Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society of Applied Glycoscience  

DOI： 10.5458/jag.jag.jag-2020_0005

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Language：English  

The pathogenic fungus Aspergillus fumigatus contains galactomannans localized on the surface layer of its cell walls, which are involved in various biological processes. Galactomannans comprise α-(1→2)-/α-(1→6)-mannan and β-(1→5)-/β-(1→6)-galactofuranosyl chains. We previously revealed that GfsA is a β-galactofuranoside β-(1→5)-galactofuranosyltransferase involved in the biosynthesis of β-(1→5)-galactofuranosyl chains. In this study, we clarified the biosynthesis of β-(1→5)-galactofuranosyl chains in A. fumigatus Two paralogs exist within A. fumigatus: GfsB and GfsC. We show that GfsB and GfsC, in addition to GfsA, are β-galactofuranoside β-(1→5)-galactofuranosyltransferases by biochemical and genetic analyses. GfsA, GfsB, and GfsC can synthesize β-(1→5)-galactofuranosyl oligomers at up to lengths of 7, 3, and 5 galactofuranoses within an established in vitro highly efficient assay of galactofuranosyltransferase activity. Structural analyses of galactomannans extracted from ΔgfsB, ΔgfsC, ΔgfsAC, and ΔgfsABC strains revealed that GfsA and GfsC synthesized all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans and that GfsB exhibited limited function in A. fumigatus The loss of β-(1→5)-galactofuranosyl residues decreased the hyphal growth rate and conidium formation ability and increased the abnormal hyphal branching structure and cell surface hydrophobicity, but this loss is dispensable for sensitivity to antifungal agents and virulence toward immunocompromised mice.IMPORTANCE β-(1→5)-Galactofuranosyl residues are widely distributed in the subphylum Pezizomycotina of the phylum Ascomycota. Pezizomycotina includes many plant and animal pathogens. Although the structure of β-(1→5)-galactofuranosyl residues of galactomannans in filamentous fungi was discovered long ago, it remains unclear which enzyme is responsible for biosynthesis of this glycan. Fungal cell wall formation processes are complicated, and information concerning glycosyltransferases is essential for understanding them. In this study, we showed that GfsA and GfsC are responsible for the biosynthesis of all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans. The data presented here indicate that β-(1→5)-galactofuranosyl residues are involved in cell growth, conidiation, polarity, and cell surface hydrophobicity. Our new understanding of β-(1→5)-galactofuranosyl residue biosynthesis provides important novel insights into the formation of the complex cell wall structure and the virulence of the members of the subphylum Pezizomycotina.

DOI： 10.1128/mSphere.00770-19

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.carres.2019.01.005

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Institute of Heterocyclic Chemistry  

DOI： 10.3987/com-18-14002

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURAL PRODUCTS INC  

Reaction of 3,4,6-tri-O-acetyl-a-glucal with silver 4-nitrophenolate in the presence of N-iodosuccinimide and N-bromosuccinimide produced (2,6-dihalo-4-nitro)phenyl 2-halo-2-deoxy-alpha-D-glycopyranosides. Although bromination and iodination of the 4-nitrophenyl group could not be avoided, the resulting (2,6-dihalo-4-nitro)phenylated compounds can be used as substrates or covalent glycosidase inhibitors after deprotection. The stereoselectivity and regioselectivity of the halogenation reactions are described.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The design, synthesis and application of N-acetylneuraminic acid-derived compounds bearing anomeric sulfo functional groups are described. These novel compounds, which we refer to as sulfo-sialic acid analogues, include 2-decarboxy-2-deoxy-2-sulfo-N-acetylneuraminic acid and its 4-deoxy-3,4-dehydrogenated pseudoglycal. While 2-decarboxy-2-deoxy-2-sulfo-N-acetylneuraminic acid contains no further modifications of the 2-deoxy-pyranose ring, it is still a more potent inhibitor of avian-origin H5N1 neuraminidase (NA) and drug-resistant His275Tyr NA as compared to the oxocarbenium ion transition state analogue 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. The sulfo-sialic acid analogues described in this report are also more potent inhibitors of influenza NA (up to 40-fold) and bacterial NA (up to 8.5-fold) relative to the corresponding anomeric phosphonic acids. These results confirm that this novel anomeric sulfo modification offers great potential to improve the potency of next-generation NA inhibitors including covalent inhibitors.

