphate dehydrogenase and not of inhibition of phosphorylation processes in the mitochondria. Levels of GTP, UTP and CTP show parallel changes to ATP. This is explained by the presence of very active nucleoside monophosphate kinases which cause a rapid exchange between the nucleoside phosphates. The effects of the sudden inhibition of glucose degradation by sulfite or nitrite on levels of ATP, ADP and inorganic phosphate are discussed in terms of the theory of Lynen (1942) on compensating phosphorylation and dephosphorylation in steady state glucose metabolizing yeast.Abbreviations ATP
adenosine triphosphate
- ADP
adenosine diphosphate
- AMP
adenosine monophosphate
- Pi
inorganic orthophosphate
Dedicated to Prof. Dr. Hans Grisebach on the occasion of his sixtieth birthday 相似文献
74.
In intact, uncoupled type B chloroplasts from spinach, added ATP causes a slow light-induced decline () of chlorophyll a fluorescence at room temperature. Fluorescence spectra were recorded after fast cooling to 77 K and normalized with fluorescein as an internal standard. Related to the fluorescence quenching at room temperature, an increase in Photosystem (PS) I fluorescence (F735) and a decrease in PS II fluorescence (F695) were observed in the low-temperature spectra. The change in the ratio was abolished by the presence of methyl viologen. Fluorescence induction at 77 K of chloroplasts frozen in the quenched state showed lowered variable (Fv) and initial (F0) fluorescence at 690 nm and an increase in F0 at 735 nm. The results are interpreted as indicating an ATP-dependent change of the initial distribution of excitation energy in favor of PS I, which is controlled by the redox state of the electron-transport chain and, according to current theories, is caused by phosphorylation of the light-harvesting complex. 相似文献
75.
Monoclonal antibody-directed immunopurification and identification of cytochromes P-450 总被引:4,自引:0,他引:4
F K Friedman R C Robinson S S Park H V Gelboin 《Biochemical and biophysical research communications》1983,116(3):859-865
A 28 amino acid peptide with diuretic and natriuretic activity has been purified from rat atrial muscle. The primary structure of this atrial peptide is H-Ser-Leu-Arg-Arg-Ser-Ser-Cys-Phe-Gly-Gly-Arg-Ile-Asp-Arg-Ile-Gly- (sequence in text) Ala-Gln-Ser-Gly-Leu-Gly-Cys-Asn-Ser-Phe-(Arg)-Tyr-OH. The biological activity of this peptide is identical to that of atrial natriuretic factor and cardionatrin I isolated from rat atria. 相似文献
76.
Abstract: Membranes of the secretory vesicles from bovine adrenal medulla were investigated for the presence of the endogenous protein phosphorylation activity. Seven phosphoprotein bands in the molecular weight range of 250,000 to 30,000 were observed by means of the sodium dodecyl sulphate electrophoresis and autoradiography. On the basis of the criteria of molecular weight, selective stimulation of the phosphorylation by cyclic AMP (as compared with cyclic GMP) and immunoprecipitation by specific antibodies, band 5 (molecular weight 60,300) was found to represent the phosphorylated form of the secretory vesicle-bound tyrosine hydroxylase. The electrophoretic mobility, the stimulatory and inhibitory effects of cyclic AMP in presence of Mg2+ and Zn,2+ respectively, and immunoreactivity toward antibodies showed band 6 to contain two forms of the regulatory subunits of the type II cyclic AMP-dependent protein kinase, distinguishable by their molecular weights (56,000 and 52,000, respectively). Phosphorylation of band 7 (molecular weight 29,800) was stimulated about 2 to 3 times by Ca2+ and calmodulin in the concentration range of both agents believed to occur in the secretory tissues under physiological conditions. 相似文献
77.
Antonio G. Gonzalez Jaime Bermejo Barrera Francisco J. Tolfdo Marante 《Phytochemistry》1983,22(4):1049-1050
The fruit bodies of the Basidiomycete Scleroderma polyrhizum have been shown to contain the steroids ergosta-4,6,8(14) 22-tetraen-3-one and 5α,8α-epidoxyergosta-6,22-dien-3β-ol and also palmitic and oleic acids. 相似文献
78.
Mutations induced by repeated EMS treatments were investigated by using mouse L5178Y cells. The frequency of TGr mutations increased linearly with the number of EMS treatments whereas the yield of BrdUrdr mutations showed a curvilinear dose-response curve. The BrdUrdr frequency was roughly proportional to the square of the TGr frequency and the results were compatible with the hypothesis that BrdUrdr cells were induced by two mutational events within a cell. Most of the BrdUrdr colonies isolated after 6 EMS treatments, however, were unstable. When BrdUrdr colonies that had arisen in BrdUrd medium after 2 weeks' incubation were isolated in normal medium, the descendant cells showed a nearly normal level of thymidine incorporation and low plating efficiencies of about 1% in BrdUrd medium. In contrast, after isolation of the same colonies in BrdUrd medium, a low level of thymidine incorporation and high plating efficiencies in BrdUrd medium were observed in the descendant cells.
Reverse selection from BrdUrdr to HATr was accomplished with frequencies of 10−6−10−3 for the descendants grown in BrdUrd medium, and AzaCyd treatment drastically increased the reversion frequency to nearly 10−1. Further re-revertants from HATr to BrdUrdr were also found with frequencies of 10−3−10−2 without treatment. These results indicate that the initial BrdUrdr cells did not result from inactivation of the thymidine-kinase gene but that the mode of gene expression was altered in some way. 相似文献
79.
The 1H nuclear magnetic resonance (nmr) spectra of complexes of soybean ferric leghemoglobin with 3-substituted pyridines and 5-substituted nicotinic acids have been recorded in order to determine the influence of axial ligands on heme electronic structure. The hyperfine shifted resonances of the heme group were assigned by analogy to previous assignments for the pyridine and nicotinic acid complexes of leghemoglobin. The spectra are characteristic of predominantly low-spin ferric heme complexes. For the pyridine complexes, the rate of ligand exchange was found to increase with decreasing ligand pKA. For many of the complexes, optical and nmr spectra reveal the presence of an equilibrium mixture of high- and low-spin states of the iron atom. The percentage of high-spin component increases with decreasing ligand pKA Smaller hyperfine shifts are noted for leghemoglobin complexes with ligands capable of weak ligand → metal π bonding. The pattern of hyperfine shifted resonances is similar for all complexes studied and indicates that the overall heme electronic structure is dominated by the bonding to the proximal histidine. 相似文献
80.
The suppressive effect of peritoneal exudate macrophages on production of antibody to sheep erythrocytes in vitro 总被引:1,自引:0,他引:1
The effects of peritoneal exudate macrophages on antibody response to sheep erythrocytes (SRBC) were investigated in mice. Peritoneal exudate macrophages obtained from mice injected intraperitoneally with proteose peptone or Corynebacterium parvum 4 days earlier had stronger ability to phagocytize and degrade SRBC than normal resident macrophages. These macrophages suppressed antibody formation to SRBC in vitro as well as in vivo. This suppression was overridden by increasing the amount of SRBC and diminished completely by pretreatment of the macrophages with iodoacetate and partly by pretreatment with 2-deoxyglucose, both known to be inhibitors of phagocytosis, but not by addition of indomethacin to the in vitro culture. These results suggest that the suppression of antibody response by peritoneal exudate macrophages was due to the increased activity of these cells as scavenger cells, resulting in a reduced amount of effective antigenic stimulation, and that it was not mediated by a prostaglandin-dependent mechanism. The scavenger function of these macrophages may be due to Ia-negative macrophages. 相似文献