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41.
Maeda H Kakoki N Ayabe M Koga Y Oribe T Matsuo Y Tanaka T Kouno I 《Phytochemistry》2011,72(8):796-803
ent-Eudesmane sesquiterpenoids, 8,11-dihydroxy-2,4-cycloeudesmane, 11-hydroxy-2,4-cycloeudesman-8-one and 2,4-cyclo-7(11)-eudesmen-8-one, were isolated from the wood of Platycarya strobilacea, which has been used as an aromatic tree since at least the 18th century. On charring the wood, 2,4-cyclo-7(11)-eudesmen-8-one was detected in the smoke. In the charred wood, the concentrations of ellagitannins, such as galloyl pedunculagin, dramatically decreased, whereas concentrations of pentagalloyl glucose, and other gallotannins were relatively stable. In addition, two other compounds, the 6′-O-m- and p-digalloyl oak lactone precursor and the 3-O-methylellagic acid 4′-O-(4″-O-galloyl)-xylopyranoside, were isolated from the charred wood along with m- and p-digallic acid. 相似文献
42.
Tanaka M Machida Y Nishikawa Y Akagi T Morishima I Hashikawa T Fujisawa T Nukina N 《Biochemistry》2002,41(32):10277-10286
To examine the effects of aggregation-inducing motifs related to neurodegenerative diseases on amyloid formation of host protein, we prepared several chimera myoglobins, in which various aggregation-inducing motifs were inserted. The focused aggregation-inducing motifs included five (R5) or two (R2) oligopeptide repeats in yeast Sup35p, five octapeptide repeats (OPR) in the human prion protein, a nonamyloid beta component (NAC) in alpha-synuclein, and tandem repeats of 50 glutamines (Q50). Circular dichroism and infrared spectroscopies suggested that the OPR, R5, and Q50 motifs formed an antiparallel beta sheet as well as a random coil, whereas the R2 and NAC motifs mainly formed random coils. The OPR, R5, and Q50 mutants, but not the R2 and NAC mutants, readily formed the SDS-resistant aggregates under physiological condition, and electron microscopy revealed that the aggregates contained amyloid fibrils. The destabilization and increase in gyration radius of the OPR, R5, and Q50 mutants correlated with the tendency to form amyloid fibrils. A control mutant bearing a nonamyloidgenic sequence was also moderately destabilized but did not form amyloid fibrils. Therefore, we concluded that the OPR, R5, and Q50 motifs, even in a quite stable protein such as myoglobin, led the host protein to formation of amyloid fibrils under physiological condition. 相似文献
43.
Toshitaka Nakamura Motoyuki Ogawa Kazuki Kojima Saki Takayanagi Shunya Ishihara Kazuki Hattori Isao Naguro Hidenori Ichijo 《EMBO reports》2021,22(5)
Ferroptosis has recently attracted much interest because of its relevance to human diseases such as cancer and ischemia‐reperfusion injury. We have reported that prolonged severe cold stress induces lipid peroxidation‐dependent ferroptosis, but the upstream mechanism remains unknown. Here, using genome‐wide CRISPR screening, we found that a mitochondrial Ca2+ uptake regulator, mitochondrial calcium uptake 1 (MICU1), is required for generating lipid peroxide and subsequent ferroptosis under cold stress. Furthermore, the gatekeeping activity of MICU1 through mitochondrial calcium uniporter (MCU) is suggested to be indispensable for cold stress‐induced ferroptosis. MICU1 is required for mitochondrial Ca2+ increase, hyperpolarization of the mitochondrial membrane potential (MMP), and subsequent lipid peroxidation under cold stress. Collectively, these findings suggest that the MICU1‐dependent mitochondrial Ca2+ homeostasis‐MMP hyperpolarization axis is involved in cold stress‐induced lipid peroxidation and ferroptosis. 相似文献
44.
Noritsugu Yabe Yutaka Matsuya Isao Yamane Mitsuru Takada 《In vitro cellular & developmental biology. Plant》1986,22(7):363-368
Summary A newly developed, serum-free medium (NYSF-404) selects for antibody-producing hybridomas after fusion of antigen-sensitized
mouse spleen cells with myeloma cell lines P3-X63-Ag8-U1 (P3-U1), P3-X63-Ag8-6.5.3 (Ag8.653), or P3-NSI/1-Ag4-1 (NS-1). Without
the need for hypoxanthine-aminopterinthymidine (HAT) selection of hybrid cells, frequency of hybridoma formation in medium
NYSF-404 is higher (twice) than that in serum- and HAT-containing medium. Colonies developed upon limiting dilution in the
presence of the mortal parent myeloma cells in medium NYSF-404 and pure culture of antibody-secreting cells could be subsequently
established. The results suggest that fusions can be done in serum-free medium and that the clonal growth of hybridomas is
dependent on factors produced by parent myeloma cells under serum-free culture conditions. Such factors seem deficient in
serum- and HAT-containing medium or are masked by serum. 相似文献
45.
