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PubMed2005

Rapid analysis of oligosaccharides derived from glycoproteins by microchip electrophoresis.

A novel method for fast profiling of complex oligosaccharides released from glycoproteins based on microchip electrophoresis (mu-CE) is presented here. The characterization of separation conditions, i.e., the composition, concentration and pH of running buffer as well as the applied voltage, has been performed using maltose (G2), cellobiose ( G2'), maltriose (G3) and panose (G3') as oligosaccharide isomer models. In mu-CE, much better separation of oligosaccharide isomers and oligosaccharide ladder was obtained in phosphate buffer than in borate buffer over a wide pH range. Under optimal conditions, high-performance separation of the N-linked complex oligosaccharides released from ribonuclease B, fetuin, alpha1-acid glycoprotein (AGP) and IgG was achieved using polymethylmethacrylate (PMMA) microchips with an effective separation channel of 30 mm. These results represent the first reported analysis of the N-linked oligosaccharides derived from glycoproteins by mu-CE, indicating that the present mu-CE-based method is a promising alternative for characterization of the N-linked oligosaccharides in glycoproteins.

Carbohydrate Sequence↗
PubMed1977

Comparison of the action of glucoamylase and glucosyltransferase on D-glucose, maltose, and malto-oligosaccharides.

The action patterns of glucoamylase (amyloglucosidase) and glucosyltransferase (transglucosylase) on D-[1-14C]glucose, [1-14C]maltose, and [1-14C]malto-oligosaccharides (labeled at position 1 of the D-glucose group at the reducing end) have been investigated by paper-chromatographic and oligosaccharide-mapping techniques. Under the conditions of the experiments, the extent of conversion of D-glucose and of maltose into new oligosaccharides was 2.2 and 1.9% with glucoamylase, and 5.7 and 33% with glucosyltransferase. The major oligosaccharides produced by both enzymes were isomaltose (6-O-alpha-D-glucopyranosyl-alpha-D-glucose), panose (O-alpha-D-glucopyranosyl (1 leads to 6)-O-alpha-D-glucopyranosyl-(1 leads to 4)-alpha-D-glucose), and nigerose (3-O-alpha-D-glucopyranosyl-alpha-D-glucose). The glucosyltransferase also synthesized oligosaccharides from malto-oligosaccharides of higher molecular weight to yield compounds having alpha-(1 leads to 6)-linked D-glucosyl groups at the non-reducing ends. Glucoamylase exhibited little, if any, such activity on malto-oligosaccharides.

Glucan 1,4-alpha-Glucosidase↗
PubMed2000

Conformational studies of the glycopeptide Ac-Tyr-[Man5GlcNAc-beta-(1-->4)GlcNAc-beta-(1-->Ndelta)]-Asn-Leu-Thr-Se r-OBz and the constituent peptide and oligosaccharide.

Glycopeptides of desired structure can be conveniently prepared by the coupling of reducing oligosaccharides to aspartic acid of peptides via their glycosylamines formed in the presence of saturated aqueous ammonium hydrogen carbonate. The resulting oligosaccharide chains are N-linked to asparagine as in natural glycoproteins, allowing different peptide oligosaccharide combinations to be analysed for conformational effects. In the present paper, a pentapeptide of ovalbumin was coupled to Man5GlcNAc2 oligosaccharide and the glycopeptide and the two parent compounds compared by NMR ROESY experiments and molecular dynamics simulations. Despite the small size of the peptide, conformational effects were observed suggestive of the oligosaccharide stabilising the peptide in solution and of the peptide influencing oligosaccharide conformation. These effects are relevant to the function of glycosylation and the enzymic processing of oligosaccharide chains.

Carbohydrate Conformation↗
PubMed1990

Analysis of glycoprotein-derived oligosaccharides by high-pH anion-exchange chromatography.

