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1.
Controlled alkaline hydrolysis of 16α-bromo-17-keto steroids , and with potassium carbonate and tetra-n-butylammonium hydroxide (n-Bu4NOH) and synthesis of 2α-hydroxy-3-ones , and by the controlled hydrolysis of the corresponding 2α-bromo-3-ones , and are described. Treatm carbonate in aqueous acetone or with n-Bu4NOH in aqueous dimethylformamide (DMF) gave 16α-hydroxy-17-ones , and in 85–90% yield, respectively. 2α-Hydroxy-3-ones , and were obtained by hydrolysis of the corresponding bromoketones , and in high yields using the above conditions or sodium hydroxide in pyridine or DMF, respectively. Deuterium labeling experiments suggested that equilibration between the 2α-bromoketone and the 2β-bromo isomer precedes the formation of the ketol in which the true intermediate might be the 2β-isomer . However, rearranged androstane derivatives, 3β-hydroxy-2-ones and , were stereoselectively obtained by treatment of the bromoketones and with an excess amount of sodium hydroxide. 相似文献
2.
John W. Kendrick 《Theriogenology》1976,5(3):150-152
and : Herds infected with have histories of infertility, occasional abortions, and pyometra.: There are no specific gross lesions in the fetus. The fetuses are usually aborted in the first half of gestation and may or may not be accompanied by the placenta.: There are no specific microscopic lesions.: It is ordinarily not necessary to culture in order to demonstrate its presence in placental fluids and/or abomasal contents.: There are no suitable seroligic procedures for diagnosing Trichomoniasis.: Wet mounts of abomasal contents and/or placental fluids are examined microscopically for .: Demonstrate the presence of by microscopic examination of wet mounts of placental fluids and/or abomasal contents. 相似文献
3.
The metabolism of drobuline has been examined in the dog, rabbit, rat, guinea pig and hamster. In the dog, unlike the other species, glucuronide conjugation is the major route of metabolism. The structure of the conjugate has been established as an O-glucuronide by isolation using HPLC following by field desorption mass spectral analysis. When the separate - and -isomers of drobuline were administered to a series of dogs the -isomer reached plasma levels approximately three time higher than those of the -isomer. Deuterium labeled drobuline was synthesized and resolved by multiple crystallizations of the malate salts. Racemic mixtures containing 6- and 6- drobuline and 6- and 6- drobuline were prepared and analyzed by GC-MS as the pentafluoropropionate derivatives. When either racemic mixture was administered to dogs (10 mg/kg, p.o.) the plasma levels of the -isomer were found to be approximately three times those of the -isomer. Using these deuterium labeled mixtures the disposition of the two isomers has been examined in the isolated perfused dog liver, in hepatocytes and isolated microsomes. The results indicate that the difference in plasma levels of the - and -isomers is not dependent upon stereospecific absorption or excretion but rather it is caused by metabolism of the -isomer at a faster rate than that of the -isomer. 相似文献
4.
R.S. Foote S. Mitra B.C. Pal 《Biochemical and biophysical research communications》1980,97(2):654-659
6-Methyl[8-3H]deoxyguanosine in a synthetic DNA polymer, poly(dC, dG, m6dG), is demethylated by cell-free extracts of adapted by exposure to -methyl-′-nitro--nitrosoguanidine, as shown by the appearance of 3H-labeled deoxyguanosine in hydrolysates of the recovered DNA. The demethylating activity could not be detected in extracts of nonadapted . These results provide direct evidence that a previously described inducible repair activity in acts by demethylating 6-methylguanine at the DNA level. 相似文献
5.
Fine structure of the recB and recC gene region of Escherichia coli 总被引:14,自引:0,他引:14
M Sasaki T Fujiyoshi K Shimada Y Takagi 《Biochemical and biophysical research communications》1982,109(2):414-422
6.
The replication defective transducing phage λp3 carries a portion of the operon in the 2 region of the lambda phage. This operon segment contains the promoter, the operator, and the β-galactosidase gene, but does not contain the repressor gene. The gene can be expressed from both the inserted promoter and the phage promoter. When strain 594 (?, +) or JC6256 (Δ) is infected by λp3 in the absence of additional cyclic AMP, β-galactosidase synthesis is shown to be expressed from the phage promoter. When 594 (λ+) or JC6256 (λ+) is infected by λp3 in the presence of additional cyclic AMP and IPTG, β-galactosidase synthesis is shown to be expressed from the inserted promoter.The ability to separate the phage promoter from the inserted promoter for β-galactosidase expression will simplify the interpretation whenever λp5 is used. 相似文献
7.
