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81.
T Sato N Tanaka S Neya N Funasaki T Iizuka Y Shiro 《Biochimica et biophysica acta》1992,1121(1-2):1-7
Examination was made of CO binding reactions to four kinds of modified sperm whale myoglobin (Mb), whose heme was reconstituted by iron complexes of synthetic porphyrins such as porphine (Por), meso-tetramethylporphyrin (TMeP), meso-tetraethylporphyrin (TEtP) and meso-tetra(n-propyl)porphyrin (TnPrP), using flash photolysis and stopped-flow methods. The CO association rate was found to be 5- to 20-times and dissociation rate 10- to 36-times accelerated by replacement with synthetic hemes. These features could be explained based on characteristic structures of modified Mbs indicated by X-ray crystallography. The side chain of Arg-45 protruded from the heme vicinity into the solvent region and heme was tilted by interactions of meso-alkyl side chains with surrounding peptides, resulting in the formation of widely opened channels and pockets for ligand passage. These structural features indicate the CO ligand to more easily enter or exit from heme pockets of reconstituted myoglobins, compared to native Mb. 相似文献
82.
Application of the micropipette technique to the measurement of cultured porcine aortic endothelial cell viscoelastic properties 总被引:13,自引:0,他引:13
M Sato D P Theret L T Wheeler N Ohshima R M Nerem 《Journal of biomechanical engineering》1990,112(3):263-268
The viscoelastic deformation of porcine aortic endothelial cells grown under static culture conditions was measured using the micropipette technique. Experiments were conducted both for control cells (mechanically or trypsin detached from the substrate) and for cells in which cytoskeletal elements were disrupted by cytochalasin B or colchicine. The time course of the aspirated length into the pipette was measured after applying a stepwise increase in aspiration pressure. To analyze the data, a standard linear viscoelastic half-space model of the endothelial cell was used. The aspirated length was expressed as an exponential function of time. The actin microfilaments were found to be the major cytoskeletal component determining the viscoelastic response of endothelial cells grown in static culture. 相似文献
83.
Comparison of OspA Serotypes for Borrelia burgdorferi Sensu Lato from Japan,Europe and North America
Toshiyuki Masuzawa Bettina Wilske Tetsuro Komikado Hiroyuki Suzuki Hiroki Kawabata Nanao Sato Koichi Muramatsu Nobutake Sato Emiko Isogai Hiroshi Isogai Russell C. Johnson Yasutake Yanagihara 《Microbiology and immunology》1996,40(8):539-545
Sixty-one Borrelia burgdorferi sensu lato strains from various sources (ticks, human, and wild animals) in Japan and two strains from ticks in Far Eastern Russia were classified on the basis of reactivity with 16 monoclonal antibodies (mAb) to outer surface protein A (OspA) and by DNA-DNA hybridization assay. Eleven OspA serotypes (J1 to J11) were recognized among the Japanese and the Far East Russian isolates (serotypes J1 to J9 were identified as B. garinii, serotype J10 was identified as B. afzelii, and serotype J11 corresponded to B. japonica), whereas 7 OspA serotypes for North American and European isolates previously reported (Bettina Wilske et al, J. Clin. Microbiol. 31:340-350, 1993) were not observed except for OspA serotype 2 which showed identical reactivity with OspA serotype J10. This finding provides helpful information for understanding the geographical distribution of Lyme disease borrelia and the development of vaccine and diagnostic tests. In conclusion: 1. B. burgdorferi sensu stricto has not been observed in Japan, 2. Japanese B. afzelii isolates are closely related to those from Europe, 3. B. garinii isolates from Japan are highly heterogeneous and apparently different from European B. garinii isolates. 相似文献
84.
