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71.
A soluble enzyme activity that attaches free diaminopimelic acid to bdelloplast peptidoglycan 总被引:1,自引:0,他引:1
An enzyme activity, responsible for the attachment of diaminopimelic acid (DAP) to bdelloplast wall peptidoglycan, was studied in an in vitro, cell-free system. Most of the activity was found in the high-speed (20000g) supernatant fraction of homogenates of bdelloplasts prepared from a culture of the intracellular bacterium Bdellovibrio bacteriovorus 109J, growing synchronously within cells of Escherichia coli. Peptidoglycan preparations obtained either from E. coli ML35 or from the walls of bdelloplasts synchronously cultured for 40 or 90 min served as the acceptors in this reaction, whereas cell wall or peptidoglycan preparations obtained from Gram-positive bacteria could not function as acceptors of DAP. The attachment activity had an apparent Km value for DAP of 10 microM; for bdelloplast peptidoglycan, it was approximately 0.43 mg/mL, which is 13 microM with respect to peptidoglycan disaccharide peptide units. DAP attachment was partially inhibited by the structural analogues lanthionine, L-ornithine, beta-aminobutyric acid, and D-serine, as well as the cell wall synthesis inhibitors penicillin G, ampicillin, and cephalexin. This enzyme activity is present only during the intracellular stage of the bdellovibrio's developmental growth cycle and may serve a stage-specific function of biochemically modifying the cell in which it grows. 相似文献
72.
Anupong Tankrathok Sakda Daduang Rina Patramanon Tomohiro Araki 《Preparative biochemistry & biotechnology》2013,43(4):380-399
Abstract In this study, four major egg white proteins were purified by two step ion exchange chromatography followed by precipitation. Lysozyme and ovalbumin were separated with Q Sepharose Fast Flow anion exchange chromatography in the first step, resulting in two peaks of lysozyme and three peaks of ovalbumin with 87% and 70% purity by HPLC, respectively. Ovotransferrin was separated with CM-Toyopearl 650 M cation exchange chromatography in the second step, giving 80% purity. Ovomucoid was precipitated from the partial purified protein fraction from the first two steps, and concentrated in the final step to yield 90% purity. Protein recoveries were estimated to be 55, 21, 54, and 21% for lysozyme, ovotransferrin, ovalbumin, and ovomuciod, respectively. Lysozyme was identified from the purified peaks using zymogram refolding gel, whereas ovalbumin was identified by western blotting. Purified ovotransferrin and ovomucoid was identified by mass spectrometry. The results indicate that this purification process is adequate for preparation of lysozyme, ovalbumin, ovotransferrin, and ovomucoid, at least on a laboratory scale. 相似文献
73.
Yoshitaka Sunami Marito Araki Yumi Hironaka Soji Morishita Masaki Kobayashi Ei Leen Liew Yoko Edahiro Miyuki Tsutsui Akimichi Ohsaka Norio Komatsu 《PloS one》2013,8(2)
Sirtuins, NAD-dependent protein deacetylases, play important roles in cellular functions such as metabolism and differentiation. Whether sirtuins function in tumorigenesis is still controversial, but sirtuins are aberrantly expressed in tumors, which may keep cancerous cells undifferentiated. Therefore, we investigated whether the inhibition of sirtuin family proteins induces cellular differentiation in leukemic cells. The sirtuin inhibitors tenovin-6 and BML-266 induce granulocytic differentiation in the acute promyelocytic leukemia (APL) cell line NB4. This differentiation is likely caused by an inhibition of SIRT2 deacetylase activity, judging from the accumulation of acetylated α-tubulin, a major SIRT2 substrate. Unlike the clinically used differentiation inducer all-trans retinoic acid, tenovin-6 shows limited effects on promyelocytic leukemia–retinoic acid receptor α (PML-RAR-α) stability and promyelocytic leukemia nuclear body formation in NB4 cells, suggesting that tenovin-6 does not directly target PML-RAR-α activity. In agreement with this, tenovin-6 induces cellular differentiation in the non-APL cell line HL-60, where PML-RAR-α does not exist. Knocking down SIRT2 by shRNA induces granulocytic differentiation in NB4 cells, which demonstrates that the inhibition of SIRT2 activity is sufficient to induce cell differentiation in NB4 cells. The overexpression of SIRT2 in NB4 cells decreases the level of granulocytic differentiation induced by tenovin-6, which indicates that tenovin-6 induces granulocytic differentiation by inhibiting SIRT2 activity. Taken together, our data suggest that targeting SIRT2 is a viable strategy to induce leukemic cell differentiation. 相似文献
74.
Pisani Luciana Pellegrini de Castro Glaucia Monteiro Ribeiro Daniel Araki 《Biological trace element research》2020,194(2):627-628
Biological Trace Element Research - 相似文献
75.
