The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Ken Izumori - One of the best experts on this subject based on the ideXlab platform.
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preparation of d Gulose from disaccharide lactitol using microbial and chemical methods
Bioscience Biotechnology and Biochemistry, 2013Co-Authors: Kenji Morimoto, Tsuyoshi Shimonishi, Seiki Miyake, Goro Takata, Ken IzumoriAbstract:When an M31 strain of Agrobacterium tumefaciens was grown in a mineral salt medium at 30 °C containing 1.0% lactitol as sole carbon source, a keto-sugar was efficiently accumulated in the supernatant. This oxidation from lactitol to the keto-sugar was caused by M31 cells grown with medium containing a disaccharide unit, including sucrose, lactitol, lactose, maltose, or maltitol, suggesting that the enzyme is inducible. M31 also demonstrated good growth characteristics in Tryptic Soy Broth (TSB) medium containing 1.0% sucrose, and cells grown under these conditions showed strong lactitol transformation activity. The keto-sugar product was reduced by chemical hydrogenation and the resulting product was hydrolyzed to D-Gulose, D-galactose, and D-sorbitol by acid hydrolysis, revealing that the reduced products are lactitol and D-gulosyl-(β-1,4)-D-sorbitol. Taken together, these results indicate that M31 can convert lactitol to 3-ketolactitol and thus provide access to the rare sugar D-Gulose.
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preparation of l talose and d Gulose from l tagatose and d sorbose respectively using immobilized l rhamnose isomerase
Journal of Bioscience and Bioengineering, 1999Co-Authors: Shakhawat Hossain Bhuiyan, Yoshiyuki Itami, Goro Takada, Ken IzumoriAbstract:l-Rhamnose isomerase of Pseudomonas sp. LL172 immobilized on BCW 2603 Chitopearl beads was used to produce l-talose and d-Gulose. At equilibrium, the production yields of l-talose and d-Gulose were determined to be 12 and 10% from l-tagatose and d-sorbose, respectively. The crystallized products were confirmed by HPLC, IR and NMR spectra, and optical rotation measurement analyses.
Maurizio Botta - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective protecting group free synthesis of D,L-Gulose ethyl glycoside via multicomponent enyne cross metathesis--hetero Diels-Alder reaction.
Carbohydrate research, 2009Co-Authors: Daniele Castagnolo, Lorenzo Botta, Maurizio BottaAbstract:An efficient and stereoselective synthesis of d,l-Gulose was described. The key step of the synthetic route is represented by a multicomponent enyne cross metathesis—hetero Diels–Alder reaction which allows the formation of the pyran ring from cheap and commercially available substrates in a single synthetic step. The synthesis of d,l-Gulose was accomplished without the use of protecting groups making this approach highly desirable also in terms of atom economy.
Osamu Tamura - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective vinylogous Mannich reaction of 2-trimethylsilyloxyfuran with N-gulosyl nitrones
Organic & biomolecular chemistry, 2011Co-Authors: Osamu Tamura, Naka Mita, Masanori Sakamoto, Kodai Takeda, Iwao Okamoto, Nobuyoshi Morita, Hiroyuki IshibashiAbstract:Stereoselective vinylogous Mannich reaction of 2-trimethylsilyloxyfuran with L-Gulose-derived chiral nitrones in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate was investigated. The selectivity was strongly influenced by the bulkiness of the C-substituent of the nitrone: for example, C-benzyloxymethyl nitrone afforded four stereoisomers, whereas bulky C-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]nitrone gave a single stereoisomer. The latter product was elaborated to afford key synthetic intermediates for polyoxin C and dysiherbaine.
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Synthesis of (3′R,5′S)-3′-hydroxycotinine using 1,3-dipolar cycloaddition of a nitrone
Tetrahedron, 2004Co-Authors: Osamu Tamura, Ayano Kanoh, Masayuki Yamashita, Hiroyuki IshibashiAbstract:Abstract To synthesize (3′R,5′S)-3′-hydroxycotinine [ (+)-1 ], the main metabolite of nicotine ( 2 ), cycloaddition of C-(3-pyridyl)nitrones 3a , 3c , and 15 with (2R)- and (2S)-N-(acryloyl)bornane-10,2-sultam [(2R)- and (2S)-8 ] was examined. Among them, l -Gulose-derived nitrone 15 underwent stereoselective cycloaddition with (2S)-8 to afford cycloadduct 16 , which was elaborated to (+)-1 .