Evelyn A. Devine Mary C. Moran Peter J. Jederlinic Anthony J. Mazaitis Henry J. Vogel 《Biochemical and biophysical research communications》1975,67(4):1589-1593
The transducing phage λd, carrying a portion of the chromosome including , is derived from the heat-inducible, lysis-defective strain λy199, which has the and deletions. Cleavage of λy199 DNA by RI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus minus , the cleavage site between A and B being eliminated). Cleavage of λd DNA by RI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the cluster is on the 14-1 segment. 相似文献
8.
The site of action of the crinkled (cr) locus was determined by combining dermis and epidermis from the tail of 15-day and mice and by growing the recombined skins in the testes of histocompatible mice. Since mice have bald tails, the presence or absence of hair in the graft was the feature used to determine gene action. Grafts of the combinations dermis and dermis grew hair, whereas grafts of the combinations dermis and dermis produced no hair. It was concluded that the cr locus, at least for tail skin, is active in the epidermis. 相似文献
9.
10.
H.R. Bosshard M. Zürrer H. Schägger G. von Jagow 《Biochemical and biophysical research communications》1979,89(1):250-258
Cytochrome 1, the electron donor for cytochrome , is a subunit of the mitochondrial cytochrome 1 complex (complex III, cytochrome reductase). To test if cytochrome 1 is the cytochrome -binding subunit of the 1 complex, binding of cytochrome to the complex and to isolated cytochrome 1 was compared by a gel-filtration method under non-equilibrium conditions (a 1 complex lacking the Rieske ironsulfur protein was used; von Jagow et al. (1977) Biochim. Biophys. Acta , 549–558). The approximate stoichiometries and binding affinities were found to be very similar. Binding of cytochrome to isolated cytochrome which is another subunit of the reductase was not detectable by the gel-filtration method. Further, the same lysine residues of cytochrome were shielded towards chemical acetylation in the complexes 1 and 1. From this we conclude that the same surface area of cytochrome is in direct contact with cytochrome 1 and with cytochrome 1 in the respective complexes and that therefore cytochrome is most probably the structural ligand for cytochrome in mitochondrial cytochrome reductase. 相似文献
11.
In homogenates of (Rhesus) or amygdaloid nuclear complex, adenylate cyclase activity was approximately doubled by either 10μ dopamine or 8m NaF. In the presence of morphine, the stimulation by dopamine was reduced. A 90–100% inhibition of the dopamine stimulation was obtained with 20μ, and a 50% inhibition, with 5μ morphine. The effects of 10μ morphine on dopamine stimulation were reversed by 10μ naloxone. Morphine itself did not significantly affect the basal adenylate cyclase activity, but in the presence of 10μ morphine the stimulation by 8m NaF was reduced approxiamtely 50%. The data suggest an action of morphine at a receptor site which is distinct from the dopamine receptor, but which inhibits the dopamine-stimulated adenylate cyclase. In addition, the cyclic GMP content of amygdala slices was reduced by 50–75% during incubation for 5–20 minutes with morphine. Maximum effects on cyclic GMP were obtained with 10μ, and half-maximum effects, with 0.1μ morphine. The effect of morphine on amygdala cyclic GMP was not reversed by naloxone. Thus, this action of morphine may not be receptor mediated, or may involve the interaction of morphine with receptors other than the opiate receptor. 相似文献
12.
1-Aminoglycosides represent a new class of specific and relatively potent inhibitors of glycosidases. These compounds are specific against those enzymes which act upon glycosides that correspond to glycone of the inhibitor. Thus α- and β-- are inhibited by -glucosidases but not by -galactosylamine and -mannosylamine. α- and -galactosidases are inhibited by -galactosylamine but not by the other two glycosylamines. -Mannosylamine inhibits mannosidase. 相似文献
13.
A Novel function of cytochrome C (555, Chlorobium thiosulfatophilum) in oxidation of thiosulfate 总被引:2,自引:0,他引:2
Thiosulfate-cytochrome c-551 reductase derived from has been highly purified. The enzyme reduces cytochrome in the presence of thiosulfate while cytochrome -555 of the organism is not reduced by the enzyme. Cytochrome -555 reacts with the enzyme at an appreciable rate only in the presence of cytochrome -551. However, the reduction rate of cytochrome -551 by the enzyme is greatly enhanced on addition of a catalytic amount of cytochrome -555. Therefore, cytochrome -555 seems to function as an effector on thiosulfate-cytochrome -551 reductase as well as it acts as the electron donor to the light-excited chlorobium chlorophylls. 相似文献
14.
