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41.
Microtubules were purified from porcine brain by two cycles of temperature-dependent assembly and disassembly, then microtubule associated proteins, MAP-1, MAP-2, and tau, were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two-dimensional tryptic peptide maps of radioiodinated polypeptides were compared with each other by means of mixed sample experiments, and the following results were obtained. Subspecies of MAP-1 (355-345 and 325 kDa) showed about 33% homology in the tryptic peptide maps. Structural homology of MAP-1 and MAP-2 was very low; only 3 out of 40 peptide spots of MAP-2 were identical with those of MAP-1-C. Subspecies of tau proteins (65 and 60 kDa) were very closely related. Structural similarity between MAP-2 and tau was very low. MAP-1 from porcine brain and rat brain showed very high structural homology. 相似文献
42.
Gas-phase ab initio calculations indicate that dianionic pentacoordinate oxyphosphoranes do not have a kinetically meaningful intermediate. The simplest oxyphosphorane PO5H3(2-) has the least tendency to have a pentacoordinate intermediate. However, it does have a pentacoordinate intermediate when it is solvated with six water molecules. These results support the hypothesis that the phosphoryl transfer reactions take place via pentacoordinate intermediate not only in acidic but also in basic media. 相似文献
43.
Most terrestrial plants interact with diverse clades of mycorrhizal and root-endophytic fungi in their roots. Through belowground plant–fungal interactions, dominant plants can benefit by interacting with host-specific mutualistic fungi and proliferate in a community based on positive plant–mutualistic fungal feedback. On the other hand, subordinate plant species may persist in the community by sharing other sets (functional groups) of fungal symbionts with each other. Therefore, revealing how diverse clades of root-associated fungi are differentially hosted by dominant and subordinate plant species is essential for understanding plant community structure and dynamics. Based on 454-pyrosequencing, we determined the community composition of root-associated fungi on 36 co-occurring plant species in an oak-dominated forest in northern Japan and statistically evaluated the host preference phenotypes of diverse mycorrhizal and root-endophytic fungi. An analysis of 278 fungal taxa indicated that an ectomycorrhizal basidiomycete fungus in the genus Lactarius and a possibly endophytic ascomycete fungus in the order Helotiales significantly favored the dominant oak (Quercus) species. In contrast, arbuscular mycorrhizal fungi were generally shared among subordinate plant species. Although fungi with host preferences contributed to the compartmentalization of belowground plant–fungal associations, diverse clades of ectomycorrhizal fungi and possible root endophytes were associated not only with the dominant Quercus but also with the remaining plant species. Our findings suggest that dominant-ectomycorrhizal and subordinate plant species can host different subsets of root-associated fungi, and diverse clades of generalist fungi can counterbalance the compartmentalization of plant–fungal associations. Such insights into the overall structure of belowground plant–fungal associations will help us understand the mechanisms that facilitate the coexistence of plant species in natural communities. 相似文献
44.
45.
Tatsuya Ohshida Junji Hayashi Kazunari Yoneda Toshihisa Ohshima Haruhiko Sakuraba 《Proteins》2020,88(5):669-678
A gene encoding galactose 1-phosphate uridylyltransferase (GalT) was identified in the hyperthermophilic archaeon Pyrobaculum aerophilum. The gene was overexpressed in Escherichia coli, after which its product was purified and characterized. The expressed enzyme was highly thermostable and retained about 90% of its activity after incubation for 10 minutes at temperatures up to 90°C. Two different crystal structures of P. aerophilum GalT were determined: the substrate-free enzyme at 2.33 Å and the UDP-bound H140F mutant enzyme at 1.78 Å. The main-chain coordinates of the P. aerophilum GalT monomer were similar to those in the structures of the E. coli and human GalTs, as was the dimeric arrangement. However, there was a striking topological difference between P. aerophilum GalT and the other two enzymes. In the E. coli and human enzymes, the N-terminal chain extends from one subunit into the other and forms part of the substrate-binding pocket in the neighboring subunit. By contrast, the N-terminal chain in P. aerophilum GalT extends to the substrate-binding site in the same subunit. Amino acid sequence alignment showed that a shorter surface loop in the N-terminal region contributes to the unique topology of P. aerophilum GalT. Structural comparison of the substrate-free enzyme with UDP-bound H140F suggests that binding of the glucose moiety of the substrate, but not the UDP moiety, gives rise to a large structural change around the active site. This may in turn provide an appropriate environment for the enzyme reaction. 相似文献
46.
Masanori Tachikawa Kazunari Suzuki Kaoru Iguchi Tomoo Miyazaki 《Molecular simulation》2013,39(3-6):291-298
Abstract The weak interaction energy of H2 dimer is studied by double symmetry-adapted perturbation theory (SAPT) within second-order of intermolecular and intramonomer perturbation for molecular simulations. The assumed orientations of H2 dimer are linear, parallel, T type and X type. Among four orientations T orientation is the most stable, while linear orientation is the most repulsive. The second-order dispersion energy E disp (2) is the most attractive contribution in all orientations. The interaction energy has the anisotropy, so we expressed our total interaction energy by the spherical expansion to compare with the experimental value. The isotropic interaction energy is about 85% of the experimental value. 相似文献
47.
