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PubMed1983

Structural differences of heparan sulfates according to the tissue and species of origin.

Some structural features of thirteen heparan sulfates isolated from different mammalian tissues and species are reported. Two N-acetylated disaccharides, one of then O-sulfated and two N-sulfated disaccharides, one of then 6-sulfated are formed from these compounds by the combined action of heparitinases I and II from Flavobacterium heparinum. The relative proportions of the four disaccharide units vary quite significantly among the thirteen heparan sulfates indicating that the structure of these polymers are tissue and species specific. Based on the frequency of appearance of each one of the disaccharides it was calculated that 10(36) types of heparan sulfates might theoretically be found. The possible role of these polyanions in cell-cell recognition is discussed in view of the present findings.

Animals↗
PubMed1984

Synthesis of 2-acetamido-2-deoxy-6-O-beta-D-galactopyranosyl-D-galactopyranose and o-nitrophenyl 2-acetamido-2-deoxy-6-O-beta-D-galactopyranosyl -alpha-D-galactopyranoside.

Acetalation of o-nitrophenyl 2-acetamido-2-deoxy-alpha-D-galactopyranoside with p-methoxybenzaldehyde-zinc chloride complex afforded the 4,6-O-(p-methoxybenzylidene) derivative (1). Acetylation of 1 with pyridine-acetic anhydride gave the crystalline monoacetate (2), the acetal group of which was cleaved by brief treatment with hot, 80% aqueous acetic acid to furnish the diol (3). The 1H-n.m.r. spectra of both 2 and 3 supported their overall structures. Glycosylation of 3 with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (5) in 1:1 nitromethane-benzene, in the presence of mercuric cyanide, afforded the disaccharide derivative (6). O-Deacetylation of 6 in methanolic sodium methoxide gave the title disaccharide (8). A similar glycosylation of benzyl 2-acetamido-3-O-acetyl-2-deoxy-alpha-D-galactopyranoside with bromide 5, followed by O-deacetylation of the resulting intermediate, produced disaccharide 9. The structures of 8 and 9 were confirmed by 13C-n.m.r. spectroscopy. Hydrogenolysis of the benzyl aglycon of 9 gave the free disaccharide 2-acetamido-2-deoxy-6-O-beta-D-galactopyranosyl-D-galactopyranose (13). The 13C-n.m.r. spectrum of 13 is recorded, and discussed in conjunction with those of the beta-(1----3)- and the beta-(1----4)-linked isomers.

Disaccharides↗
PubMed1992

Conformational analysis of the anomeric forms of kojibiose, nigerose, and maltose using MM3.

Energy surfaces were computed for relative orientations of the relaxed pyranosyl rings of the two anomeric forms of kojibiose, nigerose, and maltose, the (1----2)-alpha, (1----3)-alpha, and (1----4)-alpha-linked D-glucosyl disaccharides, respectively. Twenty-four combinations of starting conformations of the rotatable side-groups were considered for each disaccharide. Optimized structures were calculated using MM3 on a 20 degree grid spacing of the torsional angles about the glycosidic bonds. The energy surfaces of the six disaccharides were similar in many respects but differed in detail within the low-energy regions. The maps also illustrate the importance of the exo-anomeric effect and linkage type in determining the conformational flexibility of disaccharides. Torsional conformations of known crystal structures of maltosyl-containing molecules lie in a lower MM3 energy range than previously reported.

Carbohydrate Conformation↗
PubMed1995

Synthesis of a thio analogue of n-propyl kojibioside, a potential glucosidase inhibitor.

The disaccharide alpha-D-Glc p-(1-S-2)-beta-D-Glc p-(1-OPr) 1, a thio analogue of alpha-D-Glc p-(1 --> 2)-alpha-D-Glc p-(1-OPr)(n-propyl kojibioside) in which the inter-glycosidic oxygen atom is replaced by sulfur, has been synthesized for evaluation as a potential glucosidase inhibitor. Glycosylation of the 2-thiol glucopyranosyl acceptor 4 with the trichloroacetimidate of 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranose 5 gave the alpha-linked disaccharide 6 stereoselectively. Deprotection was performed by hydrogenolysis in the presence of Pd/C to give 1 as the beta-n-propyl glycoside. Glycosylation of the thiol 4 with the trichloroacetimidate of 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranose 8 gave a 1:2.3 mixture if the alpha and beta disaccharides (9 and 10); evidence is presented for the occurrence of the orthoester 11, as an intermediate in the formation of the beta-disaccharide.

