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51.
Akira Tokuda Toshio Ariga Yukihiro Isogai Shiro Komba Makoto Kiso Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(4-5):535-546
Abstract The mouse monoclonal anti-human HNK-1 antibody (also variously known as L2, Leu-7, CD57, VC1.1), monoclonal anti-sulfoglucuronosyl glycosphingolipids (SGGLs) antibody (mAb NGR50), and human sera from patients with demyelinating neuropathy and IgM paraproteinemia, are known to react with not only SGGLs, including sulfoglucuronosyl paragloboside (SGPG) and sulfoglucuronosyl lactosaminyl paragloboside (SGLPG), but also glycoproteins, such as myelin-associated glycoprotein (MAG), PO, PMP22, and certain adhesion molecules. These antigens are known to possess the so-called HNK-1 epitope (3-sulfoglucuronic acid, SGA) moiety. To further define the precise structural requirement of this carbohydrate epitope, we chemically synthesized 14 SGGLs, and their nonsulfated derivatives with defined carbohydrate chain lengths and aglycone structures. The various aglycones include ceramide, 2-(tetradecyl)hexadecyl (B30), and 2-(trimethylsilyl)ethyl (SE). These synthetic SGGLs were tested for their immunoreactivity with the above antibodies by high-performance thin-layer chromatography (HPTLC)-immunoblotting and ELISA. The anti-HNK-1 antibody (VC1.1) reacted with SGGL analogues containing a minimum of two sugars (SGA-Gal-Cer), but not with non-sulfated derivatives of SGGLs nor with SGGLs having a modified ceramide structure. mAb NGR50, on the other hand, reacted with only SGPG and SGLPG. A human patient serum (LT) reacted with all synthetic SGGLs except those with an SE aglycone structure. On the other hand, another human patient serum (YT). like the anti-HNK-1 antibody, VC1.1, reacted with SGPG, SGLPG, and SGGL analogues containing a minimum of two sugars (SGA-Gal-Cer). All antibodies reacted more strongly with synthetic SGGLs with longer carbohydrate chains. These results indicate that anti-SGGL antibodies recognize a minimum of two sugars bearing the following structure (3-sulfoglucuronosyl β 1-3 galactosyl, SGA-Gal-) and that the aglycone (“ceramide”) structure appears to play an important role for antibody-antigen interaction. 相似文献
52.
Naotake Konno Naoto Habu Natsuko Iihashi Akira Isogai 《Cellulose (London, England)》2008,15(3):453-463
A bacterial strain, Brevundimonas sp. SH203, has an ability to degrade cellouronate, β-(1→4)-linked polyglucuronic acid sodium salt, which is artificially
prepared from regenerated cellulose by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation. In a previous
paper, an endo-type cellouronate lyase (CUL-I) has been isolated from the strain. In this paper, we purified another cellouronate
lyase, CUL-II, from cell-free extracts of Brevundimonas sp. SH203. CUL-II was a monomeric protein with a molecular mass of 56 kDa by size exclusion chromatography and 62 kDa by
sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and most active at pH 7.5. CUL-II formed monomers in a small quantity
from cellouronate without forming any intermediate oligomers, whereas it degraded C4′–C5′ unsaturated cellouronate dimer more
easily. Thus, CUL-II behaves as an exo-type lyase in degradation of cellouronate. When CUL-I and CUL-II were simultaneously
treated to cellouronate, it was degraded to monomers more efficiently than treatment with one enzyme alone, CUL-I or CUL-II.
Hence, cellouronate is synergistically degraded to monomers by Brevundimonas sp. SH203 by endo- and exo-type lyases, CUL-I and CUL-II, respectively. 相似文献
53.
A wood cellulose was oxidized with catalytic amounts of 2-azaadamantane N-oxyl (AZADO) or 1-methyl-AZADO, in an NaBr/NaClO system, in water at pH 10. The oxidation efficiency, carboxylate/aldehyde contents, and degree of polymerization (DPv) of the oxidized celluloses thus obtained were evaluated in terms of the amount of AZADO or 1-methyl-AZADO catalyst added, in comparison with those prepared using the TEMPO/NaBr/NaClO system. When the AZADO/NaBr/NaClO and 1-methyl-AZADO/NaBr/NaClO oxidation systems were applied to wood cellulose using the same molar amount of TEMPO, the oxidation time needed for the preparation of oxidized celluloses with carboxylate contents of 1.2–1.3 mmol/g was reduced from ≈80 to 10–15 min. Moreover, the molar amounts of AZADO and 1-methyl-AZADO that had to be added for the preparation of oxidized celluloses with carboxylate contents of 1.2–1.3 mmol/g were reduced to 1/32 and 1/16 of the amount of TEMPO added, respectively. The DPv values for the AZADO- and 1-methyl-AZADO-oxidized celluloses after NaBH4 treatment were in the range of 600–800. This indicated that not only C6-carboxylate groups but also C2/C3 ketones were formed to some extent on the crystalline cellulose microfibril surfaces during the AZADO- and 1-methyl-AZADO-mediated oxidation. When the AZADO-oxidized wood cellulose, which had a carboxylate content of 1.2 mmol/g, was mechanically disintegrated in water, an almost transparent dispersion consisting of individually nano-dispersed oxidized cellulose nanofibrils was obtained, with a nanofibrillation yield of 89 %. 相似文献
54.
