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S Oscarson

Publications and source records attributed to S Oscarson.

At least 19 recordsLinked to original sources
PubMed2001

Syntheses of anomerically phosphodiester-linked oligomers of the repeating units of the Haemophilus influenzae types c and f capsular polysaccharides.

Spacer-equipped dimers and trimers of the repeating units of the capsular polysaccharide of Haemophilus influenzae type c, -4)-3-O-Ac-beta-D-GlcpNAc-(1-->3)-alpha-D-Galp-(1-OPO(3-)-, and type f, -3)-beta-D-GalpNAc-(1-->4)-3-O-Ac-alpha-D-GalpNAc-(1-OPO(3-)-, have been synthesized for use in immunological studies. H-Phosphonate chemistry was used for the formation of the interglycosidic phosphate diester linkages. Two types of building blocks, a spacer glycoside disaccharide starting monomer (15 and 22) and an anomeric monoester alpha-H-phosphonate disaccharide elongating monomer (12 and 27), were built up for each serotype structure from properly protected monosaccharide precursors using mainly thioglycosides as glycosyl donors. Stereospecificity in the formation of the alpha-linked monoester H-phosphonate was possible in type c through crystallization of the pure alpha-anomer of the precursor hemiacetal from an alpha/beta-mixture, whereas in type f, the hemiacetal was isolated directly as exclusively the alpha-anomer. Subsequent phosphonylation using triimidazolylphosphine was performed without anomerization. Formation of the anomeric phosphate diester linkages was performed using pivaloyl chloride as coupling reagent followed by I(2)/H(2)O oxidation of the formed diester H-phosphonates. Original experiments afforded no diester product at all, but optimization of the oxidation conditions (lowering the temperature and dilution with pyridine prior to I(2) addition) gave the dimers in good yields (71% and 81%) and, subsequently, after removal of a temporary silyl protecting group in the dimers, the trimers in fair yields (36% and 37%), accompanied by hydrolysis of the dimer phosphate linkage. One-step deprotection through catalytic hydrogenolysis efficiently afforded the target dimer (30 and 36) and trimer structures (32 and 39). The synthetic scheme allows for further elongation to give higher oligomers.

Bacterial Capsules↗
PubMed2000

One-pot oligosaccharide synthesis exploiting solvent reactivity effects.

[reaction: see text] One-pot syntheses of trisaccharides have been accomplished simply by changing the solvent system between the two subsequent glycosylation reactions and utilizing the difference in glycosylation rate between different solvents. By tuning the reactivity of acceptors and donors and performing the first glycosylation in Et(2)O (low glycosylation rate) and the second in CH(2)Cl(2)/Et(2)O (higher glycosylation rate), trisaccharides were synthesized in high yields (76-84%).

Carbohydrate Sequence↗
PubMed2000

Synthesis of the Lewis b hexasaccharide and squarate acid-HSA conjugates thereof with various saccharide loadings.

The Lewis b hexasaccharide, alpha-L-Fucp-(1 --> 2)-beta-D-Galp-(1 --> 3)-[alpha-L-Fucp-(1 --> 4)]-beta-D-GlcpNAc-(1 --> 3)-beta-D-Galp-(l --> 4)-beta-D-Glcp, has been synthesised using a convergent synthesis. Starting from ethyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside, a thioglycoside tetrasaccharide donor block, was constructed through two orthogonal glycosylations with glycosyl bromide donors. First, the galactose moiety was introduced using silver triflate as a promoter and then the two fucose residues under halide-assisted conditions. Finally, this tetrasaccharide was linked to a spacer-equipped 3I,4I-diol lactose acceptor in a DMTST-promoted coupling to give, after deprotection, the Lewis b hexasaccharide as its 2-aminoethyl spacer-equipped derivative. This was coupled to human serum albumin (HSA), using the squarate ester methodology, in various saccharide-protein ratios, to give neoglycoconjugates with different saccharide loadings in about 50%) efficiency.

Carbohydrate Conformation↗
PubMed2000

Isothermal titration calorimetric studies on the binding of deoxytrimannoside derivatives with artocarpin: implications for a deep-seated combining site in lectins.