DOI： 10.1038/s41598-017-07836-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS INC  

Previously, we reported that GfsA is a novel galactofuranosyltransferase involved in the biosynthesis of O-glycan, the proper maintenance of fungal morphology, the formation of conidia and anti-fungal resistance in Aspergillus nidulans and A. fumigatus (Komachi Y et al., 2013. GfsA encodes a novel galactofuranosyltransferase involved in biosynthesis of galactofuranose antigen of O-glycan in Aspergillus nidulans and Aspergillus fumigatus. Mol. Microbiol. 90:1054-1073). In the present paper, to gain an in depth-understanding of the enzymatic functions of GfsA in A. fumigatus (AfGfsA), we established an in vitro assay to measure galactofuranosyltransferase activity using purified AfGfsA, UDP-alpha-d-galactofuranose as a sugar donor, and p-nitrophenyl-beta-d-galactofuranoside as an acceptor substrate. LC/MS, H-1-NMR and methylation analyses of the enzymatic products of AfGfsA revealed that this protein has the ability to transfer galactofuranose to the C-5 position of the beta-galactofuranose residue via a beta-linkage. AfGfsA requires a divalent cation of manganese for maximal activity and consumes UDP-alpha-d-galactofuranose as a sugar donor. Its optimal pH range is 6.5-7.5 and its optimal temperature range is 20-30A degrees C. H-1-NMR, C-13-NMR and methylation analyses of fungal-type galactomannan extracted from the a dagger AfgfsA strain revealed that AfGfsA is responsible for the biosynthesis of beta 1,5-galactofuranose in the galactofuran side chain of fungal-type galactomannan. Based on these results, we conclude that AfGfsA acts as a UDP-alpha-d-galactofuranose: beta-d-galactofuranoside beta 1,5-galactofuranosyltransferase in the biosynthetic pathway of galactomannans.

DOI： 10.1093/glycob/cwx028

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURAL PRODUCTS INC  

TMSCl works as an acid catalyst precursor for selective esterification of L-aspartic and L-glutamic acids in the presence of primary, secondary and tertiary alcohols. Although excess TMSCl was required for the completion of esterification, the resulting alkyl TMS ether could be azeotropically removed by simple evaporation with alcohol.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WALTER DE GRUYTER GMBH  

The spiroacetal [C(9)-C(20)] fragments of spirofungins A and B, antibiotics isolated from Streptomyces violaceusniger Tu 4113, were prepared from a known bromo alcohol derived from (S)-citronellal, using thermodynamically controlled iodolactonization and spiroacetalization as the key steps.

DOI： 10.1515/hc-2015-0193

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

beta-D-galactofuranose (Galf) is a component of polysaccharides and glycoconjugates and its transferase has been well analyzed. However, no beta-D-galactofuranosidase (Galf-ase) gene has been identified in any organism. To search for a Galf-ase gene we screened soil samples and discovered a strain, identified as a Streptomyces species by the 16S ribosomal RNA gene analysis, that exhibits Galf-ase activity for 4-nitrophenyl beta-D-galactofuranoside (pNP-beta-D-Galf) in culture supernatants. By draft genome sequencing of the strain, named JHA19, we found four candidate genes encoding Galf-ases. Using recombinant proteins expressed in Escherichia coli, we found that three out of four candidates displayed the activity of not only Galf-ase but also alpha-L-arabinofuranosidase (Araf-ase), whereas the other one showed only the Galf-ase activity. This novel Galf-specific hydrolase is encoded by ORF1110 and has an optimum pH of 5.5 and a Km of 4.4 mM for the substrate pNP-beta-D-Galf. In addition, this enzyme was able to release galactose residue from galactomannan prepared from the filamentous fungus Aspergillus fumigatus, suggesting that natural polysaccharides could be also substrates. By the BLAST search using the amino acid sequence of ORF1110 Galf-ase, we found that there are homolog genes in both prokaryotes and eukaryotes, indicating that Galf-specific Galf-ases widely exist in microorganisms.

DOI： 10.1371/journal.pone.0137230

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A novel and practical oxidation of alcohols to carbonyl compounds using NaOCl in the presence of catalytic amounts of imide compound and nitroxyl radical has been developed. A wide variety of aliphatic, benzylic primary alcohols, and secondary alcohols were oxidized to afford the corresponding aldehydes and ketones in up to 98% yield without undesired halogenation on aromatic rings or double bonds. The oxidation safely proceeded not only in the presence of K2CO3 but also by a slow addition of NaOCl without tedious pH adjustment. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2015.04.115

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The Pictet-Spengler reaction between tryptamine and aldehydes was catalyzed by Dowex 50W-X4 acidic ion-exchange resin. The products were obtained from the resin in high purity by 'catch and release' without the need for separate chromatographic purification.