Akira Hasegawa Hideki Ishida Yukihiro Isogai Hideharu Ishida Makoto Kiso 《Journal of carbohydrate chemistry》2013,32(8):1217-1222
Abstract As more and more biological functions1-10 of gangliosides are being revealed, their facile, stereocontrolled synthesis is strongly required. We have developed11-l4 an α-stereoselective glycosylation of sialic acids, α-sialyl-(2→8)-sialic acid and α-sialyl-(2→8)-α-sialyl-(2→8)-sialic acid, by using their 2-thioglycosides as the glycosyl donor and suitably protected acceptors, and dimethyl(methy1thio)sulfonium triflate (DMTST) or N-iodosuccinimide (NIS)-trifluoromethanesufonic acid (or TMS triflate) as the glycosyl promoter in acetonitrile. In this way, we have synthesized a variety of gangliosides15 and their analogs.16 Previously,13 we synthesized Ganglioside GD3 containing α-sialyl-(2-8)-sialic acid residue in the molecule, in connection with a novel approach for systematic synthesis of polysialo-glycoconjugates. As a part of our continuing studies on the synthesis and elucidation of the functions of gangliosides, we describe here a facile, stereocontrolled, total synthesis of ganglioside GD2. Ganglioside GD2, which was first isolated from human brain by R. Kuhn et al.,17 is well known as a human melanoma associated antigen.18 相似文献
55.
Yukihiro Isogai Tomoko Kawase Hideharu Ishida Makoto Kiso Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(8):1001-1023
ABSTRACT 3-O-Sulfo glucuronyl paragloboside derivatives (pentasaccharides) have been synthesized. The important intermediate designed for a facile sulfation in the last step and effective, stereocontrolled glycosidation, methyl (4-O-acetyl-2-O-benzoyl-3-O-levulinoyl-α-D-glucopyranosyl trichloroacetimidate)uronate (8) was prepared from methyl [2-(trimethylsilyl)ethyl β-D-glucopyranosid]uronate (3) via selective 4-O-acetylation, 2-O-benzoylation, 3-O-levulinoylation, removal of the 2-(trimethylsilyl)ethyl group and imidate formation. The glycosylation of 8 with 2-(trimethylsilyl)ethyl 2,4,6-tri-O-benzyl-β-D-galactopyranoside (9) using trimethylsilyl trifluoromethanesulfonate gave 2-(trimethylsilyl)ethyl O-(methyl 4-O-acetyl-2-O-benzoyl-3-O-levulinoyl-β-D-glucopyranosyluronate)-(1→3)-2,4,6-tri-O-benzyl-β-D-galactopyranoside (10), which was transformed via removal of the benzyl group, benzoylation, removal of the 2-(trimethylsilyl)ethyl group and imidate formation into the disaccharide donor 13. On the other hand, 2-(trimethylsilyl)ethyl O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranosyl)-(1→3)-O-(2,4,6-tri-O-benzyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (20) as the acceptor was prepared from 2-(trimethylsilyl)ethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranoside (14) via O-acetylation, removal of the 2-(trimethylsilyl)ethyl group, imidate formation, coupling with 2-(trimethylsilyl)ethyl O-(2,4,6-tri-O-benzyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (18), removal of the O-acetyl and N-phthaloyl group followed by N-acetylation. Condensation of 13 with 20 using trimethylsilyl trifluoromethanesulfonate afforded the desired pentasaccharide 21, which was transformed by removal of the benzyl group, O-acetylation, removal of the 2-(trimethylsilyl)ethyl group and imidate formation into the pentasaccharide donor 24. Glycosylation of (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (25) with 24 gave the desired β-glycoside 26, which was transformed into the four target compounds, via reduction of the azido group, coupling with octadecanoic acid or tetracosanoic acid, selective removal of the levulinoyl group, O-sulfation, hydrolysis of the methyl ester group and O-deacylation. 相似文献
56.
