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Oxidation of liposome phospholipids has been studied in the presence of cytochrome c. Sonicated vesicles of soya bean or egg-yolk lipids, or purified phospholipid preparations, were treated with oxidized cytochrome c at a 10:4 lipid/protein ratio (w/w). Lipid peroxidation was examined by oxygen polarography, gas-liquid chromatography (GLC) and the thiobarbituric acid test. Oxidized, but not reduced, cytochrome effectively catalyzes lipid oxidation under these conditions. Oxygen consumption and disappearance of unsaturated fatty acids follow closely similar patterns, the O2 consumption rate showing a maximum (1.53 mol O2/min per mol heme) shortly before fatty acid loss reaches its peak. GLC and O2 consumption data suggest that monohydroperoxides are the most abundant oxidized species in the system. The thiobarbituric acid reaction, however, appears only to be of qualitative value in peroxidation studies. In order to test the mechanism through which oxidation occurs in our system, the effect of liposome composition and the presence of antioxidants was tested, both on cytochrome c binding to bilayers and on O2 consumption. Oxidized and reduced cytochrome c bind the lipid bilayers with similar affinity, but only the oxidized form is active in autoxidation. Antioxidants do not modify either cytochrome c binding to sonicated liposomes. Lipid composition does influence considerably cytochrome binding, and O2 consumption is correspondingly altered. Studies with various antioxidants and inhibitors suggest that both free radicals and singlet oxygen may be involved in the process under study. 相似文献
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Bovine-heart mitochondrial complex III was purified in the presence of Triton X-100, and the size and shape of the resulting protein-surfactant-phospholipid mixed micelles were investigated by laser light-scattering. The protein appears to be present in the form of a dimer, irrespective of temperature (between 25 and 40 degrees C) and protein concentration (between 0.5 and 5 mg/ml). The molecular weight of the micelle increases with temperature from 600 000 (25 degrees C) to 692 000 (40 degrees C). The variation of the solvent second virial coefficient in this temperature range suggests that, with increasing temperature, some of the free surfactant molecules become integrated in the mixed micelles. The average quadratic radius of gyration of these is of 42 +/- 5 nm, corresponding in our case to an ellipsoidal shape. 相似文献
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Distribution, quantitation, and origin of immunoreactive neuropeptide Y in the human gastrointestinal tract 总被引:1,自引:0,他引:1
A radioimmunoassay for measurement of immunoreactive neuropeptide Y has been developed using antiserum from a rabbit (221) immunized with porcine neuropeptide Y. Antibody 221 has been characterized for both sensitivity and specificity. To determine the distribution of neuropeptide Y in the human gastrointestinal tract, fresh tissue specimens were separated by microdissection into the muscularis externa and the mucosa-submucosa. To examine the origin of neuropeptide Y in human colon, specimens of aganglionic and ganglionic colon were obtained from patients with Hirschsprung's disease. Immunoreactive neuropeptide Y in human gut was present in highest concentrations in the muscularis externa of the stomach and in lowest concentrations in the muscularis externa of the ileum and descending colon. Neuropeptide Y in the stomach was present in higher concentrations in the muscularis externa than in the mucosa-submucosa, but in the descending colon there were lower concentrations of neuropeptide Y in the muscularis externa than in the mucosa-submucosa. In Hirschsprung's disease, concentrations of neuropeptide Y were increased in aganglionic colon in both the muscularis externa and the mucosa-submucosa, compared to corresponding layers from proximal ganglionic colon. Extracts of the gastric muscularis externa and the colonic mucosa-submucosa were separated by C18 reverse-phase high-performance liquid chromatography. One major immunoreactive species was identified by radioimmunoassay which eluted in a position similar to synthetic human neuropeptide Y. These results demonstrated both regional and layer differences in concentrations of neuropeptide Y in human gut. Increased concentrations of neuropeptide Y in aganglionic colon from Hirschsprung's disease most likely result from enlargement of neuropeptide Y-containing extrinsic nerve fibers in both the mucosa-submucosa and the muscularis externa. 相似文献
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Summary Using the monotone dependence function (mdf) together with correlation coefficient it was found that the Ma-DNA content as well as total protein content are regularly, linearly, positively and strongly dependent in sister cells (proter-opisthe) ofChilodonella steini. Additionally it was shown that proter-opisthe ordering is irrelevant to Ma-DNA and protein contents.Analysis of sister cell generation times (TG) confirmed the existence of regular, linear, positive and strong codependence.The relations between Ma-DNA and total protein contents, between protein content and TG, and between Ma-DNA content and TG were also described. There is a weak, linear dependence between Ma-DNA and total protein contents. Relations of TG and Ma-DNA content or TG and total protein content are non-linear and not even monotone. Low and high levels of DNA or proteins are connected with long generation times. 相似文献
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Kaoru Hatanaka Masami Imakita Soei Go Akira Yamamoto M.D. 《Cell and tissue research》1986,246(1):53-56
Summary A mast-cell activator, compound 48/80, causes proliferation of mesenchymal cells in the mesentery of rats. Its effect on W/W
vmice deficient in mast cells was tested to determine whether the proliferation is mediated in the degranulation of mast cells. Incorporation of [3H]thymidine into mesenchymal cells in the mesentery of these mice with or without compound 48/80 was very small compared to their normal litter mates. However, bone marrow transplantation markedly enhanced the effect of compound 48/80, and resulted in an incorporation of [3H]thymidine almost comparable to that observed in normal mice. Our results provide evidence that mesenchymal cell proliferation is caused by a product secreted by mast cells when stimulated by compound 48/80.Supported by a Grant-in-Aid for Scientific Research, No. 366, from the Japanese Ministry of Health and WelfareThe authors are indebted to Drs. Motomu Minamiyama and Yukio Hirata for valuable advices, and to Miss Mitsuko Inoue for technical assistance 相似文献
9.
A.S.C. Wan T.L. Ngiam S.L. Leung M.L. Go P.W.S. Heng P.N. Natarajan A. Shafiee M. Vossoghi F. Savabi C.G. Francisco R. Freire R. Hernandez J.A. Salazar E. Suarez G.A.Garcia De La Mora Y.Grillasca R. O. Jimeno 《Steroids》1983,41(3):309-320
The synthesis of esters of norethisterone (17α-ethynyl-17β-hydroxy-estr-4-en-3-one) with acids containing a benzene ring is described, two methods of esterification being compared in terms of yield and convenience. The activities of these esters as long-acting contraceptive agents have been evaluated. 相似文献
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