The carbohydrate binding specificity of the seed lectin from Artocarpus integrifolia, artocarpin, has been elucidated by the enzyme-linked lectin absorbent assay [Misquith, S., et al (1994) J. Biol. Chem. 269, 30393-30401], wherein it was demonstrated to be a Man/Glc specific lectin with high affinity for the trisaccharide present in the core of all N-linked oligosaccharide chains of glycoproteins. As a consequence of this characterization, the binding epitopes of this trisaccharide, 3, 6-di(alpha-D-mannopyranosyl)-D-mannose, for artocarpin were investigated by isothermal titration calorimetry using its monodeoxy as well as Glc and Gal analogues. The thermodynamic data presented here implicate 2-, 3-, 4-, and 6-hydroxyl groups of the alpha(1-3) Man and alpha(1-6) Man residues, and the 2- and 4-OH groups of the central Man residue, in binding to artocarpin. Nevertheless, alpha(1-3) Man is the primary contributor to the binding affinity, unlike other Man/Glc binding lectins which exhibit a preference for alpha(1-6) Man. In addition, unlike the binding reactions of most lectins reported so far, the interaction of mannotriose involves all of its hydroxyl groups with the combining site of the lectin. Moreover, the free energy and enthalpy contributions to binding of individual hydroxyl groups of the trimannoside estimated from the corresponding monodeoxy analogues show nonlinearity, suggesting differential contributions of the solvent and protein to the thermodynamics of binding of the analogues. Thus, this study not only provides evidence for the extended site recognition of artocarpin for the trimannoside epitope but also suggests that its combining site is best described as a deep cleft as opposed to shallow indentations implicated in other lectins.

Binding Sites↗
PubMed2000

Thermodynamic binding studies of lectins from the diocleinae subtribe to deoxy analogs of the core trimannoside of asparagine-linked oligosaccharides.

Lectins from seven different species of the Diocleinae subtribe have been recently isolated and characterized in terms of their carbohydrate binding specificities (Dam, T. K., Cavada, B. S., Grangeiro, T. B., Santos, C. F., de Sousa, F. A. M., Oscarson, S., and Brewer, C. F. (1998) J. Biol. Chem. 273, 12082-12088). The lectins included those from Canavalia brasiliensis, Cratylia floribunda, Dioclea rostrata, Dioclea virgata, Dioclea violacea, and Dioclea guianensis. All of the lectins exhibited specificity for Man and Glc residues, but much higher affinities for the branched chain trimannoside, 3,6-di-O-(alpha-d-mannopyranosyl)-d-mannose, which is found in the core region of all asparagine-linked carbohydrates. In the present study, isothermal titration microcalorimetry is used to determine the binding thermodynamics of the above lectins, including a new lectin from Canavalia grandiflora, to a complete series of monodeoxy analogs of the core trimannoside. From losses in the affinity constants and enthalpies of binding of certain deoxy analogs, assignments are made of the hydroxyl epitopes on the trimannoside that are involved in binding to the lectins. The pattern of binding of the deoxy analogs is similar for all seven lectins, and similar to that of concanavalin A which is also a member of the Diocleinae subtribe. However, differences in the magnitude of the thermodynamic binding parameters of the lectins are observed, even though the lectins possess conserved contact residues in many cases, and highly conserved primary sequences. The results indicate that non-contact residues in the lectins, even those distant from the binding sites, modulate their thermodynamic binding parameters.

Amino Acid Sequence↗
PubMed2000

Binding of multivalent carbohydrates to concanavalin A and Dioclea grandiflora lectin. Thermodynamic analysis of the "multivalency effect".