Carbohydrate Sequence↗
PubMed1987

The application of chondro-2-sulfatase for identification of the products generated from chondroitin sulfate isomers by high-performance liquid chromatography.

A specific chondroitin sulfate-lyase, chondro-2-sulfatase, was first used for identification of the unsaturated disaccharide constituents (delta Di-S) generated from variously sulfated chondroitin sulfate and dermatan sulfate isomers by a high-performance liquid chromatographic (HPLC) method. delta Di-S generated from oversulfated chondroitin sulfate and dermatan sulfate isomers following digestion with chondroitinases were further digested by the chondro-2-sulfatase, which led to the release of one sulfate from a specific 2-position of the uronic acid residue, as judged with the new HPLC system using a resin made from a sulfonized styrene-divinylbenzene copolymer. It was also found that the chondro-2-sulfatase digests not only delta Di-S with the structure of D-uronic acid 2 sulfate 1-3-N-acetyl-D-galactosamine but also other sulfated delta Di-S with partially the same constituents, i.e., unsaturated di-sulfated disaccharide B, unsaturated di-sulfated disaccharide D or G, and unsaturated tri-sulfated disaccharide.

Chondroitin↗
PubMed2004

The significant effect of the carbohydrate structures on the DNA photocleavage of the quinoxaline-carbohydrate hybrids.

The novel DNA interactive quinoxaline-carbohydrate hybrids possessing disaccharides as the carbohydrate moieties were designed and synthesized, and their DNA photocleaving abilities were evaluated in order to examine the effect of the disaccharide structures. The configurations of the glycosidic bonds in the disaccharide strongly affected the DNA photocleaving ability, and two beta-glycosidic bond linkages were very effective for the DNA photocleavage. Furthermore, the quinoxaline-disaccharide hybrids exhibited selective cytotoxicity against cancer cells with photoirradiation.

Antineoplastic Agents↗
PubMed2006

The glass transition temperatures of sugar mixtures.

We measured the glass transition temperatures of mono-, di-, and trisaccharide mixtures using differential scanning calorimeter (DSC) and analyzed these temperatures using the Gordon-Taylor equation. We found that the glass transition temperatures of monosaccharide-monosaccharide and disaccharide-disaccharide mixtures could be described by the conventional Gordon-Taylor equation. However, the glass transition temperatures of monosaccharide-disaccharide and monosaccharide-trisaccharide mixtures deviated from the conventional Gordon-Taylor equation and the amount of deviation in the monosaccharide-trisaccharide mixtures was larger than those in the monosaccharide-disaccharide mixtures. From these results, we conclude that the size and shape of the sugars play an important role in the glass transition temperature of the mixtures.

Disaccharides↗
PubMed2006

Incorporation of a S-glycosidic linkage into a glyconucleoside changes the conformational preference of both furanose sugars.

A glyconucleoside containing a thioglycoside linkage, namely 1-(3-S-beta-D-ribofuranosyl-2,3-dideoxy-3-thio-beta-D-ribofuranosyl)-thymine, has been prepared through condensation of a suitably protected derivative of 3'-thiothymidine with an activated ribose sugar. NMR has been used to study the conformation of the S-disaccharide and the unmodified O-disaccharide. A full pseudorotational analysis showed that for the S-disaccharide, the ribose and deoxy ribose sugars have a preference for the south and north pucker, respectively; which is the reverse of what is seen for the O-disaccharide.

Carbohydrate Conformation↗
PubMed2005

Quantitative analysis of chondroitin sulfate in raw materials, ophthalmic solutions, soft capsules and liquid preparations.

