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91.
Roland Salesse Yves Combarnous Sabine Brahms Jean Garnier 《Archives of biochemistry and biophysics》1981,209(2):480-485
Porcine lutropin shares with ovine lutropin common structural features. They exhibit identical vacuum circular dichroism down to 170 nm with characteristic negative bands at 173, 194, and 210 nm. The band at 210 ± 1 nm is shifted to 201 nm upon dissociation with disappearance of the 194-nm band. For the two hormones the acid transition involves a significant loss of the three recognized periodic structures α helix, β sheet, and β turns of type II, unshields near the same number of tyrosyl residues (2.2 ± 0.7), and gives rise to an identical absorption difference at 287 nm in a two-step mechanism. However, pLH also exhibits noticeable differences: 5 to 10 times lower rates of acid transition with a lower pKa (3.7 ± 0.1) and different transition behavior of tyrosine residues compared to ovine lutropin. 相似文献
92.
Roland Kühne 《Journal of insect physiology》1982,28(2):155-163
The response characteristics of the vibration receptors in the legs of the migratory locust, Locusta migratoria, and the tettigoniid Decticus verrucivorus were investigated electro-physiologically by single cell recordings. The legs were stimulated by sinusoidal vibrations. There are four types of vibration receptor in each leg of Locusta and Decticus, which can be classified physiologically. One type—most probably campaniform sensilla—shows a phase-locked response to vibrations from 30 to 200 Hz, its threshold reflecting the displacement. A second type shows similar responses in the same frequency range, but its reactions depend on the stimulus acceleration. The receptor cells of the subgenual organ are very sensitive to vibration from 30 to at least 5000 Hz, and their responses depend on acceleration. There are two types of subgenual receptors, one of which shows a clear maximum of sensitivity between 200 and 1000 Hz, with a threshold below 0.01 m/sec?2 acceleration. Subgenual receptors with different thresholds and different characteristic frequencies occur in each leg. The receptors of each leg pair have quite similar mean sensitivities and characteristic frequencies. However, in the front legs of tettigoniids the more sensitive subgenual receptors and an additional receptor type also respond to low-frequency airborne sound up to 10 kHz. 相似文献
93.
Robert O. Hussa Roland A. Pattillo 《In vitro cellular & developmental biology. Plant》1980,16(7):585-590
Summary The BeWo line of trophoblastic cells, maintained in continuous culture since 1966, was employed to investigate the phenomenon
of gonadotropin α-subunit predominance that exists in several cell lines. The secretion of complete human chorionic gonadotropin
(hCG) relative to α-subunit was compared in several different BeWo sublines, all of which were derived from BeWo stock roller
tube colonies. In all of the BeWo sublines, secretion of hCG originally exceeded secretion of α-subunit. With time in culture,
however, there was a marked decline in production of hCG/hCGβ, but not in α-subunit. Thus it appears that the production of
hCGβ by BeWo choriocarcinoma cells is more labile than the production of the α-subunit. 相似文献
94.
Beate Ackermann-Schmidt Roland Süssmuth Franz Lingens 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,699(2)
The mutagen 1,1′-hexamethylene-bis[(5-p-chlorophenyl)-biguanide] reacts at 37°C with guanosine and guanine to yield xanthosine or xanthine and oxidizes cysteine to cystine. After treatment of a guanosine-labelled DNA sample from Escherichia coli with the mutagen xanthine could be detected as a reaction product. At a slow rate the mutagen is hydrolysed spontaneously yielding urea, 1,6-hexanediol and 4-chloroaniline. The reaction mechanisms both of the hydrolysis and of the reaction with cysteine and guanosine are discussed. 相似文献
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98.
The reversibility of the binding of ionophores to the thylakoid membrane is studied. While gramicidin binds practically irreversibly, valinomycin and nonactin bind reversibly, however, only a small fraction (about 1 %) of the membrane-bound valinomycin or nonactin is active in ion transport. The current-voltage relationship is evaluated under these circumstances. We have found that it is practically linear. This together with the relationship between current and ion concentration agrees qualitatively with the results reported for bimolecular lipid membranes, which contain a large fraction of negatively charged lipids. For the ionophores, valinomycin and nonactin, the binding equilibria (K ≈ 104) and the turnover numbers (≈ 3 · 104/s) are evaluated for their action on the thylakoid membrane. Possible reasons for the inactivity of the majority of membrane-bound ionophore molecules are discussed. 相似文献
99.
Robert Belmaker Helmut Beckmann Frederick Goodwin Dennis Murphy William Pollin Monte Buchsbaum Richard Wyatt Roland Ciaranello Friedhelm Lamprecht 《Life sciences》1975,16(2):273-279
The activity of dopamine-B-hydroxylase in blood has recently been demonstrated to be under genetic control and to correlate closely with urinary catecholamine excretion. The results of the present study did not demonstrate any relationship between a major catecholamine metabolite in urine, 3-methoxy-4-hydroxy phenylglycol, and dopamine-B-hydroxylase activity in plasma, monoamine oxidase activity in platelets, or monoamine oxidase activity in plasma. Differences in the origin of urinary catecholamines and urinary 3-methoxy-4-hydroxy phenyglycol may be responsible for these divergent results. 相似文献
100.
Changes in lectin-induced deoxyribonucleic acid synthesis in cultures of chick-embryo fibroblasts at various stages of development 下载免费PDF全文
Concanavalin A and Robinia pseudoacacia lectin decreased [(3)H]thymidine incorporation into acid-insoluble material of fibroblasts cultured from 6-10-day chick embryos. In contrast, these lectins stimulated [(3)H]thymidine incorporation in cells from 16-day embryos. These effects are due to neither [(3)H]thymidine permeability modification nor toxicity of the lectins. The specificity of lectin action was proved by blocking experiments with alpha-methyl mannopyranoside and with anti-(Robinia lectin) serum. 相似文献