Single mid-chain GlcNAcβ1-6Galβ1-4R sequences of linear oligosaccharides are resistant to endo-β-galactosidase ofBacteroides fragilis

Endo--galactosidase (EC 3.2.1.103) ofBacteroides fragilis, at 250 mU ml^–1, did not cleave the internal galactosidic linkage of the linear radiolabelled trisaccharide GlcNAc1-6Gal1-4GlcNAc, or those of the tetrasaccharides Gal1-4GlcNAc1-6Gal1-4GlcNAc and Gal1-4GlcNAc1-6Gal1-4Glc. The isomeric glycans which contained the GlcNAc1-3Gal1-4GlcNAc/Glc sequence were readily cleaved.Abbreviations GlcNAc 2-acetamido-2-deoxy-d-glucose - Lact lactose - MT maltotriose - MTet maltotetraose - R _MTet chromatographic migration rate in relation to that of maltotetraose     

Light and electron microscopic detection of (3 Gal β1,4 GlcNAc β1) sequences in asparagine-linked oligosaccharides with the Datura stramonium lectin

Summary The Datura stramonium lectin recognizes with high affinity the disaccharide N-acetyllactosamine (Gal 1,4 GlcNAc). We have developed a highly specific cytochemical affinity technique in which an ovomucoid-gold complex serves as second step reagent for the visualization of this lectin bound to reactive sequences present in tissue sections. The lectin binding sites were detected in semithin and ultrathin sections of aldehyde-fixed and low temperature Lowicryl K4M embedded tissues. For light microscopical labeling the photochemical silver reaction for signal amplification was required. The application of this technique for the detection of N-acetyllactosamine containing asparagine-linked oligosaccharides in various intracellular organelles and the plasma membrane is demonstrated.This study was supported by the Swiss National Science Foundation grant nr. 31-26273.89 (to J.R.) and GM 29470 from the National Institutes of Health (to I.J.G.). Dr. G. Egea was a recipient of a European Molecular Biology Organization long term fellowship.     

H NMR analysis of novel sialylated and fucosylated lactose-based oligosaccharides having linear GlcNAc(β1–6)Gal and Neu5Ac(α2–6)GlcNAc sequences

Three novel oligosaccharides of human infant faeces have been fully characterised by methylation analysis and 500/600 MHz ¹H NMR spectroscopy including DQF-COSY, TQF-COSY, TOCSY and ROESY experiments. The oligosaccharides were shown to be lactose-based structures two of which were substituted at C-6 of Gal with either the Le^x trisaccharide, Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1-, or Neu5Ac(α2–6)Gal(β1–4)GlcNAc-(β1-. They differ from other free oligosaccharides previously isolated from the human by having the (1 → 6) linkage to Gal in the absence of a (1 → 3) branch. The third oligosaccharide has Neu5Ac(α2–6) linked to GlcNAc of the trisaccharide GlcNAc(β1–3)Gal(β1–4)Glc. This is a linear fragment of the disialylated tetrasaccharide sequence Neu5Ac(α2–3)Gal(β1–3)[Neu5Ac(α2–6)]GlcNAc(β1- found in the milk oligosaccharide disialyl LNT (the GlcNAc residue of the tetrasaccharide linked to lactose) and also of N-linked chains (GlcNAc linked to Man).     

UDP-GlcNAc: Galβ3GalNAc-Mucin: (GlcNAc → GalNAc) β6-N-Acetylglucosaminyltransferase and UDP-GlcNAc: Galβ3(GlcNAcβ6) GalNAc-Mucin (GlcNAc → Gal)β3-N-Acetylglucosaminyltransferase from Swine Trachea Epithelium

