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121.
Excretion of the penicillinase of an alkalophilic Bacillus sp. through the Escherichia coli outer membrane. 总被引:7,自引:3,他引:4
Two plasmids containing the penicillinase gene of alkalophilic Bacillus sp. strain 170, pEAP1 and pEAP2, were constructed. Most of the penicillinase produced by Escherichia coli, which carried these plasmids, was found in the culture medium. This excretion is caused by the cloned DNA fragment which contains some component that changes the outer membrane of E. coli. 相似文献
122.
Dipeptidyl aminopeptidase, which hydrolyzes the 7-(Gly-Pro)-4-methylcoumarinamide, has been purified from the brains of 3 week-old rats. It was purified about 2,600-fold by column chromatography on CM-cellulose, hydroxyapatite and Gly-Pro AH-Sepharose. This enzyme hydrolyzed Lys-Ala-beta-naphthylamide well with an optimum pH of 5.5. It was inhibited by diisopropyl fluorophosphate, phenyl-methanesulfonyl fluoride, some cations, and puromycin, but was not inhibited by p-chloromercuribenzoate, N-ethylmaleimide, dithiothreitol, EDTA, iodoacetic acid, and bacitracin, indicating that rat brain dipeptidyl aminopeptidase is a serine protease. This enzyme showed a molecular weight of 220,000 by gel filtration and of 51,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The properties of purified rat brain dipeptidyl aminopeptidase were similar to those of bovine pituitary dipeptidyl peptidase II, but the molecular weight and substrate specificity of these enzymes were different. 相似文献
123.
Enhancement of adipose S-100 protein release by catecholamines 总被引:2,自引:0,他引:2
When rat epididymal fat-pad pieces were incubated in vitro with 10 microM epinephrine, S-100 protein in the tissue was markedly decreased by release into the medium. The release of adipose S-100 protein was also enhanced by norepinephrine (10 microM), isoproterenol (10 microM), and dibutyryl cyclic AMP (5 mM), but not by insulin (0.8 microM). The enhancement of S-100 protein release by 10 microM epinephrine was completely inhibited by 10 microM propranolol. These results suggest that the release of adipose S-100 protein is regulated by the beta-adrenergic effect of catecholamines. 相似文献
124.
It was demonstrated that thyrotropin-releasing hormone (TRH) elicited a paradoxical increase in basal GH levels in cancer patients. Out of 94 cancer patients, 50 were found to be GH responders and this phenomenon was more frequently recognized in female than in male cancer patients. In cancer patients under 59 years of age, the GH response to TRH was significantly greater in females than in males, although there was no sex difference in the GH response in patients above 60 years of age. In female cancer patients, the GH response to TRH was significantly greater in patients under 59 years of age than in patients above 60 years of age, while there was no age difference in the GH response in male cancer patients. It was concluded that paradoxical responses of serum GH to TRH were recognized in 53 per cent of cancer patients and were more frequently observed in female than in male cancer patients. 相似文献
125.
M Kurono Y Hirachi Y Kato Y Toda N Takemasa S Kotani T Takahashi I Tadokoro 《Biken journal》1983,26(3):103-111
Intergenus cell fusion of prokaryotic bacteria was demonstrated for the first time; namely, fusion products doubly resistant to streptomycin and tetracycline were produced by polyethylene glycol treatment of a mixture of the streptomycin-resistant L-form of Pseudomonas aeruginosa and tetracycline-resistant L-form of Escherichia coli. 相似文献
126.
M Kinoshita Y Kato M Tsuji T Kono Y Hiraki F Suzuki 《Biochimica et biophysica acta》1983,757(3):324-331
The effect of prostaglandin analogues on the cyclic AMP level in cultured chondrocytes were examined. Prostaglandin E1 at 0.4 to 30 microM, increased the intracellular concentration of cyclic AMP in chondrocytes. Its effect was rapid, being evident within 1 min and reaching a maximum in 10 to 20 min. The maximum level was sustained until 30 min after its addition and then decreased gradually. Prostaglandin D2 and E2 also increased the cyclic AMP level in chondrocytes, but they had less effect than prostaglandin E1. Prostaglandin A1 had no effect on the nucleotide level in chondrocytes, although they markedly increased the level in fibroblasts. The time course of stimulation of cyclic AMP accumulation in chondrocytes by prostaglandin E1, D2 or E2 was quite different from that by parathyroid hormone (PTH): the effect of prostaglandin was slower and more sustained than that of PTH. PTH potentiated the effect of prostaglandin E1, E2, or D2 on the cyclic AMP level in chondrocytes and that the combined effects of prostaglandin and PTH were more than additive. Addition of an inhibitor of cyclic nucleotide phosphodiesterase with prostaglandin, PTH or both produced a synergistic effect on the accumulation of cyclic AMP in the chondrocytes. These findings suggest that prostaglandin E1, E2, and D2 increase the synthesis of cyclic AMP and that the combined effect of the prostaglandins and PTH on the cyclic AMP level in chondrocytes is partly attributed to the synergistic synthesis of cyclic AMP in the cells. 相似文献
127.
