Takao Raku
New Energy and Industrial Technology Development Organization
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Publication
Featured researches published by Takao Raku.
Biotechnology Letters | 1999
Masaru Kitagawa; Han Fan; Takao Raku; Shigeo Shibatani; Yoshihiko Maekawa; Yoichi Hiraguri; Ryuichiro Kurane; Yutaka Tokiwa
The protease-catalyzed transesterifications between hexoses and divinyladipate were examined. In dimethylformamide hexoses such as d-glucose, d-mannose, d-galactose and α-methyl d-galactoside were esterified with divinyladipate by alkaline protease from Streptomyces sp. to give corresponding 6-O-vinyl adipoyl sugars. When the denaturing cosolvent, DMSO, was added to the solvent, galactose was selectively esterified at only the C-2 position.
Journal of Biotechnology | 2003
Takao Raku; Masaru Kitagawa; H Shimakawa; Yutaka Tokiwa
To improve trehalose lipophilicity, trehalose was regioselectively esterified with vinyl fatty acid esters in dimethyl formamide by protease from Bacillus subtilis to give 6-O-lauroyltrehalose, 6-O-myristoyltrehalose, 6-O-palmitoyltrehalose, 6-O-stearoyltrehalose, 6-O-oleoyltrehalose and 6-O-linoleoyltrehalose. The influence of structural variation by changing fatty acid substitute was examined by measurement of the surface tension and biodegradability.
Biotechnology Letters | 2003
Takao Raku; Masaru Kitagawa; Hiromi Shimakawa; Yutaka Tokiwa
To enhance water solubility of 10-undecylenic acid, which has anti-fungus, anti-bacterial and anti-virus activity, d-glucose, trehalose and sucrose were regioselectively esterified with vinyl 10-undecylenic acid ester in dimethyl formamide by a commercial protease, Bioprase conc., from Bacillus subtilis. 6-O-(10-Undecylenoyl) d-glucose, 6-O-(10-undecylenoyl) trehalose and 1′-O-(10-undecylenoyl) sucrose were obtained. The influence of structural variation by changing the sugar moiety was analyzed the surface tension and biodegradability.
Biotechnology Letters | 2000
Masaru Kitagawa; Hong Fan; Takao Raku; Ryuichiro Kurane; Yutaka Tokiwa
Transesterification reaction of 0.25 M thymidine with 1 M divinyladipate in dimethylformamide (DMF) was catalyzed by an alkaline protease (5 mg ml−1) from Streptomyces sp. (20 units mg−1 min) at 30 °C for 7 days to give 5′-O-vinyladipoyl thymidine (yield 77%) without formation of any by-products. Poly(vinyl alcohol) containing thymidine branches could be obtained by its free-radical polymerization.
Biotechnology Techniques | 1999
Yutaka Tokiwa; Masaru Kitagawa; Hong Fan; Takao Raku; Yoichi Hiraguri; Shigeo Shibatani; Ryuichiro Kurane
The transesterification of 0.5 M divinyladipate with 0.25 M arabinose in dimethylformamide for 7 days was catalyzed by Streptomyces sp. alkaline protease to give 5-O-vinyladipoyl-d-arabinofuranose at ca. 50% yield. Only enzymatic transesterification of primary hydroxyl group of arabinofuranose proceeded without esterification of arabinopyranose.
Journal of Applied Polymer Science | 2001
Takao Raku; Yutaka Tokiwa
Copolymers of 6-O-vinyladipoyl-D-glucose (VAG) and N-isopropyl acrylamide (NIPAm) were synthesized by radical polymerization. The number-average molecular weights of the copolymers were 3 × 104 ≈ 6 × 104. The observed segment composition of copolymers at the feed molar ratio (VAG 25/NIPAm 75) was VAG 10/NIPAm 90. The polymerization rate of the VAG monomer was slower than that of the NIPAm monomer. The lower critical-solution temperature of copolymers measured with a light-scattering photometer and a differential scanning calorimeter increased with increasing VAG segment composition. The increase in transition temperature was accompanied by a decrease in transition heat.
Biotechnology Letters | 2000
Masaru Kitagawa; Tomoo Tokiwa; Hong Fan; Takao Raku; Yutaka Tokiwa
The transesterification of 1 M divinyladipate with 0.25 M glucose in dimethylformamide (DMF) catalyzed by 5 mg ml−1 alkaline protease (24 units mg−1 min−1) from Streptomyces sp. gave 6-O-vinyladipoyl d-glucose as the main product with yields are between 60 and 90%. The optimum temperature for the reaction was about 50 °C.
Biotechnology Techniques | 1999
Yutaka Tokiwa; Masaru Kitagawa; Hong Fan; Tetsuji Yokochi; Takao Raku; Yoichi Hiraguri; Shigeo Shibatani; Yoshihiko Maekawa; Naoki Kashimura; Ryuichiro Kurane
The transesterification of divinyladipate with adenosine in DMF containing 20% (v/v) DMSO was catalyzed by Streptomyces sp. alkaline protease and esterification occurred exclusively at the 3′-position of hydroxyl group of ribofuranose in adenosine to give 3′-O-vinyladipoyl adenosine without other products.
Biotechnology and Bioprocess Engineering | 2012
Yung-Hun Yang; Takao Raku; Eunjung Song; Sung-Hee Park; Dongwon Yoo; Hyung-Yeon Park; Byung-Gee Kim; Hyung-Ju Kim; Sang Hyun Lee; Hyungsup Kim; Yutaka Tokiwa
To perform the lipase-catalyzed synthesis of L-ascorbic acid derivatives from plant-based compounds such as cinnamic and ferulic acid under mild reaction conditions, the activities of immobilized Candida ntarctica lipase with different cinnamic acid esters and substituted cinnamic acids were compared. As a result, immobilized C. ntarctica lipase was found to prefer vinyl cinnamic acid to other esters such as allyl-, ethyl-, and isobutyl cinnamic acids as well as substituted cinnamic acids such as p-coumaric acid, caffeic acid, ferulic acid, and sinapic acid. Based on these results, large-scale synthesis of 6-O-cinnamyl-L-ascorbic acid ester was performed using immobilized C. ntarctica lipase in dry organic solvent, resulting in 68% yield (493 mg) as confirmed by 13C-NMR.
Biotechnology Letters | 2001
A.A. Vaidya; Takao Raku; Yutaka Tokiwa
N-Isopropylacrylamide (NIPAM) and O-vinyladipoyl uridine were copolymerized in different feed molar ratios ca. 95:5 to 75:25, respectively. The resulting polymers were characterized by gel-permeation chromactography, differential scanning calorimeter and cloud point measurements. The number-average molecular weights of the copolymers were 1.6×104≈3.3×104. The lower critical solution temperature of the copolymer of NIPAM and uridine (95:5) decreases up to 29 °C, compared to that of poly(NIPAM) which remains at 33 °C. These polymers exhibited greater than 80% precipitation of adenosine with 60% efficiency of recovery.
Collaboration
Dive into the Takao Raku's collaboration.
National Institute of Advanced Industrial Science and Technology
View shared research outputsNational Institute of Advanced Industrial Science and Technology
View shared research outputsNational Institute of Advanced Industrial Science and Technology
View shared research outputsNational Institute of Advanced Industrial Science and Technology
View shared research outputsNational Institute of Advanced Industrial Science and Technology
View shared research outputs