The synthesis of 4-ethenylidene-5α-androstane-3β, 17β-diol () and of 4-ethenylidene-5α-androstane-3,17-dione () is described. Compound is a competitive inhibitor of solubilized bovine microsomal adrenal Δ5-3β-hydroxysteroid dehydrogenase, with Ki =2.7μM, and is converted by the enzyme to the corresponding 3-ketone. Compound shown to irreversibly inactivate the enzyme in a time-dependent manner (). The substrate, dehydroepiandrosterone, protects against inactivation by compound . In contrast, compound is not oxidized at the 3-position by the 3β-(and 17β)-hydroxysteroid dehydrogenase from , but is oxidized at the 17-position. Nevertheless, the 4-ethenylidene-3,17-diketone () causes irreversible time-dependent inactivation () when incubated directly with this bacterial enzyme, acting as an affinity label. 相似文献
15.
Strand resealing in the excision repair of 5,6-dihydroxy-dihydrothymine in osmium tetroxide oxidized polyd(A-T) by crude extracts is accomplished by polynucleotide ligase. Osmium tetroxide oxidized polyd(A-T)_serves as a chemically well defined model substrate containing damage of the kind introduced into DNA by ionizing radiation. In the first incision step of excision repair approximately one endonucleolytic nick is introduced into the polymer by extracts of endoI? and endoI?A6? per ring damaged thymine residue removed. 相似文献
16.
R.D. Randel 《Theriogenology》1984,21(1):170-185
Reproductive function is mediated by season in the Indian breeds of cattle (). The reproductive endocrinology of cattle differs from that of breeds; the estrus is shorter and less intense and occurs late in relation to an estrogen stimulus. Moreover, the female has a smaller preovulatory surge of luteinizing hormone (LH), which occurs earlier relative to the onset of estrus, and she ovulates sooner after the onset of estrus. The corpus luteum is smaller and contains less progesterone, and the serum progesterone concentration is lower in females. Furthermore, they have fewer preovulatory LH surges than females and their luteal cells are less responsive to LH in vitro during the winter. Their fertility is lower during the late fall and winter months. For cattle, recovery of transferable embryos and survival of embryos in the recipient are at their maximum from July through October. 相似文献
17.
Ward R. Rice Jeffrey A. Whitsett 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,805(3):261-267
Release of [3H]phosphatidylcholine from pulmonary Type II epithelial cells was stimulated by terbutaline, forskolin and cytochalasin D. Compound inhibited both basal and agonist-stimulated release of [3H]PC. The IC50 for inhibition by compound was 1–2 μg/ml, and was similar for inhibition of both basal and stimulated release of [3H]phosphatidylcholine. Inhibitory effects of were noted following a 1 h exposure to compound and persisted up to 3 h. The inhibitory effect of compound was entirely reversed by removing compound from the external milieu. Compound had no effect on cytosolic cyclic AMP levels or lactate dehydrogenase release. Inhibition of surfactant release produced by compound was unaffected by changes in extracellular calcium concentrations. Compound is a non-toxic inhibitor of phosphatidylcholine release from Type II epithelial cells. 相似文献
18.
R B Frydman J Awruch M L Tomaro B Frydman 《Biochemical and biophysical research communications》1979,87(3):928-935
Hemin XIII , hemin III , and iron were enzymatically oxidized by a microsomal heme oxygenase preparation from rat liver. These are all better substrates of the oxygenase than the natural substrate, hemin IX . The enzymatic oxidation was selective for the α-methine bridge and in every case only the α-biliverdins were obtained. The latter were readily reduced by biliverdin reductase to the corresponding α-bilirubins. The absence of isomers in addition to the α-bilirubins was established by preparing the derived azopigments and by using [α-14C] and [α-14C] as substrates. The chemical oxidation of , , and gave the expected mixture of biliverdins. It is concluded that heme oxygenase is not specific for hemin IX. On the other hand, the enzyme is highly selective for the α-methine bridge, defined as the methine opposed to that flanked by the 6,7-propionic acid residues. 相似文献
19.
20.
F Bolívar 《Life sciences》1979,25(10):807-817
recombination via restriction endonucleases and genetic translocation of an impicillin resistance gene, have been utilized for the construction of a series of cloning vehicles. These vectors have been derived by combining the essential replication properties of plasmid pMBl, a CoLEl type plasmid, with one, two or three resistance markers (tetracycline, ampicillin, chloramphenicol and colicin El production). During the construction of these vectors, the position of restriction sites used for cloning DNA fragments, relative to the antibiotic resistance genes and the origin of DNA replication, have been determined. The use of the cloning vectors pMB9, pBR313, pBR322, pBR324, pBR325 permits the molecular cloning and easy selection of RI, HI, II, II, III, I, I, I, I, I, II, I, I, I, l I, I, I, II, III, I, II, RII and virtually any blunt-ended generated DNA fragment. 相似文献