The technique of high-pH anion-exchange chromatography with pulsed amperometric detection has recently been shown to be a powerful method for resolving closely related oligosaccharides [M. R. Hardy and R. R. Townsend, Proc. Natl. Acad. Sci. U.S.A., 85 (1988) 3289-3293]. This report describes separations involving a total of nineteen different high-mannose, hybrid and complex-type oligosaccharides isolated after peptide: N-glycosidase F (PNGase F) or endo-beta-N-acetylglucosaminidase H digestion of glycoproteins. Separations were carried out at a constant base concentration (0.1 M NaOH) using linear gradients from 0 to 0.2 M sodium acetate. The applicability of this chromatography for profiling the N-linked oligosaccharides of glycoproteins was demonstrated by generating "oligosaccharide maps" of PNGase F-liberated oligosaccharides from recombinant human tissue plasminogen activator, ribonuclease b, human transferrin, and bovine fetuin. Methods for recovering salt-free oligosaccharides after this chromatography were also investigated. On-line ion suppression with an anionic micromembrane suppressor cartridge was found to be capable of effective desalting up to a total sodium ion concentration of 0.15-0.2 M at a flow-rate of 1 ml/min. After high-pH anion-exchange chromatography with ion suppression, collected oligosaccharides were analyzed by fast-atom bombardment mass spectrometry after conversion to permethyl derivatives or after reductive amination with rho-aminobenzoic acid ethyl ester.

Animals↗
PubMed2003

Improved capillary electrophoretic separation and mass spectrometric detection of oligosaccharides.

We have developed a CE method for the separation of structural isomers of oligosaccharides labeled with N-quaternized benzylamine. Oligosaccharides with reducing ends were derivatized with benzylamine by reductive amination followed by quaternization to yield a fixed cation label. The benzylamine-derivatized oligosaccharides were analyzed by CE-UV in ammonium acetate buffer and off-line matrix-assisted laser desorption ionization (MALDI) MS. The method was applied to a 1 nmol sample of a model oligosaccharide (LNDFH 1). From this sample a 38 fmol diluted standard was detected. The quaternization of benzylamine-labeled products significantly improved CE separation of neutral oligosaccharides along with several structural isomers. Two hexasaccharide isomers (LNDFH I and LNDFH II) were baseline resolved using an ammonium acetate buffer. This method was also applied successfully to the profiling of oligosaccharides released from the glycoprotein RNase B. The release of 6 pmol of glycans followed by workup showed the detection of all components, with one component corresponding to 100 fmol. Micropreparative collection of CE enabled successful off-line CE-MALDI-MS without additional sample clean up. This report provides a simple and rapid method to separate and analyze oligosaccharides.

Buffers↗
PubMed1997

A unique, terminally glucosylated oligosaccharide is a common feature on Leishmania cell surfaces.

The structures of N-linked oligosaccharides from various Leishmania life-cycle stages and species have been investigated in order to elucidate differences which may be correlated with virulence or tissue tropisms. The structure of gp63 glycans from L major log- and stationary-phase promastigotes were elucidated and compared with the total membrane associated oligosaccharides from five Leishmania spp. L. major gp63 glycans from promastigotes in either log or stationary phases of their growth cycle were shown to have two neutral oligosaccharides having Bio-Gel P4 hydrodynamic volumes of 10.5 and 9.6 glucose units (GU). Sequential exoglycosidase digestion, fragmentation by acetolysis and methylation analysis of hydrazine released glycans, revealed the structure of G9.6 to be a biantennary oligomannose type, having the composition Man6GlcNAc2. These data were confirmed by structural analysis of gp63 oligosaccharides released by digestion with endo-beta-N-acetylglucosaminidase H (Endo-H) and N-glycanase F. The larger glycan was found to be terminally glucosylated, having the composition GlcMan6GlcNAc2. These oligosaccharides were found to occupy only two of the three predicted N-linked glycosylation sites in the L. major gp63 molecule, at positions 300 and 407. On comparison with glycans from other Leishmania spp. and strains, these two oligosaccharides were consistently found to be the predominant promastigote structures. Following transformation to the amastigote stage, alterations in N-linked oligosaccharides appeared to be less consistent between species. L. m. mexicana amastigotes were found to display the same G10.5 and G9.6 glycans found on promastigotes while L. donovani LV9 amastigotes were found to be devoid of N-linked glycans.

Animals↗
PubMed1998

Oat bran beta-gluco- and xylo-oligosaccharides as fermentative substrates for lactic acid bacteria.