JAK2 associates with the beta c chain of the receptor for granulocyte-macrophage colony-stimulating factor, and its activation requires the membrane-proximal region. 总被引:32,自引:10,他引:22 下载免费PDF全文
F W Quelle N Sato B A Witthuhn R C Inhorn M Eder A Miyajima J D Griffin J N Ihle 《Molecular and cellular biology》1994,14(7):4335-4341
The high-affinity receptor for granulocyte-macrophage colony-stimulating factor (GM-CSF) consists of a unique alpha chain and a beta c subunit that is shared with the receptors for interleukin-3 (IL-3) and IL-5. Two regions of the beta c chain have been defined; these include a membrane-proximal region of the cytoplasmic domain that is required for mitogenesis and a membrane-distal region that is required for activation of Ras, Raf-1, mitogen-activated protein kinase, and S6 kinase. Recent studies have implicated the cytoplasmic protein tyrosine kinase JAK2 in signalling through a number of the cytokine receptors, including the IL-3 and erythropoietin receptors. In the studies described here, we demonstrate that GM-CSF stimulation of cells induces the tyrosine phosphorylation of JAK2 and activates its in vitro kinase activity. Mutational analysis of the beta c chain demonstrates that only the membrane-proximal 62 amino acids of the cytosolic domain are required for JAK2 activation. Thus, JAK2 activation is correlated with induction of mitogenesis but does not, alone, activate the Ras pathway. Carboxyl truncations of the alpha chain, which inactivate the receptor for mitogenesis, are unable to mediate GM-CSF-induced JAK2 activation. Using baculovirus-expressed proteins, we further demonstrate that JAK2 physically associates with the beta c chain but not with the alpha chain. Together, the results further support the hypothesis that the JAK family of kinase are critical to coupling cytokine binding to tyrosine phosphorylation and ultimately mitogenesis. 相似文献
85.
86.
Distribution of Vacuolar H+-Pyrophosphatase and a Membrane Integral Protein in a Variety of Green Plants 总被引:2,自引:0,他引:2
Vacuolar membranes isolated from several species including fernand moss exhibited pyro-phosphate-dependent H+ transport activity.On immunoblot analysis, H+ -pyrophosphatase was detected inthe vacuolar membranes. A membrane integral protein of 23,000daltons was not found in the membranes of Chara, Conocephalum,or Kalanchoë. Thus, H+-pyrophosphatase may be a universalenzyme among green plants, but the 23-kDa protein is not a commonprotein of central vacuoles. (Received September 10, 1993; Accepted November 29, 1993) 相似文献
87.
High pressure conditions stimulate expression of chloramphenicol acetyltransferase regulated by the lac promoter in Escherichia coli 总被引:1,自引:0,他引:1
Chiaki Kato Takako Sato Maria Smorawinska Koki Horikoshi 《FEMS microbiology letters》1994,122(1-2):91-96
Abstract Recombinant plasmids with the chloramphenicol acetyltransferase (CAT) structural gene behind several kinds of promoters were tested for expression in Escherichia coli during growth at atmospheric pressure (0.1 MPa) and at high pressure (30 MPa). Expression of the CAT gene from the lac promoter was remarkably activated (approx. 78-fold) by high pressure in the absence of the inducer isopropyl-β-d-thiogalactopyranoside (IPTG). The stimulation of the CAT activity by the lac promoter at high pressure did not simply result from an increased plasmid copy number, because the CAT activities from the other promoters and β-lactamase activities were unaffected at high pressure. 相似文献
88.
Hideaki Sato Hideki Hirayama Takeshi Yamamoto Yoshimasa Lchio Fumiaki Ishizawa Michinao Mizugaki 《Luminescence》1994,9(2):73-77
The purpose of the study was to evaluate the quality of Toki-shakuyaku-san extract granules (TJ-23) using chemiluminescence (CL). A linear relationship was obtained between the log value of the CL of TJ-23 and the reaction temperature. An excellent correlation (r= 0.999) was found between the slope of this curve (ΔA) and the colour intensity due to the browning reaction occurring at the early stage of the Maillard reaction. 相似文献
89.
90.