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61.
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
62.
Hiroshi Hayakawa Kanji Ishizaki Masao Inoue Takashi Yagi Mutsuo Sekiguchi Hiraku Takebe 《Mutation research》1981,80(2)
DNA-repair characteristics of xeroderma pigmentosum belonging to complementation group F were investigated. The cells exhibited an intermediate level of repair as measured in terms of (1) disappearance of T4 endonuclease-V-susceptible sites from DNA, (2) formation of ultraviolet-induced strand breaks in DNA, and (3) ultraviolet-induced unscheduled DNA synthesis during post-irradiation incubation. The impaired ability of XP3YO to perform unscheduled DNA synthesis was restored, to half the normal level, by the concomitant treatment with T4 endonuclease V and ultraviolet-inactivated Sendai virus. It is suggested that xeroderma pigmentosum cells of group F may be defective, at least in part, in the incision step of excision repair. 相似文献
63.
Yoshinori Asakawa Masao Toyota Reiji Takeda Claude Suire Tsunematsu Takemoto 《Phytochemistry》1981,20(4):725-728
Riccardia species (Metzgeriales) contain various types of sesquiterpenes. R. jackii produces ent-selinane-, ent-aromadendrane-and ent-bicyclogermacrane-type sesquiterpenes together with (R)-cuparene and α-barbatene. Aneura pinguis (= Riccardia pinguis) is chemically quite different from R. multifida and R. jackii. The former produces a large amount of pinguisone. R. multifida contains 6-(3-methyl-2-butenyl)-indole and (+)-β-elemene as the major components. Pallavicinia longispina (Dilaenaceae; Metzgeriales) produces mainly spathulenol. The chiral properties of the sesquiterpenes isolated from R. jackii are quite similar to those of red algae, Laurencia species. 相似文献
64.
A new bibenzyl having a dihydrooxepin ring was isolated from the acetone extract of the liverwort Radula tokiensis, together with the previously known 5 bibenzyls and 3 sesquiterpenes, trans-β-farnesene, cuparene and (Jcuparenol. Two known bibenzyls were isolated from R. japonica. The bibenzyl derivatives are significant chemosystematic markers of the Radulaceae. 相似文献
65.
Cells ofClosterium ehrenbergii expanded for about 4.5 hr after vegetative cell division and about 3 hr after sexual cell division. Short cells were produced by the sexual expansion. At the early stage of the vegetative and the sexual expansion, most microfibrils were deposited transversely to the cell axis on the inner surface of the new wall. Then, bundles of microfibrils, running in various directions, overlaid the transverse microfibrils already deposited, at the late stage of the both types of expansion. The pattern of microfibril deposition changed from the transverse to the bundled pattern about 4 hr after the vegetative and about 2 hr after the sexual cell division, respectively. The change of pattern of microfibril deposition seemed to be highly correlated with cessation of cell expansion. 相似文献
66.
Short-term administration of the glucose analog 5-thio-
-glucose to primiparous lactating rats reduced mammary tissue lactose concentrations to half of control levels. Treatment with colchicine alone caused slight reductions in mammary tissue lactose content. These treatments did not alter the morphology or degree of development of rough endoplasmic reticulum or Golgi apparatus, but did cause alterations in secretory vesicles. In mammary tissue from untreated lactating animals, large, swollen secretory vesicles were abundant in apical regions of epithelial cells. After thioglucose administration secretory vesicles in the apical cytoplasm were smaller and were more densely packed with contents. While administration of colchicine alone caused accumulation of large numbers of nearly fully swollen vesicles, treatment with both colchicine and thioglucose induced accumulation of smaller, less fully developed secretory vesicles which contained morphologically recognizable casein micelles. Mammary tissue from late gestation rats was low in lactose; vesicles in this tissue resembled secretory vesicles in tissue from rats treated with thioglucose in that they were small and densely packed. These observations suggest that lactose, an osmoregulator in mammary gland, is transferred from Golgi apparatus to the apical cell surface within secretory vesicles. Lactose appears to be important for secretory vesicle maturation in mammary epithelial cells. 相似文献
67.
Yoshinori Asakawa Masao Toyota Masaharu Uemoto Takaaki Aratani 《Phytochemistry》1976,15(12):1929-1931
The distribution in six Porella species of drimane-, aromadendrane- and pinguisane-type sesquiterpenes and norsesquiterpenes is described. The sharp pungent substance of P. gracillissima, P. fauriei and P. macroloba is (+)-tadeonal. 相似文献
68.
The latent phenolase in spinach chloroplast membranes could be activated by treatment with various detergents. Examination by thin-layer gel filtration showed the presence of two active proteins (one with lower MW called protein A and the other, protein B). The protein B was converted to A by dilution or on standing, and the latter conversely to the former by concentration. On freezing, an extract of the acetone powder of the chloroplasts, phenolase activity was strikingly reduced, and this is ascribed to an association of the protein A and a low MW (diffusible) substance giving rise to an inactive enzyme-inhibitor complex. The activity declined from autumn to winter, and it appears that the second type of latency due to the formation of the above complex is also involved. 相似文献
69.
70.
Hiroshi Kihara Satoshi Saigo Hiroshi Nakatani Keitaro Hiromi Masao Ikeda-Saito Tetsutaro Iizuka 《BBA》1976,430(2):225-243
Kinetic studies of the isomerization reaction of horse heart ferricytochrome c between pH 8.5 and pH 12.1 have been carried out by using stopped-flow and rapid scanning stopped-flow techniques. Below pH 10, our results were in good agreement with the scheme proposed earlier (Davis, L. A., Schejter, A. and Hess, G. P. (1974) J. Biol. Chem. 249, 2624–2632). Above pH 10, another faster first-order process was observed, which suggested the existence of a transient species in the isomerization reaction between the species with and without a 695 nm band. The probable scheme of the isomerization reaction is considered to be where H denotes a proton, the colored forms are the species predominant at neutral pH with a 695 nm band and the noncolored forms are the species without a 695 nm band. The transient species has a small 695 nm absorbance which suggests that the sixth ligand is still Met-80, although the protein conformation might be different from that at neutral pH. 相似文献