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41.
Takushi Nagata Kiyomi Imagawa Tohru Yamada
Teruaki Mukaiyama
《Inorganica chimica acta》1994,220(1-2):283-287A novel manganese(III) complex having an optically active N, N′-ethylenebis-β-ketoimine ligand was prepared and characterized crystallographically. The manganese(III) complexes behave as effective catalysts in enantioselective epoxidation of unfunctionalized olefins by combined use of molecular oxygen, an oxidant, and pivalaldehyde, a reductant. Dihydronaphthalene derivatives were converted into the corresponding optically active epoxides with good to high enantioselectivities. 相似文献
42.
Human alpha-3-N-acetylgalactosaminyltransferase has been purified 27,000,000-fold from A1 plasma by (NH4)2SO4 fractionation and affinity chromatography on Sepharose 4B, anti-human group O plasma antibodies-Sepharose 4B, and Blue Dextran-Sephadex G-25. A modified procedure in the Sepharose 4B step was developed by batch adsorption and desorption experiments. Cibacron Blue F3G-A, the chromophore of Blue Dextran, was found to bind to the enzyme. UDP is an effective inhibitor of this binding. The pure transferase has an apparent molecular weight of 35,000 as judged by SDS-PAGE in the presence of a reducing agent. The specific activity is 16 pmol/min.ng enzyme, which is comparable to that (30 pmol/min.ng enzyme) of alpha-3-N-acetylgalactosaminyltransferase from porcine submaxillary glands [Schwyzer and Hill (1977) J. Biol. Chem. 252, 2338-2355]. The apparent Km values for UDP-GalNAc, 2'-fucosyllactose, and lacto-N-fucopentaose I are 13, 270, and 350 microM, respectively. The reaction velocity was found to fall off again at high concentrations of oligosaccharide acceptor substrates. The apparent Ki values for UDP and UDP-galactose are 8.6 and 6.2 microM, respectively. The pure enzyme also catalyzes the transfer of galactose in alpha-linkage to 2'-fucosyllactose though the transfer rate of galactose is much lower than that of N-acetylgalactosamine. 相似文献
43.
Human blood group O plasma was found to contain an N-acetylgalactosaminyltransferase which catalyzes the transfer of N-acetylgalactosamine from UDP-GalNAc to Gal beta 1-->4Glc, Gal beta 1-->4GlcNAc, asialo-alpha 1-acid glycoprotein, and Gal beta 1-->4GlcNAc beta 1-->3Gal beta 1-->4Glc-ceramide, but not to Gal beta 1-->3GlcNAc. The enzyme required Mn2+ for its activity and showed a pH optimum at 7.0. The reaction products were readily hydrolyzed by beta-N-acetylhexosaminidase and released N-acetylgalactosamine. Apparent Km values for UDP-GalNAc, Mn2+, lactose, N-acetyllactosamine, and terminal N-acetyllactosaminyl residues of asialo-alpha 1-acid glycoprotein were 0.64, 0.28, 69, 20, and 1.5 mM, respectively. Studies on acceptor substrate competition indicated that all the acceptor substrates mentioned above compete for one enzyme, whereas the enzyme can be distinguished from an NeuAc alpha 2-->3Gal beta-1,4-N-acetylgalactosaminyltransferase, which also occurs in human plasma. The methylation study of the product formed by the transfer of N-acetylgalactosamine to lactose revealed that N-acetylgalactosamine had been transferred to the carbon-3 position of the beta-galactosyl residue. Although the GalNAc beta 1-->3Gal structure is known to have the blood group P antigen activity, human plasma showed no detectable activity of Gal alpha 1-->4Gal beta-1,3-N-acetylgalactosaminyltransferase, which is involved in the synthesis of the major P antigen-active glycolipid, GalNAc beta 1-->3Gal alpha 1-->4Gal beta 1-->4Glc-ceramide. Hence, the GalNAc beta 1-->3Gal beta 1-->4GlcNAc/Glc structure is synthesized by the novel Gal beta 1-->4GlcNAc/Glc beta-1,3-N-acetylgalactosaminyltransferase. 相似文献
44.
High-rate nitrogen removal from waste brine by marine anammox bacteria in a pilot-scale UASB reactor
Yokota Nobuyuki Watanabe Yasutsugu Tokutomi Takaaki Kiyokawa Tomohiro Hori Tomoyuki Ikeda Daisuke Song Kang Hosomi Masaaki Terada Akihiko 《Applied microbiology and biotechnology》2018,102(3):1501-1512
Applied Microbiology and Biotechnology - The goal of this study was to develop a startup strategy for a high-rate anaerobic ammonium oxidation (anammox) reactor to treat waste brine with high... 相似文献
45.