Summary Two specific -N-acetylglucosaminyltransferases involved in the branching and elongation of mucin oligosaccharide chains, namely, a 1,6 N-acetylglucosaminylsaminyltransferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal3GalNAc-Mucin to yield Gal3(GlcNAc6)GalNAc-Mucin and a 3-N-acetylglucosaminyl transferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal3(GlcNAC6)GalNAc-mucin to yield GlcNAc3Gal3 (GlcNAc6)GalNAc-Mucin were purified from the microsomal fraction of swine trachea epithelium. The 1,6-N-acetylglucosaminyltransferase was purified about 21,800-fold by procedures which included affinity chromatography on DEAE columns containing bound asialo Cowper's gland mucin glycoprotein with Gal1,3GalNAc side chains. The apparent molecular weight estimated by gel filtration was found to be about 60 Kd. The purified enzyme showed a high specificity for Gal1,3GalNAc chains and the most active substrates were mucin glycoproteins containing these chains. The apparent Km of the 6-glucosaminyltrans-ferase for Cowper's gland mucin glycoprotein containing Gal1,3GalNAc chains was 0.53 µM; for UDP-N-acetylglucosamine, 12 µM; and for Gal 1,3GalNAc NO₂ø, 4 mM. The activity of the 6-glucosaminyltransferase was dependent on the extent of glycosylation of the Gal3GalNAc chains in Cowper's gland mucin glycoprotein.The best substrate for the partially purified 3-Glucosaminyltransferase was Cowper's gland mucin glycoprotein containing Gal1,3(GlcNAc6)GalNAc side chains. This enzyme showed little or no activity with intact sialylated Cowper's gland mucin glycoprotein or derivatives of this glycoprotein containing GalNAc or Gal1,3GalNAc side chains.The radioactive oligosaccharides formed by these enzymes in large scale reaction mixtures were released from the mucin glycoproteins by treatment with alkaline borohydride, isolated by gel filtration on Bio-Gel P-6 and characterized by methylation analysis and sequential digestion with exoglycosidases. The oligosaccharide products formed by the 6- and 3-glucosaminyltransferases were shown to be Gal3(GlcNAC6) GalNAc and GlcNAc3 Gal3(GlcNAC6)GalNAc respectively.Taken collectively, these results demonstrate that swine trachea epithelium contains two specific N-acetylglucosaminyltransferases which catalyze the initial branching and elongation reactions involved in the synthesis of O-linked oligosaccharide chains in respiratory mucin glycoproteins. The first enzyme a 6-glucosaminyltransferase converts Gal3GalNAc chains in mucin glycoproteins to Gal3(GlcNAc6)GalNAc chains. This product is the substrate for a second 3-glucosaminyltransferase which converts the Gal3(GlcNAc6)GalNAc chains to GlcNAc3Gal(GlcNAc6)GalNAc chains in the glycoprotein. The 3-glucosaminyltransferase did not utilize Gal3GalNAc chains as a substrate and this results in an ordered sequence of addition of N-acetylglucosamine residues to growing oligosaccharide chains in tracheal mucin glycoproteins.Abbreviations NeuNAc N-acetylneuraminic acid - GalNAcol N-acetylgalactosaminitol - CGMG Cowper's gland mucin glycoprotein - GalNAc-CGMG Cowper's gland mucin glycoprotein containing GalNAc side chains O-glycosidically linked to serine or threonine - Gal3GalNAc-CGMC Cowper's gland mucin glycoprotein containing Gal3GalNAc side chains - MES 2-(N-morpholino) Ethane Sulfonic acid - PBS Phosphate Buffered Saline     

Synthesis of Galβ1-3GlcNAc and Galβ1-3GlcNAcβ-SEt by an enzymatic method comprising the sequential use of β-galactosidases from bovine testes andEscherichia coli

Gal1-3GlcNAc (1) and Gal1-3GlcNAc-SEt (2) were synthesized on a 100 mg scale by the transgalactosylation reaction of bovine testes -galactosidase with lactose as donor andN-acetylglucosamine and GlcNAc-SEt as acceptors. In both cases the product mixtures contained unwanted isomers and were treated with -galactosidase fromEscherichia coli which has a different specificity, under conditions favouring hydrolysis, yielding besides the desired products, monosaccharides and traces of trisaccharides. The products were purified to >95% by gel filtration, with a final yield of 12% of 1 and 17% of 2, based on added acceptor. In a separate experiment Gal1-6GlcNAc-SEt (3) was synthesized by the transglycosylation reaction using -galactosidase fromEscherichia coli. No other isomers were detected. Compound 3 was purified by HPLC.     