DOI： 10.1271/bbb.100770

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca(2+)-releasing messenger. Biological data suggest that its receptor has two binding sites: one high-affinity locking site and one low-affinity opening site. To directly address the presence and function of these putative binding sites, we synthesized and tested analogues of the NAADP antagonist Ned-19. Ned-19 itself inhibits both NAADP-mediated Ca(2+) release and NAADP binding. A fluorometry bioassay was used to assess NAADP-mediated Ca(2+) release, whereas a radioreceptor assay was used to assess binding to the NAAD Preceptor (only at the high-affinity site). In Ned-20, the fluorine is para rather than ortho as in Ned-19. Ned-20 does not inhibit NAADP-mediated Ca(2+) release but inhibits NAADP binding. Conversely, Ned-19.4 (a methyl ester of Ned-19) inhibits NAADP-mediated Ca(2+) release but cannot inhibit NAADP binding. Furthermore, Ned-20 prevents the self-desensitization response characteristic of NAADP in sea urchin eggs, confirming that this response is mediated by a high-affinity allosteric site to which NAADP binds in the radioreceptor assay. Collectively, these data provide the first direct evidence for two binding sites (one high-and one low affinity) on the NAADP receptor.

DOI： 10.1074/jbc.M109.016519

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

The reaction of trioxane and tetraoxane endoperoxides with unsaturated phospholipid I in the presence of Fe(II) was investigated in the absence of oxygen by means of tandem ESI-MS analysis. The spectral analyses for the reaction mixtures showed that artemisinin 2 with a trioxane structure gave no peak except that for the remaining intact phospholipid 1 (m/z 758.9), indicating that there was no structural change to 1. On other hand, the reaction mixture of I with tetraoxanes 3 and 4 afforded a number of new peaks (m/z 620-850) that were presumably assigned to oxidative degradation products originating from phospholipid 1. Since this reaction was completely inhibited by the addition of a phenolic antioxidant. the process was considered to involve some free radical species. The newly discovered marked differences in reactivity between the trioxane and the tetraoxanes possibly reflects their different anti-malarial mechanisms, and this reactivity may contribute to the classification of a number of anti-malarial endoperoxides whose mode of action is based on phospholipid oxidation. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.chemphyslip.2009.04.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Phospholipase D (PLD) is a biocatalyst in the synthesis of bioactive compounds and a key enzyme in a variety of biological signal transductions. A combination of unnatural phosphatidyl acceptor, N,N,N-triethyl-N-2-hydroxyethylammonium bromide 6, as a substrate for PLD, and tandem electrospray ionization mass spectrometry (ESI MS) was found to provide information as to whether a given phospholipid serves as a substrate for the PLD-catalyzed reaction. Thus 2-(13′-hydroperoxy-octadecadienoyl)-1-palmitoylglycerophosphocholine 1, and its degradation products 2-(13′-oxo-octadecadienoyl)-1-palmitoylglycerophosphocholine 9 and 2-(13′-hydroxy-octadecadienoyl)-1-palmitoylglycerophosphocholine 11, in a mixture were found to be a substrate of the PLD-catalyzed transphosphatidylation. The sensitivity of this method was exemplified by the observation that PLD activity in cabbage leaves was detected using a small amount of crude crushed leaves with little pretreatment. This simple method can be used in screening for PLD activity and searching for inhibitors of the enzyme from various natural sources.

DOI： 10.1271/bbb.90093

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Research into the biological role of the Ca(2+)-releasing second messenger NAADP (nicotinic acid adenine dinucleotide phosphate) has been hampered by a lack of chemical probes. To find new chemical probes for exploring NAADP signaling, we turned to virtual screening, which can evaluate millions of molecules rapidly and inexpensively. We used NAADP as the query ligand to screen the chemical library ZINC for compounds with similar three-dimensional shape and electrostatic properties. We tested the top-ranking hits in a sea urchin egg bioassay and found that one hit, Ned-19, blocks NAADP signaling at nanomolar concentrations. In intact cells, Ned-19 blocked NAADP signaling and fluorescently labeled NAADP receptors. Moreover, we show the utility of Ned-19 as a chemical probe by using it to demonstrate that NAADP is a key causal link between glucose sensing and Ca(2+) increases in mouse pancreatic beta cells.