We performed the quantitative analysis of chondroitin sulfate (CS) obtained from raw materials and various pharmaceutical preparations. To quantify CS content in raw materials and in an ophthalmic solution, each test sample and the authentic CS were first digested by chondroitinase ABC. The CS disaccharides produced were analyzed by strong anion-exchange high-performance liquid chromatography (SAX-HPLC) and CS content was quantified by calculating the total peak areas of the disaccharides derived from a CS calibration curve. In the case of soft capsules, CS was first extracted with hexane followed by phenol-chloroform to remove oil and protein ingredients. The extracted CS samples were depolymerized by chondroitinase ABC and CS content was determined. Quantitative analysis of the disaccharides derived from raw materials and an ophthalmic solution showed the CS contents (%) were 39.5+/-0.1 to 105.6+/-0.1 and 103.3+/-1.2, respectively. In case of CS analysis in soft capsules and liquid preparations, the overall recovery (%) of the spiked CS was 96.79+/-0.53-103.54+/-1.78 and 97.10+/-1.82 to 103.17+/-2.34, respectively. In conclusion, the quantitative analysis of the disaccharides produced by enzymatic digestion can be used in the direct quantitation of CS containing pharmaceutical formulations.

Animals↗
PubMed2005

Variations in matrix composition and GAG fine structure among scaffolds for cartilage tissue engineering.

OBJECTIVE: To compare matrix composition and glycosaminoglycan (GAG) fine structure among five scaffolds commonly used for in vitro chondrocyte culture and cartilage tissue engineering. DESIGN: Bovine articular chondrocytes were seeded into agarose, alginate, collagen I, fibrin and polyglycolic acid (PGA) constructs and cultured for 20 or 40 days. In addition to construct DNA and sulfated GAG (sGAG) contents, the delta-disaccharide compositions of the chondroitin/dermatan sulfate GAGs were determined for each scaffold group via fluorophore-assisted carbohydrate electrophoresis (FACE). RESULTS: Significant differences were found in cell proliferation and extracellular matrix accumulation among the five scaffold groups. Significant cell proliferation was observed for all scaffold types but occurred later (20-40 days) in PGA constructs compared to the other groups (0-20 days). By 40 days, agarose constructs had the highest sGAG to DNA ratio, while alginate and collagen I had the lowest levels. Quantitative differences in the Delta-disaccharide composition of the GAGs accumulated in the different scaffolds were also found, with the most striking variations in unsulfated and disulfated delta-disaccharides. Agarose constructs had the highest fraction of disulfated residues and the lowest fraction of unsulfated residues, with a 6-sulfated/4-sulfated disaccharide ratio most similar to that of native articular cartilage. CONCLUSIONS: The similarities and differences among scaffolds in proteoglycan accumulation and GAG composition suggest that the scaffold material directly or indirectly influences chondrocyte proteoglycan metabolism and may have an influence on the quality of tissue engineered cartilage.

Animals↗
PubMed1979

alpha-L-iduronidase, beta-D-glucuronidase, and 2-sulfo-L-iduronate 2-sulfatase: preparation and characterization of radioactive substrates from heparin.