Mio Takeuchi Takeshi Komai Satoshi Hanada Hideyuki Tamaki Susumu Tanabe Yoshinori Miyachi 《Geomicrobiology journal》2013,30(2):104-118
Microbial communities in ancient marine sediments composed of clay and silt obtained from the terrestrial subsurface were phylogenetically analyzed based on their 16S rRNA gene sequences. Chloroflexi and Miscellaneous Crenarchaeotic Group were predominant in bacterial and archaeal clone libraries, respectively. Of 44 operational taxonomic units (OTUs) that had close relatives in the database, 30 were close to sequences obtained from marine environments. Some sequences belonged to the candidate groups JS1, ANME-I, and Marine Benthic Group-C, which are typically found in marine sediments. Low chloride concentrations in the sediments suggest that these marine-affiliated sequences may not reflect currently active microbial communities. Our results indicate the existence of long-term preserved DNA or descendants of ancient oceanic microbial components in subsurface muddy sediments in a temperate region, which may reflect indigenous population of paleoenvironments. 相似文献
48.
Ryan P. P. Shugg Ashley Thomson Natsuko Tanabe Adam Kashishian Bart H. Steiner Kamal D. Puri Alexey Pereverzev Brian J. Lannutti Frank R. Jirik S. Jeffrey Dixon Stephen M. Sims 《The Journal of biological chemistry》2013,288(49):35346-35357
Phosphatidylinositol 3-kinases (PI3K) participate in numerous signaling pathways, and control distinct biological functions. Studies using pan-PI3K inhibitors suggest roles for PI3K in osteoclasts, but little is known about specific PI3K isoforms in these cells. Our objective was to determine effects of isoform-selective PI3K inhibitors on osteoclasts. The following inhibitors were investigated (targets in parentheses): wortmannin and (pan-p110), PIK75 (α), GDC0941 (α, δ), TGX221 (β), AS252424 (γ), and IC87114 (δ). In addition, we characterized a new potent and selective PI3Kδ inhibitor, GS-9820, and explored roles of PI3K isoforms in regulating osteoclast function. Osteoclasts were isolated from long bones of neonatal rats and rabbits. Wortmannin, LY294002, GDC0941, IC87114, and GS-9820 induced a dramatic retraction of osteoclasts within 15–20 min to 65–75% of the initial area. In contrast, there was no significant retraction in response to vehicle, PIK75, TGX221, or AS252424. Moreover, wortmannin and GS-9820, but not PIK75 or TGX221, disrupted actin belts. We examined effects of PI3K inhibitors on osteoclast survival. Whereas PIK75, TGX221, and GS-9820 had no significant effect on basal survival, all blocked RANKL-stimulated survival. When studied on resorbable substrates, osteoclastic resorption was suppressed by wortmannin and inhibitors of PI3Kβ and PI3Kδ, but not other isoforms. These data are consistent with a critical role for PI3Kδ in regulating osteoclast cytoskeleton and resorptive activity. In contrast, multiple PI3K isoforms contribute to the control of osteoclast survival. Thus, the PI3Kδ isoform, which is predominantly expressed in cells of hematopoietic origin, is an attractive target for anti-resorptive therapeutics. LY294002相似文献
49.
Fuminori Tanabe Tomoko Nakajima Masahiko Ito 《Biochemical and biophysical research communications》2013
In Alzheimer’s disease (AD), enhancing α-secretase processing of amyloid precursor protein (APP) is an important pathway to decrease neurotoxic amyloid β (Aβ) secretion. The α-secretase is reported to be regulated by protein kinase C (PKC) and various endogenous proteins or cell surface receptors. In this report, we first examined whether Aβ reduces α-secretase activity, and showed that Aβ peptide 1–40 (0.001 and 0.01 μM) reduced the secretion of soluble amyloid precursor protein α (sAPPα) in carbachol-stimulated SH-SY5Y neuroblastoma cells. E-64-d (3 μM), which is a potent calpain inhibitor that prevents PKC degradation, ameliorated the Aβ-induced reduction of sAPPα secretion. In addition, we observed that Aβ significantly enhanced ceramide production by activating neutral sphingomyelinase. The cell-permeable ceramide analog, C2-ceramide (1 μg/mL), also reduced sAPPα secretion, and in addition, E-64-d eliminated the observed decrease of sAPPα secretion. C2-ceramide induced down-regulation of PKC-α, -β1, and -β2 isozymes in SH-SY5Y cells. These findings suggest that ceramide may play an important role in sAPPα processing by modulating PKC activity. 相似文献
50.
An enzyme, which catalyzes the isomerization of d-glucose to d-fructose, has been found in a newly isolated bacterium which tentatively identified as Pacacolobacterum aerogenoides. The enzyme converts not only d-glucose but also d-mannose to d-fructose, and NAD and Mg++ are required as cofactor for this isomerization. The properties of this enzyme were summarized as follows: (1) As a cofactor for the isomerization by this enzyme, NAD was absolutely necessary, whereas NADP, FMN and FAD were not. (2) The optimum pH was found to be at 7.5 and optinum temperature was at about 40°C. (3) The enzyme activity was markedly reduced by EDTA treatment and the reduced activity by EDTA was restored by the addition of Mg++, Mn++ or Co++. (4) The enzyme activity was strongly inhibited by monoiodoacetate, p-chloromercuribenzoate, and Cu++, however, the activity was recovered by adding cysteine or glutathione. 相似文献