DOI： 10.1038/nchembio.150

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

An ethyl-labeled phosphatidylcholine hydroperoxide (PC-OOH/Et 2) was synthesized as a molecular probe for naturally occurring PC-OOH 1. Applying the precursor ion scan mode in tandem ESI mass spectrometry at m/z 198, a signal of the PC-OOH/Et 2 alone could be selectively detected even in the presence of a large excess of a complex mixture of phospholipids in the blood. Furthermore, molecular species that formed from PC-OOH/Et 2 by its degradation in the blood were also observed in the same spectrum. Since the molecular probe-and-mass spectrometry-assisted analytical method presented herein requires no separation process by HPLC or TLC and is speedy, requiring less than I h, it. may be useful in lipid analysis.

DOI： 10.1271/bbb.80672

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Novel water-soluble conjugates of 1,2,4,5-tetraoxane bis(quaternary ammonium salts) were synthesized in a relatively stable crystalline form via four steps starting from methyltrioxorhenium-catalyzed endo-peroxidation of ethyl 4-oxocyclohexanecarboxylate with hydrogen peroxide in hexafluoro-2-propanol. The assay for the in vitro toxicity of water-soluble tetraoxanes 5a-5d to malaria parasites indicate that they were inactive against the Plasmodium falciparum FCR-3 strain.

DOI： 10.1271/bbb.80571

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Maltosides of butanol, octanol, and lauryl alcohol were found for the first time to serve as substrates for cyclomaltodextrin glucanotransferase (CGTase), and glycosyl residue was transfered from dextrin to the substrate affording novel maltosides with 3-4 glucose units.

DOI： 10.1271/bbb.80295

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Products possessing a levulinyl group were selectively isolated from reaction Mixtures using a new resin-capture method and a polymer-supported aminooxy group. Successive treatment with NaOH in MeOH readily liberated purified products from the resins. Applications of this method to oligosaccharide syntheses are described.

DOI： 10.1246/cl.2008.1030

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We synthesized all of the monomethoxycoumarins, 5-alkoxycoumarins and their derivatives, and investigated their nematicidal activity against the phytopathogenic nematode, Bursaphelenchus xylophilus. Among the compounds, 5-ethoxycoumarin showed the highest nematicidal activity. Furthermore, 5-ethoxycoumarin was comparatively harmless against both the brine shrimps, Artemia salina, and the Japanese killifish, Oryzias latipes. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2008.08.102

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VERLAG Z NATURFORSCH  

Under the bioassay-guided method, two diterpenes, 3-O-(2",3"-dimethylbutanoyl)-13-O-dodecanoylingenol (1) and 3-O-(2",3"-dimethylbutanoyl)-13-O-decanoylingenol (2) isolated from Euphorbia kansui, showed a pronounced antinematodal activity against the nematode Bursaphelenchus xylophilus at the same minimum effective dose (MED) of 5 mu g per cotton ball and still displayed antinematodal activity at a dose of 2.5 mu g per cotton ball. Compounds 3-6 were obtained, and the structure of the new compound 6 was elucidated based on 1D- and 2D-NMR analyses and physicochemical data. Preliminary structure-biological activity relationships of ingenane-type compounds were deduced.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VERLAG Z NATURFORSCH  

Five ingenane compounds, 1-5, kansuinins A and B, isolated from Euphorbia kansui, and their derivatives 7 and 9 were tested for termiticidal activity against the Japanese termite, Reticulitermes speratus. At 72 hours after treatment, the ingenane compounds 1 to 5 caused 100% mortality in R. speratus at 50, 25 and 12.5 mu g/disk, respectively, except for compound 1, which gave a mortality rate of (93.06 +/- 5.56)% at 12.5 mu g/disk. At 36, 48 and 60 hours after treatment, compounds I to 5 showed more termiticidal activity than kansuinins A and B and their derivatives. The kansuinins showed no or only slight activity against termites in the filter paper bioassay under the conditions tested compared with a solvent control.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VERLAG Z NATURFORSCH  

By using a new bioassay-guided method, 2-hydroxy-4-methoxybenzaldehyde isolated from the root bark of Periploca sepium, a traditional Chinese medicine, showed repellent activity against the olive weevil (Dyscerus perforatus) at 62.5, 125, 250 and 500 mu g/disc, respectively. In addition, it also exhibited antinematodal activity against Bursaphelenchus xylophilus at a minimum effective dose of 200 mu g/ball. The three related compounds obtained were also evaluated for the above-mentioned bioactivities.