Radioactive disaccharide substrates for alpha-L-iduronidase, beta-D-glucuronidase, and 2-sulfo-L-iduronate 2-sulfatase have been prepared from heparin by deaminative cleavage followed by reduction with NaBT4. Six disaccharides were isolated from this reaction mixture and identified. Acid hydrolysis of the major disaccharide, O-(alpha-L-idopyranosyluronic acid 2-sulfate)-(1 linked to 4)-(2,5-anhydro-D-mannitol-l-t 6-sulfate (IdAs--Ms), produced 48% of O-(alpha-L-idopyranosyluronic acid)-(1 linked to 4)-(2,5-anhydro-D-mannitol-l-t 6-sulfate) (IdA--Ms) and 25% of O-(alpha-L-idopyranosyluronic acid)-(1 linked to 4)-2,5-anhydro-D-mannitol-l-t. The most-sensitive substrate for determining alpha-L-iduronidase activity was IdA--Ms which, when incubated with leucocyte and skin-fibroblast homogenates prepared from patients having a deficiency of alpha-L-iduronidase (Mucopolysaccharidosis Type I; MPS-I), was hydrolysed to yield 2,5-anhydro-D-mannitol-l-t 6-sulfate at a rate 50-times less than that found for normal control-preparations. Similarly, O-(beta-D-glucopyranosyluronic acid)-(1 linked to 4)-(2,5-anhydro-D-mannitol-l-t 6-sulfate) was degraded by whole-cell homogenates prepared from beta-D-glucuronidase-deficient (Mucopolysaccharidosis, Type VII) fibroblasts, to yield 2,5-anhydro-D-mannitol-l-t 5-sulfate at a rate 60-times less that that found for MPS-I and normal control-preparations. IdAs--Ms was degraded by 2-sulfo-L-iduronate 2-sulfatase at a rate more than 45-times greater than that found for O-(alpha-L-idopyranosyluronic acid 2-sulfate)-(1 linked to 4)-2,5-anhydro-D-mannitol-l-t. C-6 Sulfation of the anhydro-D-mannitol-l-t residue is an important structural determinant in the mechanism of action of both alpha-L-iduronidase and 2-sulfo-L-iduronate 2-sulfatase on disaccharide substrates.

Cells, Cultured↗
PubMed1992

Conformational analysis of the anomeric forms of sophorose, laminarabiose, and cellobiose using MM3.

Relaxed-residue energy maps based on the MM3 force-field were computed for relative orientations of the pyranosyl rings of sophorose, laminarabiose, and cellobiose, respectively the (1----2)-beta-; (1----3)-beta-; and (1----4)-beta-linked D-glucosyl disaccharides. Sixteen starting conformations of the rotatable exocyclic side-groups were considered for each molecule. All of the energy surfaces have two intersecting low-energy troughs and illustrate the importance of exo-anomeric effects in determining disaccharide conformation. Local minima were found by relaxed minimization without restriction. The energy surfaces of these disaccharides are very similar to the energy surfaces of their corresponding 6-methyltetrahydropyran analogues. There is good agreement between disaccharide structures having minimal MM3 energy and those found by crystallography.

Carbohydrate Conformation↗
PubMed2001

Enzymatic syntheses of T antigen-containing glycolipid mimicry using the transglycosylation activity of endo-alpha-N-acetylgalactosaminidase.

Thomsen-Friedenreich antigen (T antigen) disaccharide, beta-D-galactose-(1-->3)-alpha-N-acetyl-D-galactosamine (beta-D-Gal-(1-->3)-alpha-D-GalNAc), containing glycolipid mimicry was synthesized using the transglycosylation activity of endo-alpha-N-acetylgalactosaminidase from Bacillus sp. This enzyme could transfer the disaccharide from a p-nitrophenyl substrate to water-soluble 1-alkanols and other alcohols at a transfer ratio of 70% or more. Although the transfer ratios were lower for water-insoluble than water-soluble alcohols, they were shown to increase by adding sodium cholate to the reaction mixtures. The enzyme also transferred the disaccharide directly from asialofetuin to 1-alkanols. The anomeric bond between the disaccharide and 1-alkanols of the transglycosylation product is in the alpha configuration as determined by sequential digestion of jack bean beta-galactosidase and Acremonium alpha-N-acetylgalactosaminidase. Since the transglycosylation product, beta-D-Gal-(1-->3)-alpha-D-GalNAc-(1-->O)-hexyl, efficiently inhibits the binding of anti-T antigen monoclonal antibody to asialofetuin, it has potential as an agent for blocking T antigen-mediated cancer metastasis.

Alcohols↗
PubMed2003

Remote control of alpha- or beta-stereoselectivity in (1-->3)-glucosylations in the presence of a C-2 ester capable of neighboring-group participation.

