Katsuya Koike
Nihon University
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Featured researches published by Katsuya Koike.
Carbohydrate Research | 1987
Masaaki Numata; Mamory Sugimoto; Katsuya Koike; Tomoya Ogawa
Described are total syntheses of O-[sodium (5-acetamido-3,5-dideoxy-D -glycero-alpha-D-galacto-2-nonulopyranosyl)onate]-(2----3)-O -beta-D -galactopyranosyl-(1----1)-(2R,3S,4E)-2-N-tetracosanoylsphingen ine,O-[sodium (5-acetamido-3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosyl+ ++)onate] -(2----3)-O-alpha-D-galactopyranosyl-(1----1)-(2R,3S,4E)-2-N -tetracosanoylsphingenine, O-[sodium (5-acetamido-3,5-dideoxy-D-glycero-beta -D-galacto-2-nonulopyranosyl)onate]-(2----3)-O-beta-D-gal act opyranosyl -(1----1)-(2R,3S,4E)-2-N-tetracosanoylsphingenine, and O-[sodium (5-acetamido-3,5-dideoxy-D-glycero-beta-D-galacto-2-nonulopyranosyl++ +)onate] -(2----3)-O-alpha-D-galactopyranosyl-(1----1)-(2R,3S,4E)-2-N -tetracosanoylsphingenine by using O-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D -galacto-2-nonulopyranosyl)onate]-(2----3)-2,3,4,6-tetra-O-a cetyl-D -galactopyrano-syl trichloroacetimidate and O-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-beta -D-galacto-2-nonulopyranosyl)onate]-(2----3)-2,4,6-tri-O-ace tyl-D-galactopyranosyl trichloroacetimidate as key glycosyl donors, and (2S,3R,4E)-3 -O-benzoyl-2-N-tetracosanoylsphingenine as a key glycosyl acceptor.
Carbohydrate Research | 1987
Katsuya Koike; Mamoru Sugimoto; Susumu Sato; Yukishige Ito; Yoshiaki Nakahara; Tomoya Ogawa
Stereoselective, total synthesis of O-alpha-D-galactopyranosyl-(1----4) -O-beta-D-galactopyranosyl-(1----4)-O-beta-D-glucopyranosyl-(1----1)-N -tetracosanoyl-[2S,3R,4E (and 4Z)]-sphingenine and O-alpha-D -galactopyranosyl-(1----3)-O-beta-D-galactopyranosyl-(1----4)-O-beta-D -glucopyranosyl-(1----1)-N-tetracosanoyl-(2S,3R,4E)-sphin gen ine was achieved by using O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl) -(1----4)-O-(2,3,6-tri-O-acetyl-beta-D-galactopyranosyl)-(1----4)-2,3,6- tri-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate, O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl) -(1----4)-O-(2,3,6-tri-O-acetyl-beta-D-galactopyranosyl)-(1----4)-2,3,6- tri-O-acetyl-alpha (and beta)-D-glucopyranosyl fluoride, and O-(2,3,4,6-tetra-O-acetyl-alpha-D -galactopyranosyl)-(1----3)-O-(2,3,6-tri-O-acetyl-beta-D-galactopyran osyl)-(1----4)-2,3,6-tri-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate.
Carbohydrate Research | 1986
Katsuya Koike; Masaaki Numata; Mamoru Sugimoto; Yoshiaki Nakahara; Tomoya Ogawa
Abstract The synthesis of 4-E- and 4-Z- d -erythro-ceramide was achieved in 10 steps in ∼20–30% overall yield, starting from 1,2:5,6-di-O-isopropylidene-α- d -glucofuranose. E- and Z-5-Deoxy-1,2-O-isopropylidene-5-C-tetradecylidene-α- d -xylofuranose were used as key intermediates.
Glycoconjugate Journal | 1984
Katsuya Koike; Yoshiaki Nakahara; Tomoya Ogawa
Because of its crucial importance as a major consti tuent of biological membranes [2, 3], several synthetic approaches to the optically active ceramide 1, the hydrophobic part of the sphingolipids, have recently been reported [4-7]. As a practical and an efficient route for the synthesis of ceramide 1 based on the concept of a carbohydrate template [8], we describe here an 11-step conversion of 1,2,5,6-di-O-isopropylidene-oz-D-glucofu ranoside 2 into D-erythro-ceramide 1 (see Fig. 1) in an overall yield of about 20% (the yields are not optimised).