Binding of a series of synthetic multivalent carbohydrate analogs to the Man/Glc-specific lectins concanavalin A and Dioclea grandiflora lectin was investigated by isothermal titration microcalorimetry. Dimeric analogs possessing terminal alpha-D-mannopyranoside residues, and di-, tri-, and tetrameric analogs possessing terminal 3, 6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside residues, which is the core trimannoside of asparagine-linked carbohydrates, were selected in order to compare the effects of low and high affinity analogs, respectively. Experimental conditions were found that prevented precipitation of the carbohydrate-lectin cross-linked complexes during the isothermal titration microcalorimetry experiments. The results show that the value of n, the number of binding sites on each monomer of the lectins, is inversely proportional to the number of binding epitopes (valency) of each carbohydrate. Hence, n values close to 1.0, 0.50, and 0.25 were observed for the binding of mono-, di-, and tetravalent sugars, respectively, to the two lectins. Importantly, differences in the functional valency of a triantennary analog for concanavalin A and D. grandiflora lectin are observed. The enthalpy of binding, DeltaH, is observed to be directly proportional to the number of binding epitopes in the higher affinity analogs. For example, DeltaH of a tetravalent trimannoside analog is nearly four times greater than that of the corresponding monovalent analog. Increases in K(a) values of the multivalent carbohydrates relative to monovalent analogs, known as the "multivalency effect," are shown to be due to more positive entropy (TDeltaS) contributions to binding of the former sugars. A general thermodynamic model for distinguishing binding of multivalent ligands to a single receptor with multiple, equal subsites versus binding to separate receptor molecules is given.

Calorimetry↗
PubMed1998

Thermodynamics of binding of the core trimannoside of asparagine-linked carbohydrates and deoxy analogs to Dioclea grandiflora lectin.

The Man/Glc-specific seed lectin from Dioclea grandiflora (DGL) is a member of the Diocleinae subtribe that includes the jack bean lectin concanavalin A (ConA). Both DGL and ConA bind with high affinity to the "core" trimannoside moiety, 3, 6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside, which is present in asparagine-linked carbohydrates. Recent hemagglutination inhibition studies suggest that DGL and ConA recognize similar epitopes of the trisaccharide but possess different binding specificities for complex carbohydrates (Gupta, D., Oscarson, S., Raju, T. S., Stanley, P., Toone, E. J., and Brewer, C. F. (1996) Eur. J. Biochem. 242, 320-326). In the present study, we have used isothermal titration microcalorimetry to determine the thermodynamics of binding of DGL to a complete set of monodeoxy analogs of the core trimannoside as well as a tetradeoxy analog. The thermodynamic data indicate that DGL recognizes the 2-, 3-, 4-, and 6-hydroxyl groups of the alpha(1,6) Man residue, the 3- and 4-hydroxyl group of the alpha(1, 3) Man residue, and the 2- and 4-hydroxyl groups of the central Man residue of the trimannoside. The thermodynamic data for the tetradeoxy analog lacking the 3- and 4-hydroxyl group of the alpha(1, 3) Man residue, and the 2- and 4-hydroxyl groups of the central Man residue of the trimannoside are consistent with the involvement of these hydroxyl groups in binding. While the overall pattern of data for DGL binding to the deoxy analogs is similar to that for ConA (Gupta, D., Dam, T. K., Oscarson, S., and Brewer, C. F. (1997) J. Biol. Chem. 272, 6388-6392), differences exist in the data for certain monodeoxy analogs binding to the two lectins. Differences are also observed in the thermodynamics of binding of DGL and ConA to a biantennary complex carbohydrate. In the following paper (Rozwarski, D. A., Swami, B. M., Brewer, C. F., and Sacchettini, J. C. (1998) J. Biol. Chem. 273, 32818-32825), the x-ray crystal structure of DGL complexed to the core trimannoside is presented, and a comparison is made of the thermodynamic binding data for DGL and ConA as well as the structures of their respective trimannoside complexes.

Asparagine↗
PubMed1998

Differential solvation of "core" trimannoside complexes of the Dioclea grandiflora lectin and concanavalin A detected by primary solvent isotope effects in isothermal titration microcalorimetry.