The influence of oat bran oligosaccharides on carbohydrate utilization and fermentation end-products was studied with reference to three different lactic acid bacteria (LAB: Lactobacillus rhamnosus, Lactobacillus plantarum and Lactococcus lactis). The main results were that all three LAB utilized oat beta-gluco-oligosaccharides, while only L. plantarum utilized xylo-oligosaccharides. The main products of LAB metabolism were lactic acid, acetic acid, formic acid and ethanol. The results indicated that oat beta-gluco-oligosaccharides and xylo-oligosaccharides induce LAB to form the end-products of a typical mixed-acid fermentation. The formation of mixed-acid production from xylo-oligosaccharides was mainly due to the starvation of cells. This study indicates that oat bran oligosaccharides affect both qualitatively and quantitatively the fermentation end-products of LAB grown on these substrates. This should be taken into account when selecting strains for new fermented cereal based food products.

Acetic Acid↗
PubMed2001

Partial characterization of oligosaccharides expressed on midgut microvillar glycoproteins of the mosquito, Anopheles stephensi Liston.

Midguts of the malaria-transmitting mosquito, Anopheles stephensi, were homogenized and microvillar membranes prepared by calcium precipitation and differential centrifugation. Oligosaccharides present on the microvillar glycoproteins were identified by lectin blotting before and after in vitro and in situ treatments with endo- and exo-glycosidases. Twenty-eight glycoproteins expressed a structurally restricted range of terminal sugars and oligosaccharide linkages. Twenty-three glycoproteins expressed oligomannose and/or hybrid N-linked oligosaccharides, some with alpha1-6 linked fucose as a core residue. Complex-type N-linked oligosaccharides on eight glycoproteins all possessed terminal N-acetylglucosamine, and alpha- and beta-linked N-acetylgalactosamine. Eight glycoproteins expressed O-linked oligosaccharides all containing N-acetylgalactosamine with or without further substitutions of fucose and/or galactose. Galactosebeta1-3/4/6N-acetylglucosamine-, sialic acidalpha2-3/6galactose-, fucosealpha1-2galactose- and galactosealpha1-3galactose- were not detected. Terminal alpha-linked N-acetylgalactosamine residues on N-linked oligosaccharides are described for the first time in insects. The nature and function of these midgut glycoproteins have yet to be identified, but the oligosaccharide side chains are candidate receptors for ookinete binding and candidate targets for transmission blocking strategies.

Animals↗
PubMed2000

Sequencing of sulfated oligosaccharides from mucins by liquid chromatography and electrospray ionization tandem mass spectrometry.

As part of a strategy for profiling diverse mixtures of sulfated mucin-derived oligosaccharides, liquid chromatography coupled to electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the negative ion mode has been explored. Two mixtures of sulfated oligosaccharide alditols from porcine stomach and large intestine were analyzed by straight phase chromatography using an amino-bonded column connected to a Q-TOF instrument. Nine sulfated mucin-derived oligosaccharide alditols from porcine stomach underwent extensive fragmentation allowing determination of their sequence. The fragmentation generated primary, secondary, and tertiary fragment ions informative for the elucidation of the saccharide sequence and localization of the sulfate group. From a single chromatographic analysis, the sequences of 28 different sulfated mucin oligosaccharide alditols purified from porcine large intestine were elucidated, revealing information concerning prominent core sequences and terminal blood group-type epitopes. Analysis of these two sulfated oligosaccharide mixtures demonstrated the usefulness of HPLC-ESI-MS/MS: the on-line separation of multiple isomeric suffated oligosaccharides as present in biological samples, informative fragmentation allowing the identification of the sequence of nonderivatized oligosaccharides, and a sensitivity sufficient for the analysis of quantities as obtained from natural sources.

Animals↗
PubMed2004

Normal-phase nanoscale liquid chromatography-mass spectrometry of underivatized oligosaccharides at low-femtomole sensitivity.