Synthesis of Galβ1-4GlcNAcβ- and Galβ1-3GalNAcα-O-L-serine Derivatives employing glycosidases

A new approach for the highly specific preparation of L-serine conjugates of lactosamine and Gal1-3GalNAc is described. Thus, the L-serine derivative of lactosamine Gal1-4GlcNAc-O-(N-Z)-Ser-OEt, was obtained from lactose, employing GlcNAc-O-(N-Z)-Ser-OEt as acceptor and a yeast -galactosidase as catalyst Galp 1-3GalNAc-O-(N-Alloc)-Ser-OMe was obtained from lactose, employing GalNAc-O-(N-Alloc)-Ser-OMe as acceptor and -galactosidase from bovine testes as catalyst.     

ProcessingO-glycan core 1, Galβ1-3GalNAcα-R. Specificities of core 2, UDP-GlcNAc: Galβ1-3GalNAc-R(GlcNAc to GalNAc) β6-N-acetylglucosaminyltransferase and CMP-sialic acid:Galβ1-3GalNAc-R α3-sialyltransferase

To elucidate control mechanisms ofO-glycan biosynthesis in leukemia and to develop biosynthetic inhibitors we have characterized core 2 UDP-GlcNAc:Gal1-3GalNAc-R(GlcNAc to GalNAc) 6-N-acetylglucosaminyl-transferase (EC 2.4.1.102; core 2 6-GlcNAc-T) and CMP-sialic acid: Gal1-3GalNAc-R 3-sialyltransferase (EC 2.4.99.4; 3-SA-T), two enzymes that are significantly increased in patients with chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML). We observed distinct tissue-specific kinetic differences for the core 2 6-GlcNAc-T activity; core 2 6-GlcNAc-T from mucin secreting tissue (named core 2 6-GlcNAc-T M) is accompanied by activities that synthesize core 4 [GlcNAc1-6(GlcNAc1-3)GalNAc-R] and blood group I [GlcNAc1-6(GlcNAc1-3)Gal-R] branches; core 2 6-GlcNAc-T in leukemic cells (named core 2 -GlcNAc-T L) is not accompanied by these two activities and has a more restricted specificity. Core 2 6-GlcNAc-T M and L both have an absolute requirement for the 4- and 6-hydroxyls ofN-acetylgalactosamine and the 6-hydroxyl of galactose of the Gal1-3GalNAc-benzyl substrate but the recognition of other substituents of the sugar rings varies, depending on the tissue. 3-sialytransferase from human placenta and from AML cells also showed distinct specificity differences, although the enzymes from both tissues have an absolute requirement for the 3-hydroxyl of the galactose residue of Gal1-3GalNAc-Bn. Gal1-3(6-deoxy)GalNAc-Bn and 3-deoxy-Gal1-3GalNAc-Bn competitively inhibited core 2 6-GlcNAc-T and 3-sialyltransferase activities, respectively.Abbreviations AFGP antifreeze glycoprotein - AML acute myeloid leukemia - Bn benzyl - CML chronic myelogenous leukemia - Fuc l-fucose - Gal, G d-galactose - GalNAc, GA N-acetyl-d-galactosamine - GlcNAc, Gn N-acetyl-d-glucosamine - HC human colonic homogenate - HO hen oviduct microsomes - HPLC high performance liquid chromatography - mco 8-methoxycarbonyl-octy - Me methyl - MES 2-(N-morpholino)ethanesulfonate - MK mouse kidney homogenate - onp o-nitrophenyl - PG pig gastric mucosal microsomes - pnp p-nitrophenyl - RC rat colonic mucosal microsomes - SA sialic acid - T transferase Enzymes: UDP-GlcNAc:Gal1-3GalNAc-R (GlcNAc to GalNAc) 6-N-acetylglucosaminyltransferase,O-glycan core 2 6-GlcNAc-transferase, EC 2.4.1.102; CMP-sialic acid: Gal1-3GalNAc-R 3-sialyltransferase,O-glycan 3-sialic acid-transferase, EC 2.4.99.4.     

