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81.
Seitaro Ohkuma Hidehiko Narihara Masashi Katsura Takeshi Hasegawa Kinya Kuriyama 《Journal of neurochemistry》1995,65(3):1109-1114
Abstract: The functional significance of peroxynitrite in the release of [3 H]GABA induced by nitric oxide (NO) liberated from NO generators was investigated using cerebral cortical neurons in primary culture. NO generators such as sodium nitroprusside (SNP) and S -nitroso- N -acetylpenicillamine (SNAP) increased [3 H]GABA release in a dose-dependent manner. These increases in [3 H]GABA release were significantly inhibited by hemoglobin, indicating that those NO generators evoke the release of [3 H]GABA by the formation of NO. Two types of superoxide scavengers, Cu2+ /Zn2+ superoxide dismutase and ceruloplasmin, significantly reduced the increase in [3 H]GABA release induced by both SNP and SNAP, which assumes that NO requires superoxide to induce [3 H]GABA release from the neurons. In addition, synthesized peroxynitrite induced a dose-dependent increase in [3 H]GABA release from the neurons. These results indicate that NO-induced [3 H]GABA release is mediated by peroxynitrite formed by the reaction of NO with superoxide. 相似文献
82.
Virulent and avirulent Rhodococcus equi infection in T-cell deficient athymic nude mice: pathologic, bacteriologic and immunologic responses 总被引:1,自引:0,他引:1
83.
Elucidation of the mechanism enhancing the avidity of lectin with oligosaccharides on the solid phase surface 总被引:3,自引:2,他引:1
The mechanism underlying molecular recognition of lectins waselucidated by a novel solid phase binding assay system basedon surface plasmon resonance. When the apparent affinities ofinteractions between chitooligosaccharides and wheat germ agglutininwere compared between lectin-immobilized and oligosaccharide-immobilizedassay systems, the affinity constants (Ka) calculated for theformer system were in good agreement with the previously reportedvalues measured in solution. On the other hand, in the lattersystem, the calculated Ka could be more than 10,000 times higherthan the values in solution at lower lee tin concentrations.To elucidate the reason for this, we systematically investigatedthe effects of the oligosaccha-ride immobilized density andthe lectin valence on the apparent affinity in the oligosaccharide-immobilizedassay system. Both the apparent association (kass) and dissociationrate constants (kdiss) showed a tendency to decrease as theoligosaccharide density increased. This effect was most remarkablefor the interaction possessing an extremely fast intrinsic Kass.Oligomerization of lectin enhanced the avidity due to a significantreduction in kdiss. These phenomena could be explained by consideringthe nonhomogeneous conditions under which binding occurred.The reaction in a nonhomogeneous state is limited by the masstransport effect, and the effect of rebinding becomes so largethat it cannot be disregarded. These findings are the firstto demonstrate the importance of the mass transport effect inmodulating the affinity of lectin for oligosaccharides on asolid phase surface. avidity clustering effect lectin mass transport surface plasmon resonance 相似文献
84.
Characterization of a thermostable DNA photolyase from an extremely thermophilic bacterium, Thermus thermophilus HB27.
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The photolyase gene from Thermus thermophilus was cloned and sequenced. The characteristic absorption and fluorescence spectra of the purified T. thermophilus photolyase suggested that the protein has flavin adenine dinucleotide as a chromophore. The second chromophore binding site was not conserved in T. thermophilus photolyase. The purified enzyme showed light-dependent photoreactivation activity in vitro at 35 and 65 degrees C and was stable when subjected to heat and acidic pH. 相似文献
85.
Ayako Yamamoto Tetsuo Hashimoto Emiko Asaga Masami Hasegawa Nobuichi Goto 《Journal of molecular evolution》1997,44(1):98-105
Major parts of amino-acid-coding regions of elongation factor (EF)-1α and EF-2 in Trichomonas tenax were amplified by PCR from total genomic DNA and the products were cloned into a plasmid vector, pGEM-T. The three clones
from each of the products of the EF-1α and EF-2 were isolated and sequenced. The insert DNAs of the clones containing EF-1α
coding regions were each 1,185 bp long with the same nucleotide sequence and contained 53.1% of G + C nucleotides. Those of
the clones containing EF-2 coding regions had two different sequences; one was 2,283 bp long and the other was 2,286 bp long,
and their G + C contents were 52.5 and 52.9%, respectively. The copy numbers of the EF-1α and EF-2 gene per chromosome were
estimated as four and two, respectively.
The deduced amino acid sequences obtained by the conceptual translation were 395 residues from EF-1α and 761 and 762 residues
from the EF-2s. The sequences were aligned with the other eukaryotic and archaebacterial EF-1αs and EF-2s, respectively.
The phylogenetic position of T. tenax was inferred by the maximum likelihood (ML) method using the EF-1α and EF-2 data sets. The EF-1α analysis suggested that
three mitochondrion-lacking protozoa, Glugea plecoglossi, Giardia lamblia, and T. tenax, respectively, diverge in this order in the very early phase of eukaryotic evolution. The EF-2 analysis also supported the
divergence of T. tenax to be immediately next to G. lamblia.
Received: 15 February 1996 / Accepted: 28 June 1996 相似文献
86.