The thermodynamics of binding of the Man/Glc-specific seed lectin from Dioclea grandiflora (DGL) to deoxy analogs of the "core" trimannoside, 3, 6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside was determined by isothermal titration microcalorimetry (ITC) in the first paper of this series (Dam, T. K., Oscarson, S., and Brewer, C. F. (1998) J. Biol. Chem. 273, 32812-32817). The data showed binding of specific hydroxyl groups on all three residues of the trimannoside, similar to that observed for ConA (Gupta, D., Dam, T. K., Oscarson, S., and Brewer, C. F. (1997) J. Biol. Chem. 272, 6388-6392). However, differences exist in the thermodynamics of binding of monodeoxy analogs of the alpha(1-6) Man residue of the trimannoside to the two lectins. The x-ray crystal structure of DGL complexed to the core trimannoside, presented in the second paper in this series (Rozwarski, D. A., Swami, B. M., Brewer, C. F., and Sacchettini, J. C. (1998) J. Biol. Chem. 273, 32818-32825), showed the overall structure of the complex to be similar to that of the ConA-trimannoside complex. Furthermore, the trimannoside is involved in nearly identical hydrogen bonding interactions in both complexes. However, differences were noted in the arrangement of ordered water molecules in the binding sites of the two lectins. The present study presents ITC measurements of DGL and ConA binding to the monodeoxy analogs of the trimannoside in hydrogen oxide (H2O) and deuterium oxide (D2O). The solvent isotope effects present in the thermodynamic binding data provide evidence for altered solvation of the parent trimannoside complexes at sites consistent with the x-ray crystal structures of both lectins. The results indicate that the differences in the thermodynamics of DGL and ConA binding to alpha(1-6) monodeoxy analogs of the trimannoside do not correlate with solvation differences of the parent trimannoside complexes.

Calorimetry↗
PubMed1998

Diocleinae lectins are a group of proteins with conserved binding sites for the core trimannoside of asparagine-linked oligosaccharides and differential specificities for complex carbohydrates.

The seed lectin from Dioclea grandiflora and jack bean lectin concanavalin A (ConA) are both members of the Diocleinae subtribe of Leguminosae lectins. Both lectins have recently been shown to possess enhanced affinities and extended binding sites for the trisaccharide, 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannose, which is present in the core region of all asparagine-linked carbohydrates (Gupta, D., Oscarson, S., Raju, S., Stanley, P. Toone, E. J. and Brewer, C. F. (1996) Eur. J. Biochem. 242, 320-326). In the present study, the binding specificities of seven other lectins from the Diocleinae subtribe have been investigated by hemagglutination inhibition and isothermal titration microcalorimetry (ITC). The lectins are from Canavalia brasiliensis, Canavalia bonariensis, Cratylia floribunda, Dioclea rostrata, Dioclea virgata, Dioclea violacea, and Dioclea guianensis. Hemagglutination inhibition and ITC experiments show that all seven lectins are Man/Glc-specific and have high affinities for the core trimannoside, like ConA and D. grandiflora lectin. All seven lectins also exhibit the same pattern of binding to a series of monodeoxy analogs and a tetradeoxy analog of the trimannoside, similar to that of ConA and D. grandiflora lectin. However, C. bonariensis, C. floribunda, D. rostrata, and D. violacea, like D. grandiflora, show substantially reduced affinities for a biantennary complex carbohydrate with terminal GlcNAc residues, while C. brasiliensis, D. guianensis, and D. virgata, like ConA, exhibit affinities for the oligosaccharide comparable with that of the trimannoside. Thermodynamic data obtained by ITC indicate different energetic mechanisms of binding of the above two groups of lectins to the complex carbohydrate. The ability of the lectins to induce histamine release from rat peritoneal mast cells is shown to correlate with the relative affinities of the proteins for the biantennary carbohydrate.

Animals↗
PubMed1998

Synthesis of a tri- and tetradeoxy analogue of methyl 3,6-di-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside for investigation of the binding site of various plant lectins.

The synthesis of a the 2,4,3'-trideoxy and 2,4,3',4'-tetradeoxy analogues of the trimannoside part of the core structure of N-linked glycoproteins, methyl 3,6-di-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside, is described. A 2,4-dideoxy (1-->6) linked disaccharide was used as a common intermediate acceptor, which was coupled with a 3-deoxy and a 3,4-dideoxy benzochlorosugar donor, the latter prepared from methyl alpha-D-mannopyranoside in five steps. Despite the acid-sensitive donors and acceptor, acceptable glycosylation yields were obtained of both the trideoxy- and the tetradeoxy trisaccharide using silver triflate as a promoter (65 and 51%, respectively). Deprotection in one step then gave the target products.

Binding Sites↗
PubMed1997

Synthesis of colitose-containing oligosaccharide structures found in polysaccharides from Vibrio cholerae O139 synonym Bengal using thioglycoside donors.