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Three compounds, 20-O-acetyl-[3-O-(2'E,4'Z)-deca-dienoyl]-ingenol (1), 20-O-acetyl-[5-O-(2'E,4'Z)-decadienoyl]-ingenol (2) and 3-O-(2'E,4'Z)-decadienoylingenol (3), were isolated from Euphorbia kansui under the bioassay-guided method. Each compound showed the same antinematodal activity against the nematode, Bursaphelenchus xylophilus, at a minimum effective dose (MED) of 5 mu g/cotton ball.

DOI： 10.1271/bbb.60677

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Novel fatty acyl and phospholipid derivatives of pyrrole polyamide were synthesized. Their cytotoxicity against a cancer cell line of MT-4 cells and those infected by human immunodeficiency virus (HIV) was examined. Although no anti-HIV activity was found, their cytotoxicitty against the cancer cells was significantly enhanced by introducing a lipophilic group into the pyrrole polyamide.

DOI： 10.1271/bbb.60650

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Sucrose monolauroyl esters were found to serve as substrates for cyclodextrin glucanotransferase (CGTase)-catalyzed transglucosidation reactions, affording new sucrose esters that have an additional 1-3 glucose residues on the pyranose ring of the sucrose moiety in the ester.

DOI： 10.1271/bbb.60646

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Other Link： http://ousar.lib.okayama-u.ac.jp/34238

Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Derivatives of quinine with fatty acids including polyunsaturated fatty acids were prepared. They showed moderate antimalarial activity as compared with quinine itself using Plasmodium falciparum. The activities were not dependent on whether the fatty acyl group was saturated or unsaturated. On the other hand, the derivatives showed significantly higher cytotoxicity against a mammary tumor cell line FM3A than quinine itself. Calculating from these data, an acetyl derivative of quinine with the shortest acyl group was found to give the highest selectivity.

DOI： 10.1271/bbb.69.2250

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

New reductive benzylation of hydroxy functions was effected by using the combination of benzaldehyde, TMSCl, and Et3SiH. TMSCl first reacts with alcohols to form HCl, which is probably the ultimate catalyst for this reaction system. TMSCl can also trap water and thus effectively promote dehydration reactions when more than stoichiometric amount of TMSCl is used. Although excess TMSCl was required for the foregoing reactions, TMSCl could be readily removed by simple evaporation.

DOI： 10.1246/cl.2005.594

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

This paper describes the efficient synthesis of monosaccharides having (mercaptomethyl)diacetylene using Novabiochem(TM) thiol 2-chlorotrityl resin. Coupling of an acetylene-terminated monosaccharide with the propargyl group that is attached to the solid-support afforded diacetylene-linked monosaccharide. The desired thiol compounds were obtained by cleavage of the chlorotrityl group in good yields. Preparation of the gold nano-particles having the monosaccharides via gold-thiol reaction is briefly discussed.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

Two new alkyne-type linkers having alkynylmethyloxy moieties were elaborated for solid-phase synthesis of oligosaccharides. A propargyl glycoside-type linker between a sugar residue and a solid support was formed by the Sonogashira reaction of a propargyl glycoside with polymer-supported iodobenzene. A propargyl ester-type linker was also constructed by the same reaction of a 4-(proparygy1oxycarbonyl)benzyl glycoside with the latter. Both linkers are stable against acids such as TFA but can be readily cleaved with this acid after conversion to the corresponding alkyne-cobalt complex by treatment with Co-2(CO)(8). The latter ester linker is generally advantageous in that mild cleavage liberates a product as its carboxybenzyl glycoside which is readily purified. The Sonogashira reaction was found to proceed only at spatially reactive sites on the solid support where the reagent accesses readily, so that the subsequent reactions including glycosylation on solid phase proceeded smoothly to result in high total yields of the desired oligosaccharides.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Two kinds of 3-nitro-2-pyridyl glycosides were synthesized and evaluated as substrates for continuous spectrophotometric assay for glycosidases. The liberated aglycon, 2-hydroxy-3-nitropyridine, immediately tautomerized to 3-nitro-2(1H)-pyridone, causing an absorption shift of ca. 60 nm even under acidic conditions (pH 3-6). Consequently, the enzymatic hydrolysis of these glycosides was monitored continuously in the acidic to neutral pH range (pH 4-7), the optimum pH for most glycosidases. The absorbance of liberated aglycon increased linearly at 390 nm until 10% consumption of the substrate to enable the initial rate to be determined at once without terminating the reaction. The kinetic parameters for the hydrolysis of 3-nitro-2-pyridyl glycosides were obtained from the slopes of the progress curves and were compared with those obtained from the conventional discontinuous assay using p- and o-nitrophenyl glycosides as substrates. The kinetic parameters indicated that 3-nitro-2-pyridyl glycosides were more activated and specific substrates, but with less affinity to the enzymes than the corresponding nitrophenyl glycosides. Moreover, the absorbance shift by tautomerization should promise further applications to continuous spectrophotometric assays for other enzymes acting under acidic conditions, such as acid proteases and acid phosphatases. (C) 2002 Elsevier Science (USA).