We here describe the online liquid chromatography (LC) electrospray ionization mass spectrometry (MS) of underivatized glycans using a nanoscale normal-phase amide column at a flow rate of 300 nL/min. Retention on the amide column is based on polar interactions of the oligosaccharide hydroxyl groups with the stationary phase, and thus, the retention time predictably increases with elongation of the oligosaccharide chain. The system is characterized by its high chromatographic resolution, which routinely allows the separation of isobaric structures. Separation of oligosaccharide mixtures over a 1-h range permits the detailed characterization of the different species by multiple ion selection and fragmentation steps using ion trap MS. The here presented miniaturization of the online-LC system to the nanoscale in combination with ion trap MS allows the detection of oligosaccharide species in a mixture at low-femtomole sensitivity. Online normal-phase nano-LC-MS of complex oligosaccharide mixtures further facilitates the sensitive and detailed structural analysis of oligosaccharides by overcoming the need for cumbersome and time-consuming derivatization procedures such as reductive amination for labeling with hydrophobic fluorophores or labeling with tritium. The method should be useful for the sensitive and quick analysis of glycosylation patterns and individual oligosaccharides from biotechnologically produced glycoproteins as well as scarcely available biological samples.

Amides↗
PubMed2004

Method for the comparative glycomic analyses of O-linked, mucin-type oligosaccharides.

A method is presented for the direct relative quantitation of distinct O-linked mucin-type oligosaccharides. Mucin-type oligosaccharides are found in a host of tissues from anuran to humans. Because they are often associated with extracellular matrix, they play important roles in cell-cell recognition. Changes in glycosylation of O-linked oligosaccharides are associated with diseases such as cancer. In fertilization, they play an active role in sperm-egg recognition. We describe a method for observing changes in glycosylation of mucin-type oligosaccharides by incorporating deuterium in the release procedure. Oligosaccharides from two different sources are released separately by sodium tetrahydroborate and sodium tetradeuterioborate. The oligosaccharides are combined and separated into components by HPLC. By observing the ratio of deuterated and undeuterated species, changes in glycosylation are precisely quantified. This method is illustrated with mucin-type oligosaccharides from the egg jelly coat of the anuran Xenopus laevis.

Animals↗
PubMed1996

Bifunctional labeling reagent for oligosaccharides to incorporate both chromophore and biotin groups.

We have developed a convenient and effective method for biotinylation of oligosaccharides at their reducing ends. A novel biotin hydrazide having a phenyl group produced the biotin adduct of N-acetyllactosamine (LacNAc) by simple incubation at 90 degrees C for 1 h. Although the biotin adduct was obtained as a mixture of several stereoisomers, one of the isomers, cyclic beta-glycoside, became predominant upon letting the reaction mixture stand in a weakly acidic state (pH 3.5). This conversion may be very advantageous for functional analysis of oligosaccharides because natural N-linked oligosaccharides exist in the cyclic beta form. The limit of detection of labeled LacNAc in reversed-phase chromatography was 330 fmol and showed good linearity in the range from 330 fmol to 261 pmol. When this procedure was applied to complex type and high mannose type N-linked oligosaccharides, the labeled oligosaccharides were easily detected and separated by reversed-phase, gel filtration, and anion exchange chromatographies. Furthermore, these labeled oligosaccharides were able to be immobilized onto the solid phase using avidin-biotin technology and were stable enough to allow the binding assay to be performed repeatedly and under the conditions for in situ exoglycosidase digestion. These results suggest that this derivatization technique might be useful for both separation and functional analysis of oligosaccharides.

Biosensing Techniques↗
PubMed1999

Anion dopant for oligosaccharides in matrix-assisted laser desorption/ionization mass spectrometry.

A new anion dopant for oligosaccharides is developed for use in matrix-assisted laser desorption/ionization mass spectrometry. Two types of sulfate-attached quasimolecular ions are formed in the negative ion mode when neutral oligosaccharides are doped with dilute H2SO4 solutions. Under mild conditions, i.e., low H2SO4 concentration (approximately 10(-3) M) and threshold laser fluence, a sulfate adduct [M + HSO4]- is formed. With more concentrated H2SO4 solutions (approximately 10(-2) M) and higher laser fluence, in situ derivatization of the oligosaccharides occurs to produce an ion whose m/z corresponds to a sulfate derivative [M + HSO4 - H2O]-. Hydrogen sulfate appears to be a general anion dopant because it forms complexes with a wide variety of neutral oligosaccharides. Conversely, anionic oligosaccharides form neither the adduct nor the derivative. The combination of complex formation (with neutral oligosaccharides) and the deprotonation of acidic oligosaccharides allows simultaneous detection of the respective mixture.

Anions↗
PubMed1984

Interaction of cholera toxin with gangliosides: differential effects of the oligosaccharide of ganglioside GM1 and of micellar gangliosides.