G. T. Cook E. M. Scott A. B. MacKenzie F. H. Naysmith K. Isogai P. J. Kershaw R. Anderson P. Naysmith 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(2):239-247
Prior to 1984, the reported marine 14C discharges from Sellafield were estimates: 0.2 TBq per annum from 1952 to 1969 and 1 TBq per annum until 1984 when measurements
commenced. The relationship between the net excess 14C activity in annually collected Nori (Porphyra umbilicalis) seaweed samples and the annual discharges (estimated and measured) implies that the discharges were not as constant as the
estimates. Based on the relationship between post-1984 measured discharges and the excess 14C in the seaweed, two simple empirical models were used to re-calculate the discharges between 1967 and 1984. Gamma-spectrometry
measurements on the seaweed also indicate that Porphyra is a sensitive indicator of changes in discharge of other radionuclides, brought about by the introduction of new waste clean-up
technologies within Sellafield.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
57.
Shuji Fujisawa Yusuke Okita Tsuguyuki Saito Eiji Togawa Akira Isogai 《Cellulose (London, England)》2011,18(5):1191-1199
A method for conversion of carboxyl groups present on the surface of TEMPO-oxidized cellulose nanofibrils to N-acylureas using carbodiimide was developed. A TEMPO-oxidized cellulose nanofibril with free carboxyl groups (TOCN–COOH) dispersed
in N,N-dimethylformamide (DMF) is prepared from a bleached kraft pulp, and then the TOCN–COOH is reacted with either N,N′-diisopropylcarbodiimide (DIC) or N,N′-dicyclohexylcarbodiimide (DCC) under apparently homogeneous conditions. FT-IR and solid-state 13C NMR analyses showed that the reaction products contained N-acylurea groups, and yields were >80%. Conversion ratios of carboxyl groups to N-acylureas are approximately 80 and 60%, when DIC and DCC, respectively, of 5 mol per mole of carboxyl groups are used as
the reagents. X-ray diffraction analysis demonstrated that neither crystallinity nor crystal width of the original wood cellulose
I structure was changed by the N-acylurea formation. The isolated and never-dried TOCN-N-acylureas are nano-dispersed in DMF but not in i-PrOH or dioxane. Pellets of the TOCN-N-acylureas had water-contact angles of >70°. 相似文献
58.
Masayuki Hirota Naoyuki Tamura Tsuguyuki Saito Akira Isogai 《Cellulose (London, England)》2010,17(2):279-288
Mercerized wood cellulose was oxidized by 4-acetamide-TEMPO/NaClO/NaClO2 system at 60 °C and pH 4.8 for 1–5 days. Mostly individual nanocrystals 4–7 nm in width and 100–200 nm in length were obtained
by ultrasonication of the oxidized product in water. The nanocrystals had the cellulose II structure, and carboxylate contents
of 2.0–2.4 mmol/g, indicating that these carboxylate groups were selectively formed on the cellulose II crystallite surfaces
in mercerized cellulose. Moreover, the original wood cellulose and mercerized cellulose were acid-hydrolyzed, and then subjected
to the TEMPO-mediated oxidation under the same conditions at pH 4.8 to prepare reference samples. TEM images, light transmittance
and rheological properties of water dispersions showed that the nanocrystals prepared from mercerized cellulose by the TEMPO
oxidation and sonication in water had the highest dispersibility of individual nanocrystals with less amounts of bundles in
water, resulting from the highest carboxylate contents. 相似文献
59.
The surface of a poly(l-lactic acid) (PLLA) film was modified with poly(acrylic acid) (PAA) by plasma-initiated polymerization to increase the interaction between PLLA and cellulose single nanofibres (CSNF). The surface wettability of the PAA grafted PLLA film (PLLA-PAA film) was investigated by contact angle measurements. Modification of the PLLA film with PAA decreased the contact angle from 61° to 50°. The surface morphologies of the PLLA film, PLLA-PAA film and CSNF-coated PLLA-PAA film were studied by atomic force microscopy. The interaction between the CSNF and PLLA layers was strengthened by incorporation of a PAA layer onto the PLLA films and it is higher than 2N as proved by a peeling test. This is probably because the carboxyl groups of PAA form hydrogen bonds with the hydroxyl groups of CSNF. 相似文献
60.
Eiichi Isogai 《Annals of the Institute of Statistical Mathematics》1986,38(1):69-83
Summary Letm
n
(x) be the recursive kernel estimator of the multiple regression functionm(x)=E[Y|X=x]. For given α (0<α<1) andd>0 we define a certain class of stopping timesN=N(α,d, x) and takeI
N,d
(x)=[m
N
(x)−d, m
N
(x)+d] as a 2d-width confidence interval form(x) at a given pointx. In this paper it is shown that the probability P{m(x)∈I
N,d
(x)} converges to α asd tends to zero. 相似文献