Yoshiko Hanaoka Fumihiko Takebe Yoshinobu Nodasaka Isao Hara Hidetoshi Matsuyama Isao Yumoto 《PloS one》2013,8(10)
A psychrotolerant and H2O2-resistant bacterium, Exiguobacterium oxidotolerans T-2-2T, exhibits extraordinary H2O2 resistance and produces catalase not only intracellularly but also extracellularly. The intracellular and extracellular catalases exhibited the same enzymatic characteristics, that is, they exhibited the temperature-dependent activity characteristic of a cold-adapted enzyme, their heat stabilities were similar to those of mesophilic enzymes and very high catalytic intensity. In addition, catalase gene analysis indicated that the bacterium possessed the sole clade 1 catalase gene corresponding to intracellular catalase. Hence, intracellular catalase is secreted into the extracellular space. In addition to intracellular and extracellular catalases, the inner circumference of the cells showed the localization of catalase in the mid-stationary growth phase, which was observed by immunoelectron microscopy using an antibody against the intracellular catalase of the strain. The cells demonstrated higher catalase activity in the mid-stationary growth phase than in the exponential growth phase. The catalase localized in the inner circumference can be dissociated by treatment with Tween 60. Thus, the localized catalase is not tightly bound to the inner circumference of the cells and may play a role in the oxidative defense of the cells under low metabolic state. 相似文献
46.
47.
Ryo Nagao Akira Moriguchi Tatsuya Tomo Ayako Niikura Saori Nakajima Takehiro Suzuki Akinori Okumura Masako Iwai Jian-Ren Shen Masahiko Ikeuchi Isao Enami 《The Journal of biological chemistry》2010,285(38):29191-29199
Oxygen-evolving photosystem II (PSII) isolated from a marine centric diatom, Chaetoceros gracilis, contains a novel extrinsic protein (Psb31) in addition to four red algal type extrinsic proteins of PsbO, PsbQ′, PsbV, and PsbU. In this study, the five extrinsic proteins were purified from alkaline Tris extracts of the diatom PSII by anion and cation exchange chromatographic columns at different pH values. Reconstitution experiments in various combinations with the purified extrinsic proteins showed that PsbO, PsbQ′, and Psb31 rebound directly to PSII in the absence of other extrinsic proteins, indicating that these extrinsic proteins have their own binding sites in PSII intrinsic proteins. On the other hand, PsbV and PsbU scarcely rebound to PSII alone, and their effective bindings required the presence of all of the other extrinsic proteins. Interestingly, PSII reconstituted with Psb31 alone considerably restored the oxygen evolving activity in the absence of PsbO, indicating that Psb31 serves as a substitute in part for PsbO in supporting oxygen evolution. A significant difference found between PSIIs reconstituted with Psb31 and with PsbO is that the oxygen evolving activity of the former is scarcely stimulated by Cl− and Ca2+ ions but that of the latter is largely stimulated by these ions, although rebinding of PsbV and PsbU activated oxygen evolution in the absence of Cl− and Ca2+ ions in both the former and latter PSIIs. Based on these results, we proposed a model for the association of the five extrinsic proteins with intrinsic proteins in diatom PSII and compared it with those in PSIIs from the other organisms. 相似文献
48.
49.
Ohara C Takahashi R Miyagawa T Yoshimura Y Kato A Adachi I Takahata H 《Bioorganic & medicinal chemistry letters》2008,18(6):1810-1813
A highly practicable synthesis of both enantiomers of 3-hydroxypipecolic acid derivatives 1, 2, 3, 4 is described. Screening of these molecules for glycosidase inhibition has been examined. Compound 3 was shown to be a potent inhibitor of beta-N-acetylglucosaminidase as well as Escherichia coli beta-glucuronidase. 相似文献
50.
Sugiyama S Di Nardo AA Aizawa S Matsuo I Volovitch M Prochiantz A Hensch TK 《Cell》2008,134(3):508-520
Neural circuits are shaped by experience in early postnatal life. Distinct GABAergic connections within visual cortex determine the timing of the critical period for rewiring ocular dominance to establish visual acuity. We find that maturation of the parvalbumin (PV)-cell network that controls plasticity onset is regulated by a selective re-expression of the embryonic Otx2 homeoprotein. Visual experience promoted the accumulation of non-cell-autonomous Otx2 in PV-cells, and cortical infusion of exogenous Otx2 accelerated both PV-cell development and critical period timing. Conversely, conditional removal of Otx2 from non-PV cells or from the visual pathway abolished plasticity. Thus, the experience-dependent transfer of a homeoprotein may establish the physiological milieu for postnatal plasticity of a neural circuit. 相似文献