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61.
Anti-anabolic effects of adenosine 3′:5′-cyclic monophosphate. Inhibition of protein synthesis 总被引:2,自引:1,他引:1
Anthony Sellers David P. Bloxham Kenneth A. Munday Muhammad Akhtar 《The Biochemical journal》1974,138(3):335-340
1. Evidence is presented that cyclic AMP inhibits the incorporation of l-[4,5-(3)H]leucine into protein in a cell-free system from rat liver. This inhibition occurs after aminoacyl-tRNA formation. 2. Microsomal fractions, isolated after the incubation of postmitochondrial supernatant with cyclic AMP and ATP, show a diminished ability to synthesize protein. Both cyclic AMP and ATP are required for this effect. 3. A possible physiological role for the anti-anabolic action of cyclic AMP is discussed in terms of the control of gluconeogenesis. 相似文献
62.
Tetsuya Tosa Tadashi Sato Takao Mori Yuhsi Matuo Ichiro Chibata 《Biotechnology and bioengineering》1973,15(1):69-84
Various methods were tried for the immobilization of aspartase, and the preparation having the highest activity was obtained when partially purified aspartase from Escherichia coli was entrapped into polyacrylamide gel Iattice. Enzymatic properties of the immobilized aspartase were investigated and compared with those of the native aspartase. With regard to optimum pH, temperature, concentration of Mn++, kinetic constants and heat stability, no marked difference was observed between the native and immobilized aspartases. By employing an enzyme column packed with the immobilized aspartase, conditions for continuous production of L -aspartic acid from ammonium fumarate were investigated. When a solution of 1M ammonium fumarate (pH 8.5, containing 1mM MnCl2) was passed through the aspartase column at the flow rate of SV = 0.08 at 37°C, the highest rate of reaction was attained. From the column effluents, L-aspartic acid was obtained in a good yield. 相似文献
63.
64.
Exchange of Genetic Material between Salmonella Typhimurium and Escherichia Coli K-12 总被引:10,自引:0,他引:10 下载免费PDF全文
Tadashi Miyake 《Genetics》1962,47(8):1043-1052
65.
FINE STRUCTURE OF SPINY SPORES OF STREPTOMYCES 总被引:1,自引:0,他引:1
66.
ELECTRON MICROSCOPY OF VIRUS-INFECTED YEAST CELLS 总被引:1,自引:0,他引:1
67.
68.
The conversion of cholest-7-en-3beta-ol into cholesterol. General comments on the mechanism of the introduction of double bonds in enzymic reactions 总被引:6,自引:6,他引:0 下载免费PDF全文
Convenient syntheses of 6β-tritiated Δ7-cholestenol and 3α-tritiated Δ7-cholestene-3β,5α-diol are described. It was shown that the conversion of 6β-tritiated Δ7-cholestenol into cholesterol is accompanied by the complete retention of label. It was unambiguously established that the overall reaction leading to the introduction of the double bond in the 5,6-position in cholesterol occurs via a cis-elimination involving the 5α- and 6α-hydrogen atoms and that during this process the 6β-hydrogen atom remains completely undisturbed. Metabolic studies with 3α-tritiated Δ7-cholestene-3β,5α-diol revealed that under anaerobic conditions the compound is not converted into cholesterol. This observation, coupled with the previous work of Slaytor & Bloch (1965), is interpreted to exclude a hydroxylation–dehydration mechanism for the origin of the 5,6-double bond in cholesterol. It was also shown that under aerobic conditions 3α-tritiated Δ7-cholestene-3β,5α-diol is efficiently converted into cholesterol and that this conversion occurs through the intermediacy of 7-dehydrocholesterol. Cumulative experimental evidence presented in this paper and elsewhere is used to suggest that the 5,6-double bond in cholesterol originates through an oxygen-dependent dehydrogenation process and a hypothetical mechanism for this and related reactions is outlined. 相似文献
69.
The stereochemistry of the hydrogen elimination in the biological conversion of cholest-7-en-3β-ol into cholesterol 总被引:5,自引:5,他引:0 下载免费PDF全文
1. The syntheses of Δ7-[4-14C]cholestenol (XVI, Scheme 3) and Δ7-[6α-3H]-cholestenol (XII, Scheme 2) are described. 2. The metabolism of doubly labelled Δ7-cholestenol (II, Scheme 1) by rat-liver homogenates was studied. 3. During the enzymic conversion of Δ7-cholestenol into cholesterol (IV, Scheme 1) the 6α-hydrogen atom of the former is lost and the overall reaction corresponds to a cis-elimination. 4. In the light of these results various mechanisms for the conversion of Δ7-cholestenol into cholesterol are discussed. 相似文献
70.
Identification of membrane anchoring site of human renal dipeptidase and construction and expression of a cDNA for its secretory form 总被引:1,自引:0,他引:1
H Adachi T Katayama C Inuzuka S Oikawa M Tsujimoto H Nakazato 《The Journal of biological chemistry》1990,265(25):15341-15345
The chemical properties of human renal dipeptidase (hrDP) purified from the membrane fraction of kidney have been characterized. When treated with phosphatidylinositol-specific phospholipase C, hrDP was released from renal membrane fractions. After digestion with trypsin, carboxyl-terminal peptide was isolated employing anhydrotrypsin-agarose column chromatography and reversed-phase high performance liquid chromatography. The amino acid sequence of the peptide was identified at positions 363-369 in the primary structure deduced from the cDNA sequence (Adachi, H., Tawaragi, Y., Inuzuka, C., Kubota, I., Tsujimoto, M., Nishihara, T., And Nakazato, H. (1990) J. Biol. Chem. 265, 3992-3995). Further examination of the chemical composion of the peptide showed that it contained, respectively, 2, 1, 5, 1, and 1 mol of ethanolamine, glucosamine, mannose, inositol, and phosphate in addition to amino acids. These results suggest that the mature hrDP molecule lacks the carboxyl-terminal hydrophobic peptide extension predicted from the cDNA sequence and is anchored at Ser369 via glycosylphosphatidylinositol to the membrane. To characterize further the action of the enzyme, we have established expression systems for both secretory and membrane anchored forms of hrDP using COS-1 cells and found that both recombinant forms were as active as natural enzyme. Our expression system made it possible to prepare large amounts of soluble enzyme, and will contribute toward elucidation of the physiological roles of the enzyme. 相似文献