Carbohydrate Research | 1986
Mamoru Sugimoto; Masaaki Numata; Katsuya Koike; Yoshiaki Nakahara; Tomoya Ogawa
Synthese de (O-glycosyl N-tetracosanoyl) sphingosines. La partie glycosyle etant soit un tetraholoside, soit un pentaholoside
Carbohydrate Research | 1987
Katsuya Koike; Mamoru Sugimoto; Yoshiaki Nakahara; Tomoya Ogawa
Abstract Total syntheses of both (2S, 3R, 4E)-1-O-β- d -galactopyranosyl-N-(2′R)-2′-hydroxytetracosanoylsphingenine 23 and the (2′S) stereoisomer were performed in an unambiguous way by employing either (2S, 3R, 4E)-N-(2′R)-2′-(tert-butyl-diphenylsilyloxy)tetracosanoylsphingenine or its (2′S) stereoisomer as the key glycosyl acceptors. The synthetic cerebroside 23 was shown to be identical with the natural product through comparison of their 400-MHz, 1H-n.m.r. spectra, thus providing synthetic evidence for the 2′R configuration of the natural cerebroside.
Glycoconjugate Journal | 1985
Katsuya Koike; Mamoru Sugimoto; Yoshiaki Nakahara; Tomoya Ogawa
The cerebrosides were first isolated by Thudicum in 1874 and the structures were established by Carteret al. in 1950 (for review, see [2]). In 1961 Shapiro and Flowers [3] reported the first total synthesis of a cerebroside1 (Fig. 1) which was identified with the natural sample, only through comparison of their i.r. data. In order to confirm the absolute configuration at C-2′ of natural cerebroside1, we describe here an unambiguous synthesis of two stereoisomeric cerebrosides1 and2, and found that the1H-NMR spectra of the synthetic1 (Fig. 2) was completely identical with that of the natural cerebroside reported recently by Dabrowskiet al. [4].In planning the synthetic route, the target structures1 and2 were disconnected at the dotted lines to give three key synthetic intermediates3, 4 and5 or6 (Fig. 1).
Chemistry and Physics of Lipids | 1988
Janusz Dabrowski; Karin Trauner; Katsuya Koike; Tomoya Ogawa
Two-dimensional scalar-correlated (COSY) 1H-NMR spectra of the title compounds, and phase-sensitive COSY spectrum of lactosylceramide, have been fully assigned and some spectral reassignments for related structures suggested. Glycosylation-induced shifts, and shielding by Z- and E-ceramide residues are discussed.
Glycoconjugate Journal | 1987
Katsuya Koike; Masato Mori; Yukishige Ito; Yoshiaki Nakahara; Tomoya Ogawa
The first total synthesis of glycosphingolipids isolated from wheat flour has been achieved in a regio- and stereo-controlled manner.
Journal of Histochemistry and Cytochemistry | 2008
Yuriko Kobayashi; Keiichi Suzuki; Hideaki Kobayashi; Sachiyo Ohashi; Katsuya Koike; Paolo Macchi; Michael A. Kiebler; Kaijiro Anzai
Purα has been implicated in mRNA transport and translation in neurons. We previously reported that Purα is a component of mRNA/protein complexes (Purα-mRNPs) with several other proteins. Among them, we found the C9orf10 (Homo sapiens chromosome 9 open reading frame 10) protein, which was recently characterized as a component of RNA-containing structures. However, C9orf10 itself remains poorly understood. To characterize C9orf10 expression at the protein level, we raised an antibody against C9orf10 and compared the spatial and developmental expressions of this protein and Purα in the mouse brain. C9orf10 was expressed as early as embryo stage 12, whereas Purα was expressed from 5 days after birth. In adults, C9orf10 expression was most prominent in the hippocampus, caudate putamen, cerebral cortex, and cerebellum, unlike the uniform distribution of Purα. C9orf10-positive cells also showed immunoreactivity to Purα. C9orf10 expression was restricted to neurons, judging by the immunoreactivity to neuron-specific nuclear protein or CaM kinase II. These observations suggest an accessory role of C9orf10 for Purα in a limited brain region in addition to other possible functions that have not yet been determined.