DOI： 10.1006/abio.2001.5558

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Practical Fischer glycosidation was effected at room temperature or 60degreesC by using 5 to 10 equiv. of TMSCl. The anomeric propargyl group formed by this method was found to be a versatile new protecting group, being stable in neat TFA but readily cleaved by treatment with Co-2(CO)(8) and TFA in CH2Cl2 via the formation of an alkyne-Co complex.

DOI： 10.1271/bbb.66.211

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

A new method is described for affinity purification of synthetic compounds based on molecular recognition between bis(2,6-diaminopyridine)amide of isophthalic acid and a barbituric acid derivative. The desired compounds possessing the barbituric acid derivative as a tag were readily isolated from the reaction mixture by the following procedure. After each reaction cycle, the reaction mixture was applied to the polystyrene column possessing bis(2,6- diaminopyridine)amide of isophthalic acid as an artificial receptor. The compound possessing the barbituric acid tag was selectively adsorbed on the column, whereas other impurities without the tag such as excess reagents and byproducts were washed off. Subsequent desorption with CH2Cl2-MeOH (1:1) afforded the desired compound with high purity. This new strategy was applied to the synthesis of a heterocycle, peptides, and oligosaccharides.

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Seven fungi, which are found to reduce ethyl 3-oxobutanoate in high yields, were tested for their reducing ability for ethyl 2-methyl 3-oxobutanoate. We obtained some interesting findings. In particular, Penicillium purpurogenum reduced ethyl 2-methyl 3-oxobutanoate to the corresponding alcohols with the diastereomer (anti/syn) ratio of 93/7 with the enantiomeric excess of anti-(2S, 3S)- and syn-(2S, 3R)-hydroxy esters of 90 and >99ee%, respectively.

DOI： 10.1271/bbb.64.194

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

Chlorella pyrenoidosa Chick reduced ethyl 2-methyl 3-oxobutanoate to the corresponding alcohols with the diastereomer (anti/syn) ratio of 53/47. The enantiomer excesses of anti-(2S, 3S)-and syn-(2S, 3R)-hydroxy esters were 89 and &gt ; 99ee% respectively. C. vulgaris and C. regularis afforded predominantly the syn-isomer, contrary to C. pyrenoidosa. The differences in the activity of reducing ethyl 2-methyl 3-oxobutanoate were observed among three strains of Chlorella. Addition of 2% metal salts slightly increased the chemical yield of the hydroxy ester.

DOI： 10.1271/bbb.63.598

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER IRELAND LTD  

DOI： 10.1016/j.chemphyslip.2009.06.063

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER IRELAND LTD  

DOI： 10.1016/j.chemphyslip.2009.06.031

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER IRELAND LTD  

DOI： 10.1016/j.chemphyslip.2009.06.062

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper, summary (international conference)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper, summary (international conference)  

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J-GLOBAL

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER SCIENCE BV  

Web of Science

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：PESTICIDE SCI SOC JAPAN  

Combinatorial chemistry has become an important tool in both drug discovery and chemical biology and its continued success is dependent, in part, on further advances in solid-phase organic synthesis (SPOS). This paper describes recent findings and a useful method for the synthesis of heterocycle and nitrogen heterocycle compounds. (c) Pesticide Science Society of Japan.

DOI： 10.1584/jpestics.31.1

Web of Science

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CiNii Article

CiNii Books

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Event date： 2022.3.7 - 2022.3.9

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Event date： 2021.11.5

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Event date： 2017.6.8 - 2017.6.9

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Event date： 2015.8.16 - 2015.8.20

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Event date： 2012.9.21 - 2012.9.22

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