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synthesis of 3 r 5 s 3 hydroxycotinine using 1 3 dipolar cycloaddition of a nitrone
Tetrahedron, 2004Co-Authors: Osamu Tamura, Ayano Kanoh, Masayuki Yamashita, Hiroyuki IshibashiAbstract:Abstract To synthesize (3′R,5′S)-3′-hydroxycotinine [ (+)-1 ], the main metabolite of nicotine ( 2 ), cycloaddition of C-(3-pyridyl)nitrones 3a , 3c , and 15 with (2R)- and (2S)-N-(acryloyl)bornane-10,2-sultam [(2R)- and (2S)-8 ] was examined. Among them, l -Gulose-derived nitrone 15 underwent stereoselective cycloaddition with (2S)-8 to afford cycloadduct 16 , which was elaborated to (+)-1 .
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intramolecular cycloaddition of α allyloxycarbonylnitrone bearing a chiral sugar auxiliary a short step synthesis of the n terminal amino acid component of nikkomycin bz
Tetrahedron Letters, 1997Co-Authors: Osamu Tamura, Naka Mita, Noriko Kusaka, Hirohide Suzuki, Masanori SakamotoAbstract:Abstract Heating 2,3:5,6- O -dicyclohexylidene-L-Gulose oxime with methyl glyoxylate hemiacetal followed by treatment of the resulting mixture with allyl alcohols in the presence of catalytic amounts of titanium tetrachloride and molecular sieves 4A caused tandem nitrone formation, transesterification, E , Z -isomerization and diastereofacial selective intramolecular cycloaddition to provide stereocontrolled polycyclic compounds in one step. This method could be applied efficiently to synthesis of the N -terminal amino acid component of nikkomycin Bz.
Masanori Sakamoto - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective vinylogous Mannich reaction of 2-trimethylsilyloxyfuran with N-gulosyl nitrones
Organic & biomolecular chemistry, 2011Co-Authors: Osamu Tamura, Naka Mita, Masanori Sakamoto, Kodai Takeda, Iwao Okamoto, Nobuyoshi Morita, Hiroyuki IshibashiAbstract:Stereoselective vinylogous Mannich reaction of 2-trimethylsilyloxyfuran with L-Gulose-derived chiral nitrones in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate was investigated. The selectivity was strongly influenced by the bulkiness of the C-substituent of the nitrone: for example, C-benzyloxymethyl nitrone afforded four stereoisomers, whereas bulky C-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]nitrone gave a single stereoisomer. The latter product was elaborated to afford key synthetic intermediates for polyoxin C and dysiherbaine.
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intramolecular cycloaddition of α allyloxycarbonylnitrone bearing a chiral sugar auxiliary a short step synthesis of the n terminal amino acid component of nikkomycin bz
Tetrahedron Letters, 1997Co-Authors: Osamu Tamura, Naka Mita, Noriko Kusaka, Hirohide Suzuki, Masanori SakamotoAbstract:Abstract Heating 2,3:5,6- O -dicyclohexylidene-L-Gulose oxime with methyl glyoxylate hemiacetal followed by treatment of the resulting mixture with allyl alcohols in the presence of catalytic amounts of titanium tetrachloride and molecular sieves 4A caused tandem nitrone formation, transesterification, E , Z -isomerization and diastereofacial selective intramolecular cycloaddition to provide stereocontrolled polycyclic compounds in one step. This method could be applied efficiently to synthesis of the N -terminal amino acid component of nikkomycin Bz.
Bo Jiang - One of the best experts on this subject based on the ideXlab platform.
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L-Rhamnose isomerase and its use for biotechnological production of rare sugars.
Applied microbiology and biotechnology, 2016Co-Authors: Wenli Zhang, Tao Zhang, Bo JiangAbstract:L-Rhamnose isomerase (L-RI, EC 5.3.1.14), catalyzing the isomerization between L-rhamnose and L-rhamnulose, plays an important role in microbial L-rhamnose metabolism and thus occurs in a wide range of microorganisms. It attracts more and more attention because of its broad substrate specificity and its great potential in enzymatic production of various rare sugars. In this article, the enzymatic properties of various reported L-RIs were compared in detail, and their applications in the production of L-rhamnulose and various rare sugars including D-allose, D-Gulose, L-lyxose, L-mannose, L-talose, and L-galactose were also reviewed.