Masayuki Nakao Yuji Nishiuchi Makoto Nakata Takushi X. Watanabe Terutoshi Kimura Shumpei Sakakibara 《Letters in Peptide Science》1995,2(1):17-26
Summary Conotoxin GS, a -carboxyglutamic acid(Gla)-containing neurotoxic peptide composed of 34 amino acid residues with one Gla residue and three intramolecular disulfide bonds, was synthesized in solution by the Boc strategy, using the cyclohexyl group to protect the ,-dicarboxyl functional side chain of the Gla residue. All of the protecting groups were removed by the HF procedure. During the synthesis, the Gla residue was completely stable and decarboxylated product was observed. The free peptide was subjected to the oxidative folding reaction. The reaction proceeded almost quantitatively in the presence of reduced and oxidized glutathione; however, no product was formed in the absence of redox reagents concomitant with the formation of disulfide isomers or intermediates. The final product was confirmed to be identical to natural conotoxin GS on reversed phase- and ion exchange-HPLC as well as capillary zone electrophoresis. The disulfide structure of synthetic conotoxin GS was determined by gas-phase sequencing and mass spectrometry of its proteolytic fragments and was found to be identical to those of other -conotoxins. The major disulfide isomer obtained during the oxidative folding reaction without redox reagents was determined in the same manner. To clarify the role of the Gla residue and the disulfide structure in the conotoxin GS molecule, decarboxylated conotoxin GS and its disulfide isomer were also synthesized, and the neurotoxic activities and circular dichroism spectra of these peptides were compared with those of conotoxin GS and its disulfide isomer. The results showed that the correct disulfide structure was necessary for expression of the toxicity; however, the presence of the Gla residue was not a prerequisite for both the activity and the calcium-dependent conformational transition. 相似文献
46.
Human serum was shown to contain N-acetyllactosamine: N-acetylglucosaminyltransferase activity. The reaction product was hydrolyzed by beta-N-acetylglucosaminidase and released [14C]N-acetylglucosamine, indicating that the N-acetylglucosaminyl residue was beta-linked to N-acetyllactosamine. Methylation and hydrolysis of the reaction product yielded 2,4,6-trimethyl[3H]galactose, indicating that the N-acetylglucosaminyl residue was introduced at position C-3 of the terminal galactose of N-acetyllactosamine. In our experiments, 2,3,4-trimethyl[3H]galactose was not detected. Substrate competition studies between N-acetyllactosamine and lactose showed that this enzyme also catalyzed the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to lactose. Since the Km value for N-acetyllactosamine, which was 7.0 mM, was approximately a fourth of that for lactose (29.8 mM), N-acetyllactosamine was more effective than lactose as an acceptor. 相似文献
47.
48.
Daisuke Oikawa Min Gi Hidetaka Kosako Kouhei Shimizu Hirotaka Takahashi Masayuki Shiota Shuhei Hosomi Keidai Komakura Hideki Wanibuchi Daisuke Tsuruta Tatsuya Sawasaki Fuminori Tokunaga 《Cell death & disease》2022,13(8)
Deubiquitinating enzymes (DUBs) regulate numerous cellular functions by removing ubiquitin modifications. We examined the effects of 88 human DUBs on linear ubiquitin chain assembly complex (LUBAC)-induced NF-κB activation, and identified OTUD1 as a potent suppressor. OTUD1 regulates the canonical NF-κB pathway by hydrolyzing K63-linked ubiquitin chains from NF-κB signaling factors, including LUBAC. OTUD1 negatively regulates the canonical NF-κB activation, apoptosis, and necroptosis, whereas OTUD1 upregulates the interferon (IFN) antiviral pathway. Mass spectrometric analysis showed that OTUD1 binds KEAP1, and the N-terminal intrinsically disordered region of OTUD1, which contains an ETGE motif, is indispensable for the KEAP1-binding. Indeed, OTUD1 is involved in the KEAP1-mediated antioxidant response and reactive oxygen species (ROS)-induced cell death, oxeiptosis. In Otud1−/−-mice, inflammation, oxidative damage, and cell death were enhanced in inflammatory bowel disease, acute hepatitis, and sepsis models. Thus, OTUD1 is a crucial regulator for the inflammatory, innate immune, and oxidative stress responses and ROS-associated cell death pathways.Subject terms: Stress signalling, Cell death, Inflammation 相似文献
49.
50.
Takushi Tadakuma 《Microbiology and immunology》1972,16(4):287-296
Restoration of impaired antibody response to sheep red blood cells (SRBC) in spleen cell cultures from mice treated with heterologous antilymphocyte globulin (ALG) was studied by adding normal cells from various sources, to explore the problems of cell-cooperation in anti-SRBC antibody response and the target of ALG. When spleen cells from ALG-treated mice were separated into macrophage-rich and lymphoid cell-rich subpopulations, only the latter was found to be impaired in the ability for anti-SRBC antibody response. Addition of even a small number of normal allogeneic spleen cells sufficiently restored the impaired anti-SRBC antibody response of the spleen cells from ALG-treated mice. By use of allo-antisera, most hemolysin plaque-forming cells (PFC) generated in such cultures were proved to be derived from the cells of ALG-treated mice. Restoration was also achieved by adding thymus-derived cells, which were obtained from spleens of mice heavily irradiated and repopulated with syngeneic thymus cells, or lymphoid cells directly collected from thymuses. All results indicate that ALG selectively depletes the thymus-derived antigen reactive cells (ARC) in the spleen cell population, and that ARC supplied from normal spleen or thymus can interact with plaque-forming cell precursors (PFCP) that remain intact in the spleen cell population of ALG-treated mice. The results also suggest that a single ARC interacts with more than one PFCP and makes them develop into PFC. 相似文献