Mitochondrial DNA sequence evolution in sharks: rates, patterns, and phylogenetic inferences 总被引:8,自引:0,他引:8
Abundant representation of sharks in the fossil record makes this group a
superb system in which to investigate rates and patterns of molecular
evolution and to explore the strengths and weaknesses of phylogenetic
inferences from molecular data. In this report, the molecular evolution of
the cytochrome b gene in sharks is described and the information related to
results from phylogenetic analysis of the data evaluated in the light of a
phylogeny derived independently of the molecular data. Across divergent
lineages of sharks there is evidence for significant substitution rate
variation, departure from compositional equilibrium, and substantial
homoplasy; nevertheless, the signal of evolutionary history is evident in
patterns of shared transversions and amino acid replacements.
相似文献
87.
There is marked heterogeneity of nucleotide composition in mitochondrial
DNA across divergent animals. Differences in nucleotide composition
presumably reflect differences in directional nucleotide substitution for
A+T or G+C nucleotides. In mitochondrial DNA, there is A+T directional
nucleotide substitution in most (if not all) animals surveyed, and the
magnitude of directional A+T nucleotide substitution differs greatly within
and among groups. Differences in directional nucleotide substitution among
lineages of mammals can be explained by changes in metabolic physiology.
This relationship is thought to be mediated by the effect of oxygen
radicals because these toxic compounds are by-products of aerobic
metabolism and are known mutagens. Association between metabolism and
nucleotide composition provides additional evidence in favor of the
hypothesis that rates and patterns of nucleotide substitution in
mitochondrial DNA can be influenced by factors that impinge on rates of
endogenous DNA damage.
相似文献
88.
Shinji Hosoi Mitsuo Satoh Hiromasa Miyaji Tatsunari Nishi Tamio Mizukami Mamoru Hasegawa Seiga Itoh Tatsuya tamaoki 《Cytotechnology》1995,19(1):1-10
Pro-UKS1 was designed as a thrombin-resistant derivative of pro-urokinase (pro-UK) by introducing a glycosylation site using site-directed mutagenesis. An expression plasmid for pro-UKS1, pMo1UKS1SEd1-5, was constructed and introduced into Namalwa KJM-1 cells (Hosoiet al., 1988), and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UKS1 producer (resistant to 500 nM of MTX), clone 41-8, was selected and further characterized. Clone 41-8 was cultured in serum-free ITPSGF medium (Hosoiet al., 1988). Under the conventional conditions, the concentration of pro-UKS1 reached 26 g ml–1. Addition of glucose and tri-iodothyronine (T3) improved productivity, and the maximal productivity of pro-UKS1 was 67 g ml–1 day–1. In this conditioned medium, content of pro-UKS1 was above 80% of total proteins.Abbreviations BSA
bovine serum albumin
- dhfr
dihydrofolate reductase
- HEPES
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- kb
kilobase pairs
- kDa
kilodaltons
- MTX
Methotrexate
- PBS
phosphate buffered saline
- pro-UK
pro-urokinase
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- T3
tri-iodothyronine
- Tween-PBS
phosphate buffered saline containing 0.05% Tween 80 相似文献
89.
Immunochemical characterisation and epitope mapping of a novel fimbrial protein (Pg-II fimbria) of Porphyromonas gingivalis 总被引:2,自引:0,他引:2
Tomohiko Ogawa Kenji Yasuda Keiko Yamada Hideharu Mori Keiko Ochiai Mamoru Hasegawa 《FEMS immunology and medical microbiology》1995,11(3):247-255
Abstract Mouse monoclonal antibody (mAb) Pgf-II specific for a 72-kDa major cell-surface protein (72K-CSP) derived from Porphyromonas gingivalis OMZ 409 was prepared. Immunoblotting analysis revealed that mAb Pgf-II reacted with 72K-CSP but not with 41-kDa fimbrial subunit protein (41K-fimbrilin) derived from P. gingivalis 381. Electron microscopic observation revealed that P. gingivalis OMZ 409 possessed peritrichous, thin fimbriae on their surface. Immunogold electron microscopy also demonstrated that mAb Pgf-II bound to the 72K-CSP examined with the gold particles arranged along the fibril array originating from the cell surface of the bacteria. These findings suggested that P. gingivalis 72K-CSP was identifiable as another fimbriae (termed Pg-II fimbriae) different from the fimbriae (termed Pg-I fimbriae) composed of a 41K-fimbrilin. Using multipin peptide synthesis technology, 102 sequential overlapping peptides covering the entire 514 amino-acid stretch of Pg-II fimbriae were synthesised. Seven immunodominant regions within Pg-II fimbrial protein molecule, which definitely reacted with the serum of patients with periodontal diseases, were detected. 相似文献
90.
Biological activities of chemically synthesized analogues of the nonreducing sugar moiety of lipid A 总被引:12,自引:0,他引:12
M Matsuura Y Kojima J Y Homma Y Kubota A Yamamoto M Kiso A Hasegawa 《FEBS letters》1984,167(2):226-230
Adriamycin-Fe3+ complex catalyzes the formation of hydroxyl radical from hydrogen peroxide but the DNA-adriamycin-iron ternary complex is much more effective. 11-Deoxyadriamycin, which shows no spectral evidence of complex formation with iron, was ineffective. The generation of hydroxyl radical by adriamycin-Fe3+ complex in the presence of DNA correlates with its ability to cleave DNA. Hydroxyl radicals are thus implicated as the reactive oxygen species involved in the DNA damage caused by the adriamycin-Fe3+ complex. 相似文献