Mayumi Akizuki Hirofumi Yamashita Kengo Uemura Hirofumi Maruyama Hideshi Kawakami Hidefumi Ito Ryosuke Takahashi 《Journal of neurochemistry》2013,126(6):699-704
Mutations in more than 10 genes are reported to cause familial amyotrophic lateral sclerosis (ALS). Among these genes, optineurin (OPTN) is virtually the only gene that is considered to cause classical ALS by a loss‐of‐function mutation. Wild‐type optineurin (OPTNWT) suppresses nuclear factor‐kappa B (NF‐κB) activity, but the ALS‐causing mutant OPTN is unable to suppress NF‐κB activity. Therefore, we knocked down OPTN in neuronal cells and examined the resulting NF‐κB activity and phenotype. First, we confirmed the loss of the endogenous OPTN expression after siRNA treatment and found that NF‐κB activity was increased in OPTN‐knockdown cells. Next, we found that OPTN knockdown caused neuronal cell death. Then, overexpression of OPTNWT or OPTNE50K with intact NF‐κB‐suppressive activity, but not overexpression of ALS‐related OPTN mutants, suppressed the neuronal death induced by OPTN knockdown. This neuronal cell death was inhibited by withaferin A, which selectively inhibits NF‐κB activation. Lastly, involvement of the mitochondrial proapoptotic pathway was suggested for neuronal death induced by OPTN knockdown. Taken together, these results indicate that inappropriate NF‐κB activation is the pathogenic mechanism underlying OPTN mutation‐related ALS.
76.
Shinya Harusawa Koichi Sawada Takuji Magata Hiroki Yoneyama Lisa Araki Yoshihide Usami Kouta Hatano Kouichi Yamamoto Daisuke Yamamoto Atsushi Yamatodani 《Bioorganic & medicinal chemistry letters》2013,23(23):6415-6420
S-Alkyl-N-alkylisothiourea compounds containing various cyclic amines were synthesized in the search for novel nonimidazole histamine H3 receptor (H3R) antagonists. Among them, four N-alkyl S-[3-(piperidin-1-yl)propyl]isothioureas 18, 19, 22, and 23 were found to exhibit potent and selective H3R antagonistic activities against in vitro human H3R, but were inactive against in vitro human H4R. Furthermore, three alkyl homologs 18–20 showed inactivity for histamine release in in vivo rat brain microdialysis, suggesting differences in antagonist affinities between species. In addition, in silico docking studies of N-[4-(4-chlorophenyl)butyl]-S-[3-piperidin-1-yl)propyl]isothiourea 19 and a shorter homolog 17 with human/rat H3Rs revealed that structural differences between the antagonist-docking cavities of rat and human H3Rs were likely caused by the Ala122/Val122 mutation. 相似文献
77.
Shigemitsu Matsumoto Naoki Miyamoto Takaharu Hirayama Hideyuki Oki Kengo Okada Michiko Tawada Hidehisa Iwata Kazuhide Nakamura Seiji Yamasaki Hiroshi Miki Akira Hori Shinichi Imamura 《Bioorganic & medicinal chemistry》2013,21(24):7686-7698
To identify compounds with potent antitumor efficacy for various human cancers, we aimed to synthesize compounds that could inhibit c-mesenchymal epithelial transition factor (c-Met) and vascular endothelial growth factor receptor 2 (VEGFR2) kinases. We designed para-substituted inhibitors by using co-crystal structural information from c-Met and VEGFR2 in complex with known inhibitors. This led to the identification of compounds 3a and 3b, which were capable of suppressing both c-Met and VEGFR2 kinase activities. Further optimization resulted in pyrazolone and pyridone derivatives, which could form intramolecular hydrogen bonds to enforce a rigid conformation, thereby producing potent inhibition. One compound of particular note was the imidazo[1,2-a]pyridine derivative (26) bearing a 6-methylpyridone ring, which strongly inhibited both c-Met and VEGFR2 enzyme activities (IC50 = 1.9, 2.2 nM), as well as proliferation of c-Met-addicted MKN45 cells and VEGF-stimulated human umbilical vein endothelial cells (IC50 = 5.0, 1.8 nM). Compound 26 exhibited dose-dependent antitumor efficacy in vivo in MKN45 (treated/control ratio [T/C] = 4%, po, 5 mg/kg, once-daily) and COLO205 (T/C = 13%, po, 15 mg/kg, once-daily) mouse xenograft models. 相似文献
78.
79.
Tomohide Uno Kazuki Sakamoto Yuri Isoyama Susumu Hiragaki Yuichi Uno Kengo Kanamaru Hiroshi Yamagata Michihiro Takagi Akira Mizoguchi Makio Takeda 《Histochemistry and cell biology》2013,139(2):299-308
Rab proteins are small GTPases that play essential roles in vesicle transport. In this study, we examined the expression of Rab proteins and neuropeptide hormones in the brain of the silkworm, Bombyx mori. We produced antibodies against B. mori Rab1 and Rab14 in rabbits. Immunoblotting of samples of brain tissue from B. mori revealed a single band for each antibody. Rab1 and Rab14 immunohistochemical labeling in the brain of B. mori was restricted to neurons of the pars intercerebralis and dorsolateral protocerebrum. Rab1, Rab7 and Rab14 co-localized with bombyxin. Rab1 and Rab7 co-localized with eclosion hormone. Rab1 co-localized with prothoracicotropic hormone. These results suggest that Rab1, Rab7 and Rab14 may be involved in neuropeptide transport in the brain of B. mori. This is the first report on the specificity of Rab proteins for the secretion of different neuropeptides in insects. 相似文献
80.
Shuichi Ishino Kazuo Yamaguchi Kunikatsu Shirahata Kazumi Araki 《Bioscience, biotechnology, and biochemistry》2013,77(10):2557-2560
To characterize aspartyl aminopeptidase from Aspergillus oryzae, the recombinant enzyme was expressed in Escherichia coli. The enzyme cleaves N-terminal acidic amino acids. About 30% activity was retained in 20% NaCl. Digestion of defatted soybean by the enzyme resulted in an increase in the glutamic acid content, suggesting that the enzyme is potentially responsible for the release of glutamic acid in soy sauce mash. 相似文献