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排序方式: 共有619条查询结果,搜索用时 15 毫秒
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Karlheinz Grillitsch Pablo Tarazona Lisa Klug Tamara Wriessnegger Günther Zellnig Erich Leitner Ivo Feussner Günther Daum 《生物化学与生物物理学报:生物膜》2014
Despite similarities of cellular membranes in all eukaryotes, every compartment displays characteristic and often unique features which are important for the functions of the specific organelles. In the present study, we biochemically characterized the plasma membrane of the methylotrophic yeast Pichia pastoris with emphasis on the lipids which form the matrix of this compartment. Prerequisite for this effort was the design of a standardized and reliable isolation protocol of the plasma membrane at high purity. Analysis of isolated plasma membrane samples from P. pastoris revealed an increase of phosphatidylserine and a decrease of phosphatidylcholine compared to bulk membranes. The amount of saturated fatty acids in the plasma membrane was higher than in total cell extracts. Ergosterol, the final product of the yeast sterol biosynthetic pathway, was found to be enriched in plasma membrane fractions, although markedly lower than in Saccharomyces cerevisiae. A further characteristic feature of the plasma membrane from P. pastoris was the enrichment of inositol phosphorylceramides over neutral sphingolipids, which accumulated in internal membranes. The detailed analysis of the P. pastoris plasma membrane is discussed in the light of cell biological features of this microorganism especially as a microbial cell factory for heterologous protein production. 相似文献
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Effect of Photon Fluence Rate on Oxygen Evolution and Uptake by Chlamydomonas reinhardtii Suspensions Grown in Ambient and CO(2)-Enriched Air 总被引:4,自引:4,他引:0
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A closed system consisting of an assimilation chamber furnished with a membrane inlet from the liquid phase connected to a mass spectrometer was used to measure O2 evolution and uptake by Chlamydomonas reinhardtii cells grown in ambient (0.034% CO2) or CO2-enriched (5% CO2) air. At pH = 6.9, 28°C and concentrations of dissolved inorganic carbon (DIC) saturating for photosynthesis, O2 uptake in the light (Uo) equaled O2 production (Eo) at the light compensation point (15 micromoles photons per square meter per second). Eo and Uo increased with increasing photon fluence rate (PFR) but were not rate saturated at 600 micromoles photons per square meter per second, while net O2 exchange reached a saturation level near 500 micromoles photons per square meter per second which was nearly the same for both, CO2-grown and air-grown cells. Comparison of the Uo/Eo ratios between air-grown and CO2-grown C. reinhardtii showed higher values for air-grown cells at light intensities higher than light compensation. For both, air-grown and CO2-grown algae the rates of mitochondrial O2 uptake in the dark measured immediately before and 5 minutes after illumination were much lower than Uo at PFR saturating for net photosynthesis. We conclude that noncyclic electron flow from water to NADP+ and pseudocyclic electron flow via photosystem I to O2 both significantly contribute to O2 exchange in the light. In contrast, mitochondrial respiration and photosynthetic carbon oxidation cycle are regarded as minor O2 consuming reactions in the light in both, air-grown and CO2-grown cells. It is suggested that the “extra” O2 uptake by air-grown algae provides ATP required for the energy dependent CO2/HCO3− concentrating mechanism known to be present in these cells. 相似文献
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The fatty acid composition of the fruit oils or seed oils of Pittosporaceae (eight genera, 10 species), Araliaceae (two species), Simarubaceae (three species), and of one umbelliferous and one rutaceous species were determined by gas chromatography, argentation TLC and ozonolysis. In the Pittosporaceae, in which the major C18 fatty acid of all species was either oleic acid (18:1, 9c) or linoleic acid (18:2, 9c, 12c), large amounts of C20 and C22 fatty acids seem to occur regularly. Petroselinic (18:1, 6c) and tariric (18:1, 6a) acids were absent. However, petroselinic acid was the major fatty acid in the Araliaceae and Umbelliferae. In these two families only small amounts of C20 and C22 acids were detected and tariric acid was absent. The Rutales contained relatively high amounts of trans-octadecenoic acids (18:1, 9t). Tariric acid was the major fatty acid in the two species of Picramnia (Simarubraceae), which also contained small amounts of petroselinic acid. The major fatty acids in Ailanthus glandulosa (Simarubaceae) and Phellodendron amurense (Rutaceae) were linoleic or linolenic acid (18:3, 9c, 12c, 15c); these species contained neither tariric nor petroselinic acid and the levels of C20 and C22 fatty acids were low. The appearance of schizogenous resin canals and polyacetylenes and the absence of iridoids and petroselinic acid allows the Pittosporaceae to be separated from the Rutales and Araliales and to be placed in an independent order, the Pittosporales. Arguments for a rather close relationship of the Pittosporales to the Araliales and Cornales (including the Escalloniaceae) are presented. 相似文献
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A model for the tertiary structure of mammalian mitochondrial transfer RNAs lacking the entire 'dihydrouridine' loop and stem 总被引:18,自引:1,他引:17
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The mammalian mitochondrial tRNA(AGY)Ser is unique in lacking the entire dihydrouridine arm. This reduces its secondary structure to a 'truncated cloverleaf'. Experimental evidence on the tertiary structure has been obtained by chemically probing the conformation of both the bovine and human species in their native conformation and at various stages of denaturation. A structural model of the bovine tRNA is presented based on the results of this chemical probing, on a comparison between nine homologous 'truncated cloverleaf' secondary structures and on analogies with the crystal structure of yeast phenylalanine tRNA. The proposed structure is very similar in shape to that of yeast tRNA(Phe) but is slightly smaller in size. It is defined by a unique set of tertiary interactions. Structural considerations suggest that other mammalian mitochondrial tRNAs have smaller dimensions as well. 相似文献
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Degradation of Hydrocarbons by Members of the Genus Candida: I. Hydrocarbon Assimilation 总被引:2,自引:2,他引:0
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A representative number of species of the genus Candida were tested for their ability to utilize n-alkanes of 9 to 18 carbon atoms and even-numbered 1-alkenes of 10 to 18 carbon atoms. A high percentage of these organisms exhibited the ability to assimilate some member of the hydrocarbon series employed. These findings indicate that the ability to assimilate hydrocarbons is not limited to a few species of the genus and may be of some taxonomic significance. 相似文献
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