Ultraviolet difference absorption spectra of cholera toxin and its B protomer produced by the oligosaccharide moiety of the monosialoganglioside GM1 were measured as a function of the oligosaccharide concentration. In the presence of oligosaccharide, the spectrum is characterized by three peaks at 282, 288, and 292 nm. A linear increase in difference absorption was observed at these wavelengths vs. oligosaccharide concentration; a saturation effect occurred when the molar ratio of oligosaccharide to cholera toxin was higher than 5. The features of the spectra indicated that the binding with the oligosaccharide affected the environment of tryptophan and tyrosine residues of protomer B. In good agreement with the above results, circular dichroic spectra indicated also a local effect of the binding, mostly restricted to protomer B, while the residues of protomer A remained largely unperturbed. Difference absorption spectra were also measured for cholera toxin in the presence of ganglioside and detergent micelles. The employed gangliosides GD1a and GT1b, unable to bind cholera toxin, interact with the protein by way of contaminating traces of GM1. The preparations of GD1a and GT1b contained 0.8-1.0% (w/w) and 0.4-0.5% (w/w) of GM1, respectively. The results obtained with ganglioside GD1a and GT1b in contrast with the observations made with the oligosaccharide of GM1 indicated a major conformational change of the toxin structure. Upon comparison of the conformational change induced by ganglioside micelles with that induced by sodium dodecyl sulfate it may be suggested that the ganglioside micelle, behaving as a detergent, alters the structure of the toxin such as to induce the penetration of protomer A into the lipid milieu.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholera Toxin↗
PubMed1986

Neoglycoproteins: preparation and properties of complexes of biotinylated asparagine-oligosaccharides with avidin and streptavidin.

Neoglycoproteins in which the oligosaccharide moieties are attached noncovalently to the protein through a high-affinity ligand have been prepared from biotinylated oligosaccharides and avidin or the nonglycosylated microbial analogue streptavidin. One of the asparagine-oligosaccharides purified from Pronase-digested ovalbumin (Man6-GlcNAc2-Asn) was reacted with an excess of the hydroxysuccinimide ester of biotin or, for the purpose of quantitation, [3H]biotin. Derivatives were also prepared with an extension "arm", a 6-aminohexanoyl group, between biotin and asparagine. When the purified biotinyl-Asn-oligosaccharide was added to avidin or streptavidin, a complex was formed containing 3 mol of oligosaccharide/mol of protein. The complexes were stable at neutral pH in the absence of biotin and could be dialyzed for 2 weeks without any significant loss of ligand. In the presence of biotin, or under denaturing conditions, the oligosaccharide derivative was released and could be quantitatively recovered. To assess the influence of the protein matrix on the reactivity of the oligosaccharide units, free biotinyl-Asn-oligosaccharide and the corresponding avidin and streptavidin complexes were exposed to alpha-mannosidase in parallel experiments. The rate of hydrolysis of the free derivative was severalfold faster than that of the two protein complexes, and at the time when about 90% of the free derivative had all five alpha-mannosyl residues removed, the majority of the protein-bound derivatives contained two to four undigested alpha-mannosyl residues and also had a significant amount of undigested starting material. The ease of preparation and the properties of these neoglycoproteins suggest that they should be excellent models for the study of glycoprotein-receptor binding and glycoprotein processing.

Asparagine↗
PubMed1988

Precipitation of galactose-specific lectins by complex-type oligosaccharides and glycopeptides: studies with lectins from Ricinus communis (agglutinin I), Erythrina indica, Erythrina arborescens, Abrus precatorius (agglutinin), and Glycine max (soybean).

