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81.
Complementarity of regulation for the two glutamine synthetases from Bacillus caldolyticus, an extreme thermophile 总被引:1,自引:0,他引:1
F C Wedler D S Shreve K E Fisher D J Merkler 《Archives of biochemistry and biophysics》1981,211(1):276-287
Chromatophores from Rhodopseudomonas capsulata cells grown semiaerobically in the dark oxidize NADH, succinate, and dichlorophenolindophenol. In the presence of N3? these activities are inhibited, but light induces oxidation of dichlorophenolindophenol with O2 as a terminal electron acceptor. Cyanide also inhibits electron transport but much higher concentrations are required to inhibit the photooxidation than the dark oxidation. The photooxidation was studied in a mutant strain of Rhodopseudomonas capsulata (YIV) which cannot grow anaerobically in the light, but similarly to the wild type, grows in the presence of oxygen. Chromatophores from YIV mutant catalyze photophosphorylation and dark oxidation activities with the same properties as those of the wild type. However, the rate of photooxidation in the mutant is only one-third that of the wild type. Based on the differential inhibitor sensitivity and on the mutation it is suggested that the photooxidase is different from the two respiratory oxidases and that this photooxidation activity might be essential for growth of the cells under anaerobic conditions in the light. 相似文献
82.
V. Luu-The J. Cumps P. Dumont 《Biochemical and biophysical research communications》1980,93(3):776-781
Using homogeneous cytochrome P-450, we have shown that the well-known metyrapone-dithionite reduced cytochrome P-450 complex is specific for the cytochrome P-450b induced by phenobarbital. A linear relationship was observed between the absorbance of metyrapone-reduced cytochrome P-450 complex and the one of CO-reduced cytochrome P-450 complex, the usual method for the determination of cytochrome P-450. A method has been proposed for the specific determination of the cytochrome P-450b. 相似文献
83.
The time and dose dependence of the relationship between uptake of labelled precursors into protein and RNA and production of testosterone by rabbit follicles was examined. Although testosterone production was stimulated by luteinizing hormone at concentrations between 0.1 and 10 microgram/ml, the uptake of [3H]leucine into protein was significant only when the concentration of luteinizing hormone was greater than 2.5 microgram/ml. Increased production of testosterone was observed within 15 min of stimulation with luteinizing hormone whereas uptake of [3H]leucine was only significant at 90 min. Puromycin (40 microgram/ml) and cycloheximide (10 microgram/ml) in the presence of luteinizing hormone inhibited the synthesis of both testosterone and protein. However, lower concentrations of puromycin (0.1, 1 and 10 microgram/ml) and cycloheximide (1 microgram/ml) had no effect on luteinizing hormone-induced testosterone production but significantly inhibited protein synthesis by 58, 37, 31 and 71%, respectively. Actinomycin D (20, 80 and 160 microgram/ml) alone and in combination with 5 microgram luteinizing hormone/ml severely inhibited uptake of [3H]uridine into RNA without affecting testosterone production. However, with 1 microgram actinomycin/ml, testosterone production was significantly (P less than 0.01) greater than in the presence of luteinizing hormone alone. These results cast doubt on the obligatory role of RNA and protein synthesis in rabbit ovarian follicular steroidogenesis. 相似文献
84.
This study evaluates dopaminergic regulation of aldosterone secretion in 6 patients with high spinal cord transections. Administration of the dopamine antagonist metoclopramide resulted in a marked rise in plasma aldosterone and 18-hydroxycorticosterone levels in 12 normal individuals, but no change in plasma levels of these zona glomerulosa corticosteroid products in spinal cord patients. Spinal cord transected patients also did not have the rise in plasma renin activity that was observed in normals following metoclopramide administration. Basal levels of aldosterone, 18 hydroxycorticosterone, corticosterone and renin activity as well as the aldosterone responses to graded dose infusion of adrenocorticotropin were similar in the spinal cord patients and the normals. These data suggest that dopaminergic regulation of adrenal zona glomerulosa corticosteroid and renal renin secretion is absent in patients with high spinal cord transections, suggesting that intact neural pathways from the central nervous system are necessary for metoclopramide stimulation of aldosterone and renin secretion in men. Since basal plasma aldosterone levels were normal in spinal cord transected patients, it appears that the absence of dopaminergic control does not result in elevated secretion. 相似文献
85.
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87.
Structural membrane lipids are known to contribute to the high ethanol resistance of Saccharomyces cerevisiae (2, 4, 17). By manipulating the yeast cellular sterol level by changing the carbon-to-nitrogen source ratio in the chemostat growth medium, high delta 5,7-sterol levels were found to increase the resistance of yeast populations to ethanol-induced death. The resistance of the erg2 (delta 8----delta 7-sterol isomerase) mutant to ethanol-induced death was generally comparable with that of the delta 5,7-sterol-synthesizing strain. In contrast, the sensitivity of anaerobic growth to inhibition by ethanol was higher in the erg2 mutant in comparison with the delta 5,7-sterol-synthesizing strains but a high level of those sterols increased the vulnerability of anaerobic growth to ethanol inhibition. 相似文献
88.
M V Sauer 《The Western journal of medicine》1994,161(2):164-165
89.
Forty-two white-rot fungi isolated in South America were incubated with long fibre sugar cane bagasse (LFB). The residual composition of LFB was determined after white-rot decay at 30 and 60 days. The ratio of residual lignin to residual lignin to residual cellulose (RL/RC) of untreated material (LFB) was 0.48. After white-rot-decay, the residual material with lower RL/RC ratios indicated that mainly lignin was degraded. In only 30 days, Phlebia sp. MVHC 5535, Athelia sp. MVHC 5509 and Spongipellis pachyodon MVHC 5019 caused a decrease in the RL/RC ratio to 0.36, 0.37 and 0.38, respectively, while it took 60 days for Ganoderma applanatum MVHC 5347, Hyphodontia sp. MVHC 5544, Panus tigrinus MVHC 5400, Stereum sp. MVHC 5113, Phellinus punctatus MVHC 5346 and MVHC 6388 to reach a ratio lower than 0.40. No correlation was found between the amount of some ligninolytic enzymes secreted and the residual composition of bagasse after white-rot fungi fermentation. Most of the fungal strains caused an increase in the relative amount of residual cellulose, indicating that hemicellulose was the preferred energy source. 相似文献
90.