In (1-->3)-glucosylation the glycosyl bond originally present in either donor or acceptor is shown to control the stereoselectivity of the forthcoming bond, i.e., the newly formed glycosidic linkage has the opposite anomeric configuration of that of either the donor or acceptor. Therefore, with alpha-(1-->3)-linked disaccharides with nonreducing ends that have the 3-OH free as the acceptor and an acetylated glucosyl trichloroacetimidate as the donor, or with an alpha-(1-->3)-linked acetylated disaccharide trichloroacetimidate as the donor and a glucoside with 3-OH free as the acceptor, beta-linked trisaccharides were obtained. Meanwhile, with beta-(1-->3)-linked disaccharides that have nonreducing ends with the 3-OH free as the acceptor and an acetylated glucosyl trichloroacetimidate as the donor, or with a beta-(1-->3)-linked acetylated disaccharide trichloroacetimidate as the donor and a glucoside with the 3-OH free as the acceptor, alpha-linked trisaccharides were obtained in spite of the C-2 neighboring group participation.

Disaccharides↗
PubMed1996

Synthesis of alpha- and beta-linked tyvelose epitopes of the Trichinella spiralis glycan: 2-acetamido-2-deoxy-3-O-(3,6-dideoxy-D-arabino-hexopyranosyl)-beta -D-galactopyranosides.

The anomeric configuration of tyvelose, 3,6-dideoxy-D-arabino-hexopyranose, in the recently discovered glycan epitopes of the parasite Trichinella spiralis has not been established. Two 2-(trimethylsilyl)ethyl disaccharide glycosides, alpha- and beta-Tyv-(1-->3)-beta-D-GalNAc (4 and 5), have been synthesized to provide model compounds that, together with the methyl 3,6-dideoxy-alpha- and beta-D-arabino-hexopyranosides (2 and 3), aid the determination of the anomeric configuration of tyvelose residues in the parasite glycan, either indirectly by immunochemical inhibition data or directly by the technique of 1H NMR spectroscopy. Methyl 3,6-dideoxy-beta-D-arabino-hexopyranoside (3) was synthesized from methyl 2,3-anhydro-4,6-O-benzylidene-beta-D-mannopyranoside (9) by a method previously used for the alpha anomer 2. Benzylation of 2 provided a route to the glycosyl donor, 2,4-di-O-benzyl-3,6-dideoxy-alpha-D-arabino-hexopyranosyl chloride (30), that reacted with the selectively protected 2-acetamido-2-deoxy-D-galactopyranoside alcohol 18 in the presence of an insoluble silver zeolite catalyst to give the alpha- and beta-linked disaccharides 31 and 32. Glycosylation of the related 2-acetamido-2-deoxy-D-galactopyranoside alcohol 27 by 30 under similar conditions provided disaccharides 33 and 34 containing a tether. Deprotection of the saccharide and derivatization of the tether with 1,2-diaminoethane provided amide derivatives 35 and 36 suitable for the preparation of neoglycoconjugate antigens. Complete 1H and 13C NMR chemical shifts of the deprotected disaccharides and monosaccharides are reported.

Animals↗
PubMed2002

Compositional and structural alterations of chondroitin and dermatan sulfates during the progression of atherosclerosis and aneurysmal dilatation of the human abdominal aorta.