We have recently demonstrated that certain oligomannose and bisected hybrid type glycopeptides and bisected complex type oligosaccharides are bivalent for binding to concanavalin A and can precipitate the lectin [Bhattacharyya, L., Ceccarini, C., Lorenzoni, P., & Brewer, C.F. (1987) J. Biol. Chem. 262, 1288-1293; Bhattacharyya, L., Haraldsson, M., & Brewer, C.F. (1987) J. Biol. Chem. 262, 1294-1299]. The present results show that tri- and tetraantennary complex type oligosaccharides containing nonreducing terminal galactose residues, and a related triantennary glycopeptide, precipitate the D-galactose-specific lectins from Ricinus communis (agglutinin I) (RCA-I), Erythrina indica (EIL), Erythrina arborescens (EAL), and Glycine max (soybean) (SBA). Nonbisected and bisected biantennary complex type oligosaccharides can precipitate SBA, which is a tetrameric lectin, but not RCA-I, EIL, or EAL, which are dimeric lectins. The relative affinities of the oligosaccharides and glycopeptide were determined by hemagglutination inhibition measurements and their valencies by quantitative precipitin analyses. The equivalence points of the precipitin curves indicate that the tri- and tetraantennary oligosaccharides are tri- and tetravalent, respectively, for EIL, EAL, and SBA binding. However, the oligosaccharides are all trivalent for RCA-I binding due apparently to the larger size of the monomeric subunit of the lectin. The triantennary glycopeptide was also trivalent for RCA-I and EIL binding. Biantennary oligosaccharides with adequate chain lengths were found to be bivalent for binding to SBA; those with shorter chains did not precipitate the lectin.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Conformation↗
PubMed1988

Comparative structural study of N-linked oligosaccharides of urinary and recombinant erythropoietins.

The structures of the N-linked oligosaccharides of the urinary erythropoietin (u-EPO) purified from urine of aplastic anemic patients were analyzed and compared with those for recombinant erythropoietin (r-EPO) prepared with baby hamster kidney (BHK) cells. Asparagine-linked neutral oligosaccharides were released from each EPO protein by N-oligosaccharide glycopeptidase (almond) digestion. The reducing ends of the oligosaccharide chains thus obtained were aminated with a fluorescent reagent, 2-aminopyridine, and the mixture of pyridylamino derivatives of the oligosaccharides was separated by high-performance liquid chromatography (HPLC) on an ODS silica column. More than 8 and 13 kinds of oligosaccharide fractions for u-EPO and r-EPO (BHK), respectively, were completely separated by the one-step HPLC procedure. The structure of each oligosaccharide thus isolated was analyzed by a combination of sequential exoglycosidase digestion and another kind of HPLC with an amide-silica column. Furthermore, high-resolution proton nuclear magnetic resonance (1H NMR) spectroscopy and methylation analyses were carried out in the case of r-EPO (BHK).(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Sequence↗
PubMed1989

Structure of the major concanavalin A reactive oligosaccharides of the extracellular matrix component laminin.

Laminin, a high molecular weight (1,000,000) glycoprotein component of basement membranes, was isolated from the EHS murine tumor as a noncovalent complex with entactin by lectin affinity chromatography using the alpha-D-galactosyl binding lectin Griffonia simplicifolia I (GS I). Entactin was removed from this complex by passage over Sephacryl S-1000 in the presence of SDS. Compositional analysis showed that the affinity-purified laminin contained 25-30% carbohydrate by weight. Methylation analysis revealed that the oligosaccharides of laminin contained bi- and triantennary chains, the blood group I structure, and repeating sequences of 3Gal beta 1,4GlcNAc beta 1 units. Free oligosaccharides were derived from the asparagine-linked glycans of affinity-purified laminin by hydrazinolysis, re-N-acetylation, and reduction with NaB3H4. When fractionated by affinity chromatography on concanavalin A (Con A)-Sepharose, 80% of the oligosaccharides passed through the column unretarded and a single peak corresponding to 20% of the oligosaccharides was adsorbed and specifically eluted with a linear gradient of 0-30 mM methyl alpha-D-glucopyranoside. Further fractionation of the Con A reactive oligosaccharides on GS I-Sepharose demonstrated that 70% of these oligosaccharides possess at least one terminal nonreducing alpha-D-galactopyranosyl unit. The Con A reactive oligosaccharides were subjected to sequential digestion with endo- and exoglycosidases, and the reaction products were analyzed by gel filtration chromatography on a column of Bio-Gel P4. We thereby obtained evidence for a variety of structures not previously reported to exist on murine laminin including hybrid biantennary complex and biantennary complex structures containing poly(lactosaminyl) repeating units. The poly(lactosaminyl) units occur either on one or on both branches of the biantennary chains, as well as in more highly branched blood group I poly(lactosamine) structures. All sialic acid is present as N-acetylneuraminic acid linked alpha 2,3 to galactose.

Amino Acids↗