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1.
Michinari Hamaguchi Koichiro Maeno Yoshiyuki Nagai Masao Iinuma Tetsuya Yoshida Toshisada Matsumoto 《Microbiology and immunology》1980,24(1):51-63
When p-fluorophenylalanine (FPA) was added to influenza virus RI/5+-infected cells 4 hr after infection, virus-specific proteins were synthesized but infectious progeny virus was not produced. In these cells, synthesis of viral RNA was strongly inhibited and nucleoprotein (NP) antigen was found predominantly in the nucleus in contrast to untreated cells in which NP antigen was distributed throughout the whole cell. The intracellular location and migration of NP were examined by isotope labeling followed by fractionation of infected cells. In untreated cells, a large portion of the NP was present in the cytoplasm and most of it was detected in the form of ribonucleoprotein (RNP). In contrast, in FPA-treated cells little viral RNP was detectable and NP was present predominantly in the nucleus in a nonassembled, soluble form. When FPA was removed from the culture, synthesis of viral RNA was soon restored and a large amount of viral RNP appeared in the cytoplasm; this was followed by the production of infectious virus. The results of the experiments suggest that the NP synthesized in the presence of FPA is not assembled into viral RNP because of the lack of available RNA, and such NP migrates readily into the nucleus and accumulates there. 相似文献
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Expression, purification, and crystallization of endopolygalacturonase from a pathogenic fungus, Stereum purpureum, in Escherichia coli 总被引:1,自引:0,他引:1
Shimizu T Shibata H Araya T Nakatsu T Miyairi K Okuno T Kato H 《Protein expression and purification》2005,44(2):558-135
Endopolygalacturonases (EC 3.2.1.15) catalyze random hydrolysis of the alpha-1,4 glycosidic linkages in polygalacturonic acid, a component of pectin. Previously, we reported crystal structures of endogenously produced Stereum purprureum endopolygalacturonase I (endoPG I), both in its native form and complexed with its product, galacturonate. However, the substrate-binding mechanism of endoPG I is still unclear, because crystals have not yet been obtained with a substrate analog, or with mutant enzymes that can bind substrates. We describe here an expression system using Escherichia coli and a purification method to prepare functionally active endoPG I for such mutation and crystallographic studies. Expression in E. coli strain Origami (DE3) provided a soluble and active enzyme with proper disulfide bond formation, whereas the enzyme expressed in BL21 (DE3) was localized in inclusion bodies. A sufficient amount of recombinant endoPG I produced by Origami (DE3) was purified by a single-step procedure using cation exchange chromatography. The specific activity of recombinant endoPG I was equivalent to that of the enzyme produced by S. purpureum. Recombinant endoPG I was crystallized under the same conditions as those used for the native enzyme produced by S. purpureum. The crystals diffracted beyond 1.0 A resolution with synchrotron radiation. 相似文献
7.
Isao Takata Kozo Yamamoto Tetsuya Tosa Ichiro Chibata 《Applied microbiology and biotechnology》1979,7(2):161-172
Summary To develop an efficient method for continuous production of L-malic acid from fumaric acid using immobilized microbial cells, screening of microorganisms having high fumarase activity was carried out and cultural conditions of selected microorganisms were investigated. As a result of screening microorganisms belonging to the genera Brevibacterium, Proteus, Pseudomonas, and Sarcina were found to produce fumarase in high levels. Among these microorganisms Brevibacterium ammoniagenes, B. flavum, Proteus vulgaris, and Pseudomonas fluorescens were further selected for their high fumarase levels in the cultivation on several media. These 4 microorganisms were entrapped into a k-carrageenan gel lattice, and the resultant immobilized B. flavum showed the highest fumarase activity and operational stability.Cultural conditions for the fumarase formation and the operational stability of fumarase activity of immobilized B. flavum are detailed. Productivity for L-malic acid using immobilized B. flavum with k-carrageenan was 2.3 fold of that using immobilized B. ammoniagenes with polyacrylamide.Presented at the Annual Meeting of the Agricultural Chemical Society of Japan, Nagoya, April 3, 1978 相似文献
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Shigehara T Mitsuhashi H Ota F Kuroiwa T Kaneko Y Ueki K Tsukada Y Maezawa A Nojima Y 《Life sciences》2002,70(19):2225-2232
Sulfite is a major air pollutant which can cause respiratory tract inflammation characterized by an influx of polymorphonuclear neutrophils (PMN). We have previously shown that human PMN can produce sulfite either spontaneously or in response to stimulation with lipopolysaccharide. We now demonstrate that sulfite activates PMN to adhere to immobilized fibrinogen via the beta2-integrin Mac-1 (CD11b/CD18). Mac-1 expression is not altered by treatment with this agent. Although unaffected by pertussis toxin, sulfite-triggered PMN adhesion was abrogated by pretreating cells with the membrane-impermeant sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), a modifier of thiol groups on the cell surface. These results suggest that sulfite-induced PMN adhesion is dependent on a modification of thiols at the cell surface. Given its potent antioxidant and antimicrobial activities, sulfite may act as an endogenous mediator in host defense and/or inflammation. 相似文献
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We studied the relationship between the coexistence of tree species and the dynamics of organic matter in forests. A tropical peat swamp forest was selected as a model ecosystem, where abiotic factors, such as geological topography or parent rock types, are homogeneous and only biological processes create habitat heterogeneity. The temporal or spatial variation of the ground elevation of peat soils is mainly caused by changes in the balance between organic matter inputs to soils and decomposition, which is affected by the growth and death of influential trees. To clarify the processes of elevation dynamics, we measured the microtopography around some tree groups, estimated organic matter (in the form of litter and roots) in soils under three kinds of microtopographic conditions, measured decomposition rates and detected dominant species' shifting distribution patterns in different stages of growth in relation to the locations of tree groups creating specific microtopographic conditions. We found that growth or death of buttressed trees has the greatest effects on the rising or sinking of ground surfaces through changes in litter supply and root production. We discuss here the possibility of extending our model to other forest types. 相似文献
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Toba T Murata K Futamura J Nakanishi K Takahashi B Takemoto N Tomino M Nakatsuka T Imajo S Goto M Yamamura T Miyake S Annoura H 《Bioorganic & medicinal chemistry》2012,20(9):2850-2859
A series of truncated analogs of α-galactosylceramide with altered ceramide moiety was prepared, and evaluated for Th2-biased response in the context of IL-4/IFN-γ ratio. Phytosphingosine-modified analogs including cyclic, aromatic and ethereal compounds as well as the C-glycoside analog of OCH (2) with their cytokine inducing profile are disclosed. 相似文献