When investigating the effects of divalent cations (Mg2+, Ca2+, Sr2+, Ba2+, Mn2+ and Ni2+) on 3H-baclofen binding to rat cerebellar synaptic membranes, we found that the specific binding of 3H-baclofen was not only dependent on divalent cations, but was increased dose-dependently in the presence of these cations. The effects were in the following order of potency: Mn2+ congruent to Ni2+ greater than Mg2+ greater than Ca2+ greater than Sr2+ greater than Ba2+. Scatchard analysis of the binding data revealed a single component of the binding sites in the presence of 2.5 mM MgCl2, 2.5 mM CaCl2 or 0.3 mM MnCl2 whereas two components appeared in the presence of 2.5 mM MnCl2 or 1 mM NiCl2. In the former, divalent cations altered the apparent affinity (Kd) without affecting density of the binding sites (Bmax). In the latter, the high-affinity sites showed a higher affinity and lower density of the binding sites than did the single component of the former. As the maximal effects of four cations (Mg2+, Ca2+, Mn2+ and Ni2+) were not additive, there are probably common sites of action of these divalent cations. Among the ligands for GABAB sites, the affinity for (-), (+) and (+/-) baclofen, GABA and beta-phenyl GABA increased 2-6 fold in the presence of 2.5 mM MnCl2, in comparison with that in HEPES-buffered Krebs solution (containing 2.5 mM CaCl2 and 1.2 mM MgSO4), whereas that for muscimol was decreased to one-fifth. Thus, the affinity of GABAB sites for its ligands is probably regulated by divalent cations, through common sites of action. 相似文献
128.
Nobuyuki Sasakawa Konosuke Kumakura Satoshi Yamamoto Ryuichi Kato 《Life sciences》1983,33(20):2017-2024
Effects of N-(6-aminohexyl)-5-chloro-1-naph-thalenesulfonamide (W-7), a calmodulin antagonist, on catecholamine (CA) release and 45Ca2+ uptake were studied using cultured bovine adrenal chromaffin cells. W-7 inhibited the carbamylcholine (CCh)-evoked CA release and 45Ca2+ uptake in a concentration-dependent manner. The inhibitory effect of W-7 on CCh-evoked CA release was not overcome either by an increase in extracellular calcium or CCh concentration. Although W-7 inhibited the high K+-evoked CA release and 45Ca2+ uptake, potency of the drug was approximately 50–100 fold less than when inhibiting the CCh-evoked CA release and 45Ca2+ uptake. The inhibitory effects of W-7 were observed both in norepinephrine release and epinephrine release. Moreover, W-7 inhibited the CCh-evoked 45Ca2+ efflux. These results suggest that the inhibition of CA release by W-7 in adrenal chromaffin cells is mainly due to its inhibition of calcium uptake. W-7 may influence the linkage between acetylcholine-receptor and calcium uptake with higher potency than depolarization-dependent calcium entry. 相似文献
129.
Cadaverine, a 5-carbon diamine, was identified as the cofactorof uricase activity previously found in soybean seedlings. Thesubstance purified from freeze dried hypocotyls was subjectedto liquid chromatography, mass spectrometry, 1H- and 13C-nuclearmagnetic resonance spectrometry for identification. The concentrationsof cadaverine in 3-day-old radicles and hypocotyls were 2.37mM and 5.09 mM, respectively. Other polyamine concentrationswere low. Biogenic polyamines (cadaverine, putrescine, spermidineand spermine) functioned as cofactors, whereas conjugated polyamines(tyramine and histamine) and amino acids had no effect. Theaddition of catalase to the assay system counteracted the effectof cadaverine. Peroxide at appropriate concentrations actedlike cadaverine with an identical Km value, suggesting thaturate degrading activity can be ascribed to the diamine oxidase-peroxidasesystem. (Received October 19, 1982; Accepted December 23, 1982) 相似文献
130.
A total of 228 pesticides (88 insecticides, 60 fungicides, 62 herbicides, 12 plant-growth regulators, 3 metabolites and 3 other compounds) was tested for mutagenicity in bacterial reversion-assay systems with 5 strains (TA100, TA98, TA1535, TA1537 and TA1538) of Salmonella typhimurium and a strain (WP2 hcr) of Escherichia coli. 50 pesticides (25 insecticides, 20 fungicides, 3 herbicides, 1 plant-growth regulator and 1 other compound) were found to be mutagenic. 5 of them required metabolic activation (S9 mix) for their activities. Among various chemical groups, organic phosphates, halogenated alkanes and dithiocarbamates showed higher ratios of mutagens. Although 22 of the pesticides tested have been reported to be carcinogenic, 7 of them, i.e., captain, DBCP, EDB, EDC, ETU, HEH and nitrofen, were detected as mutagens in the present assay. Most of the other 15 non-mutagenic carcinogens were organochlorine pesticides such as alpha-BHC, chlorobenzilate, p,p'-DDT, dieldrin and quintozene. 相似文献