The syntheses of the two colitose-containing trisaccharides 8-methoxycarbonyloctyl (3,6-dideoxy-alpha-L-xylo-hexopyranosyl)-(1-->2)-beta-D-galactopyranosyl -(1-->3)-2-acetamido-2-deoxy-beta-D-glucopyranoside and 8-methoxycarbonyloctyl beta-D-galactopyranosyl-(1-->3)-[(3,6- dideoxy-alpha-L-xylo-hexopyranosyl)-(1-->4)]-2-acetamido-2-deoxy-beta-D- glucopyranoside, and tetrasaccharide 8-methoxycarbonyloctyl (3,6-dideoxy-alpha-L-xylo-hexopyranosyl)-(1-->2)-beta-D-galactopyranosyl - (1-->3)-[(3,6-dideoxy-alpha-L-xylo-hexopyranosyl)-(1-->4)]-2-acetamido-2 -deoxy- beta-D-glucopyranoside are described. The oligosaccharides correspond to structures found in the capsular polysaccharide and the lipopolysaccharide of Vibrio cholerae O139 and also to lipopolysaccharide structures of E. coli O55 and Salmonella greenside. The colitose residues were introduced via dimethyl(methylthio)sulfonium trifluoromethanesulfonate promoted glycosylations using colitose thioglycosides as glycosyl donors.

Bacterial Capsules↗
PubMed1997

Thermodynamics of lectin-carbohydrate interactions. Binding of the core trimannoside of asparagine-linked carbohydrates and deoxy analogs to concanavalin A.

The trisaccharide 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannose, which is present in all asparagine-linked carbohydrates, was previously shown by titration microcalorimetry to bind to the lectin concanavalin A (ConA) with nearly -6 kcal mol-1 greater enthalpy change and 60-fold higher affinity than methyl-alpha-D-mannopyranoside (Mandal, D. K., Kishore, N., and Brewer, C. F. (1994) Biochemistry 33, 1149-1156). Similar studies of the binding of a series of monodeoxy derivatives of the alpha(1-3) residue of the trimannoside showed that this arm was required for high affinity binding (Mandal, D. K., Bhattacharyya, L., Koenig, S. H., Brown, R. D., III, Oscarson, S., and Brewer, C. F. (1994) Biochemistry 33, 1157-1162). In the present paper, a series of monodeoxy derivatives of the alpha(1-6) arm and "core" Man residue of the trimannoside as well as dideoxy and trideoxy analogs were synthesized. Isothermal titration microcalorimetry experiments establish that the 3-, 4-, and 6-hydroxyl groups of the alpha(1-6)Man residue of the trimannoside binds to the lectin, along with the 2- and 4-hydroxyl groups of the core Man residue and the 3- and 4-hydroxyl groups of the alpha(1-3)Man residue. Dideoxy analogs and trideoxy analogs showed losses of affinities and enthalpy values consistent with losses in binding of specific hydroxyl groups of the trimannoside. The free energy and enthalpy contributions to binding of individual hydroxyl groups of the trimannoside determined from the corresponding monodeoxy analogs are observed to be nonlinear, indicating differential contributions of the solvent and protein to the thermodynamics of binding of the analogs. The thermodynamic solution data agree well with the recent x-ray crystal structure of ConA complexed with the trimannoside (Naismith, J. H., and Field, R. A. (1996) J. Biol. Chem. 271, 972-976).

Calorimetry↗
PubMed1997

Synthesis of L-glycero-D-manno-heptopyranose-containing oligosaccharide structures found in lipopolysaccharides from Haemophilus influenzae.