Glycosaminoglycans participate in several biological functions in the arterial wall through their specific structures. They undergo specific compositional and structural modifications during the development of vascular diseases. The present study was performed to determine the variations in the concentration and the structural characteristics of galactosaminoglycans--chondroitin sulfate (CS) and dermatan sulfate (DS)--during the progression of atherosclerosis and aneurysmal dilatation of the human abdominal aorta. The concentration of CS was increased 24% (p < or = 0.05) in atherosclerotic type II aortas, but it was significantly decreased (29%, p < or = 0.05) in atherosclerotic type V aortas and aneurysmal aortas (65%, p < or = 0.01). In contrast, the concentration of DS was almost constant in all stages of arterial disease examined. Significant structural alterations were detected in the disaccharide composition of galactosaminoglycans. The ratio of 6-sulfated to 4-sulfated disaccharides was increased in atherosclerotic type II aortas (4.0 instead of 3.1 in normal aortas) due to the marked increase of CS in this tissue. This ratio was significantly decreased in atherosclerotic type V and aneurysmal aortas (2.1 and 1.6, respectively) due to the significant reduction of CS in the respective tissues. In addition, significant decrease of the oversulfated disaccharides, which are mainly located in DS chains, was recorded in atherosclerotic and aneurysmal aortas. Particularly, deltadi-di(2,6)S were decreased 32% (p < or = 0.01) and 86% (p < or = 0.01) in atherosclerotic type II and V aortas and 88% (p < or = 0.01) in aneurysm. Deltadi-di(2,4)S were increased in atherosclerotic type II aortas (21%, p < or = 0.01), but significantly decreased in atherosclerotic type V (33%, p < or = 0.01) and aneurysmal aortas (56%, p < or = 0.01). The amounts of deltadi-di(4,6)S were not markedly affected in the diseased tissues. These results suggest that the concentration of galactosaminoglycans is differentially affected during the progression of atherosclerosis. Furthermore, the development of vascular disease is associated with specific structural modifications, especially with the significant reduction of particular types of oversulfated disaccharides, which may play essential biological roles in the arterial wall.

Adult↗
PubMed2002

Studies on n-octyl-5-(alpha-D-arabinofuranosyl)-beta-D-galactofuranosides for mycobacterial glycosyltransferase activity.

The mycobacterial cell wall is a potential target for new drug development. Herein we report the preparation and activity of several n-octyl-5-(alpha-D-arabinofuranosyl)-beta-D-galactofuranoside derivatives. A cell-free assay system has been utilized for determination of the ability of disaccharide analogues to act as arabinosyltransferase acceptors using [14C]-DPA as the glycosyl donor. In addition, in vitro inhibitory activity has been determined in a colorimetric broth microdilution assay system against MTB H37Ra and three clinical isolates of Mycobacterium avium complex (MAC). One of these disaccharides showed moderate activity against MTB. The biological evaluation of these disaccharides suggests that more hydrophobic analogues with a blocked reducing end showed better activity as compared to a totally deprotected disaccharide that more closely resembles the natural substrates in cell wall biosynthesis.

Antitubercular Agents↗
PubMed2004

NMR and molecular modeling studies of the interaction between wheat germ agglutinin and the beta-D-GlcpNAc-(1-->6)-alpha-D-Manp epitope present in glycoproteins of tumor cells.

The beta-D-GlcpNAc-(1-->6)-alpha-D-Manp disaccharide is a constituent of highly branched cell-surface glycoconjugates that are malignancy markers. The conformational preference of the disaccharide beta-D-GlcpNAc-(1-->6)-alpha-D-Manp-OMe in solution has been studied by molecular modeling and NMR spectroscopy including 1D (1)H,(1)H T-ROESY experiments and analysis of (3)J(H,H) of the hydroxymethyl group being part of the glycosidic linkage of the disaccharide, which revealed the relative populations of the omega torsion angle as gt = 0.60, gg = 0.35, and tg = 0.05. Good agreement was obtained between the effective proton-proton distances from the experiment and those obtained by molecular modeling when the flexibility at the omega torsion angle was taken into account. Molecular modeling of the disaccharide in the binding sites of the lectin wheat germ agglutinin indicates that several conformations could be adopted in the bound state. (1)H NMR and transfer NOESY experiments confirmed that binding took place, and trans-glycosidic proton-proton interactions indicated that a conformational preference was present in the bound state, as observed by the relative change of the NOEs from H1' to H6(pro-R) and H6(pro-S). STD NMR experiments showed that binding occurred in the region of the N-acetyl group of the terminal sugar residue. In addition, the O-methyl group received saturation transfer because of the proximity to the protein. (1)H,(1)H NOEs indicated that the two methyl groups were close in space, as observed in only one of the predicted bound conformations. Experimental and theoretical data therefore agree that one conformation with a gt conformation of the hydroxymethyl group and a negative sign for the psi torsion angle is indeed selected by the lectin upon binding.

Binding Sites↗