Syntheses are described of the tetrasaccharide 2-(4-trifluoroacetamidophenyl)ethyl O-(beta-D-galactopyranosyl)-(1-->2)-O- (L-glycero-alpha-D-manno-heptopyranosyl)-(1-->2)-O-(L-glycero-alpha-D- manno-heptopyranosyl)-(1-->3)-L-glycero-alpha-D-manno-heptopyranoside (20) and the three trisaccharides 2-(4-trifluoroacetamidophenyl)ethyl O-(L-glycero-alpha-D-manno-heptopyranosyl)-(1-->2)-O-(L-glycero-alpha-D- manno-heptopyranosyl)-(1-->3)-L-glycero-alpha-D-manno-heptopyranoside (17), 2-(4-trifluoroacetamidophenyl)ethyl O-(beta-D-glucopyranosyl)-(1-->4)- O-(beta-D-glucopyranosyl)-(1-->4)-L-glycero-alpha-D-manno-heptopyrano side (5), and 2-(4-trifluoro-acetamidophenyl)ethyl O-(beta-D-galactopyranosyl)-(1-->4)-O-(beta-D-glucopyranosyl)-(1-->4)- L-glycero-alpha-D-manno-heptopyranoside (8), corresponding to structures found in the lipooligosaccharides of Haemophilus influenzae.

Carbohydrate Conformation↗
PubMed1996

A comparison of the fine saccharide-binding specificity of Dioclea grandiflora lectin and concanavalin A.

The lectin from the seeds of Dioclea grandiflora (DGL) is a Man/Glc-specific tetrameric protein with physical and saccharide-binding properties reported to be similar to that of the jack bean lectin concanavalin A (ConA). Unlike other plant lectins, both DGL and ConA bind with high affinity to the core trimannoside moiety, 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside, which is present in all asparagine-linked carbohydrates. In the present study, hemagglutination inhibition techniques have been used to investigate binding of DGL and ConA to a series of mono- and dideoxy analogs of methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside and to a series of asparagine-linked oligomannose and complex oligosaccharides and glycopeptides. The results indicate that both DGL and ConA recognize epitopes on all three residues of the trimannoside: the 3-, 4-, and 6-hydroxyl groups of the alpha(1-6)Man residue, the 3-hydroxyl group of the alpha(1-3)Man residue, and the 2- and 4-hydroxyl groups of the central Man residue of the core trimannoside. However, unlike ConA, DGL does not bind to biantennary complex carbohydrates. This was confirmed by showing that biantennary complex glycopeptides do not bind to a DGL-Sepharose affinity column. Unlike ConA, DGL does not show enhanced affinity for a large N-linked oligomannose carbohydrate (Man9 glycopeptide) relative to the trimannoside. Thus, DGL and ConA share similar epitope recognition of the core trimannoside moiety. However, they exhibit differences in their fine specificities for larger N-linked oligomannose and complex carbohydrates.

Carbohydrate Conformation↗
PubMed1996

Synthesis of oligosaccharides corresponding to structures found in capsular polysaccharides of Cryptococcus neoformans--II.

Formula 1 depicts a generalized structure of the capsular polysaccharides of four serotypes of the opportunistic microorganism Cryptococcus neoformans, which appears as one of the major infections in the late stages of development of AIDS. Syntheses are now described of two tetrasaccharides with corresponding structures. These are methyl O-alpha-D-mannopyranosyl-(1-->3)-[O-beta-D-xylopyranosyl-(1-->2)] -O-alpha-D-mannopyranosyl-(1-->3)-alpha-D-mannopyranoside and methyl O-alpha-D-mannopyranosyl-(1-->3)-[O-beta-D-glucopyranosyluronic acid-(1-->2)]-O-alpha-D-mannopyranosyl-(1-->3)-alpha-D-mannopyranoside.

Carbohydrate Conformation↗
PubMed1995

Syntheses of deoxy analogues of methyl 3,6-di-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside for studies of the binding site of concanavalin A.

All of the monodeoxy analogues of methyl 3,6-di-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside have been synthesized together with two dideoxy (2,3'- and 4,3'-) analogues. The 2'- and 2"-deoxy functions were introduced by NIS-promoted couplings with 2,3,4-tri-O-acetyl-D-glucal as donor, followed by reduction of the resulting 2'- and 2"-iodo derivatives, whereas the 3'-, 3"-, 4'-, 4"-, 6'-, and 6"-deoxy functions were introduced by using known deoxyglycosyl chlorides as donors in coupling reactions promoted by silver trifluoromethanesulfonate. The 2- and 4-deoxy functions on the central mannose residue were introduced by displacement, using triiodoimidazole and triphenylphosphine, of a hydroxyl group by iodine on suitably protected derivatives followed by reduction of the resulting iodo analogues.

Binding Sites↗