The linear tetrasaccharide,Galβ1-4GlcNAcβ1-6Galβ1-4GlcNAc,isolated from radiolabeled teratocarcinoma poly-N-acetyllactosaminoglycan resists the action ofE. freundii endo-β-galactosidase

A novel linear tetrasaccharide, Gal1-4GlcNAc1-6Gal1-4GlcNAc, was isolated from partial acid hydrolysates of metabolically labeled poly-N-acetyllactosaminoglycans of murine teratocarcinoma cells. It was characterized by exo-glycosidase sequencing and by mild acid hydrolysis followed by identification of all partial cleavage products. The tetrasaccharide, and likewise labelled GlcNAc1-6Gal1-4GlcNAc, resisted the action of endo--galactosidase (EC 3.2.1.103) fromE. freundii at a concentration of 125 mU/ml, while the isomeric, radioactive teratocarcinoma saccharides Gal1-4GlcNAc1-3Gal1-4GlcNAc and GlcNAc1-3Gal1-4GlcNAc were cleaved in the expected manner.Abbreviations WGA wheat germ agglutinin - BSA bovine serum albumin - [³H]GlcNAc1-4-GlcNAc1-4GlcNAcOL N,N,NN'-triacetylchitotriose reduced with NaB³H₄     

Enzymatic syntheses of GlcNAcβ1-2Man and Galβ1-4GlcNAcβ1-2Man as components of complex type sugar chains

GlcNAc1-2Man and GlcNAc1-6Man were synthesized using the reverse hydrolysis activity of -N-acetylglucosaminidase from both jack beans and Bacillus circulans. In turn, Gal1-4GlcNAc1-2Man and Gal1-4GlcNAc1-6Man were synthesized regioselectively using the transglycosylation activity of -galactosidase from Diplococcus pneumoniae and B. circulans, respectively. These di- and trisaccharides are important components of complex type sugar chains and will be used as intermediates in our synthetic studies. Abbreviations: pNp--GlcNAc, p-nitrophenyl 2-acetamido-2-deoxy--D-glucopyranoside; pNp--Gal, p-nitrophenyl -D-galacto-pyranoside     

Action of rat liver Galβ1-4GlcNAc α(2-6)-sialyltransferase on Manβ1-4GlcNAcβ-OMe,GalNAcβ1-4GlcNAcβ-OMe,Glcβ1-4GlcNAcβ-OMe and GlcNAcβ1-4GlcNAcβ-OMe as synthetic substrates

Incubation of synthetic Man\1-4GlcNAc-OMe, GalNAc1-4GlcNAc-OMe, Glc1-4GlcNAc-OMe, and GlcNAc1-4GlcNac-OMe with CMP-Neu5Ac and rat liver Gal1-4GlcNAc (2-6)-sialyltransferase resulted in the formation of Neu5Ac2-6Man1-4GlcNAc-OMe, Neu5Ac2-6GalNAc1-4GlcNAc-OMe, Neu5Ac2-6Glc1-4GlcNAc-OMe and Neu5Ac2-6GlcNAc1-4GlcNAc-OMe, respectively. Under conditions which led to quantitative conversion of Gal1-4GlcNAc-OEt into Neu5Ac2-6Gal1-4GlcNAc-OEt, the aforementioned products were obtained in yields of 4%, 48%, 16% and 8%, respectively. HPLC on Partisil 10 SAX was used to isolate the various sialyltrisaccharides, and identification was carried out using 1- and 2-dimensional 500-MHz¹H-NMR spectroscopy.Abbreviations 2D 2-dimensional - CMP cytidine 5-monophosphate - CMP-Neu5Ac cytidine 5-monophospho--N-acetylneuraminic acid - COSY correlation spectroscopy - DQF double quantum filtered - HOHAHA homonuclear Hartmann-Hahn - MLEV composite pulse devised by M. Levitt - Neu5Ac N-acetylneuraminic acid - Neu5Ac2en 2-deoxy-2,3-didehydro-N-acetylneuraminic acid     

Comparison of two β-glucosidases for the enzymatic synthesis of β-(1-6)-β-(1-3)-gluco-oligosaccharides

A domain of epiglucan was synthesized by beta-glucosidases. Two beta-glucosidases, an extracellular beta-glucosidase derived from Sclerotinia sclerotiorum grown on xylose, and a commercial lyophilized preparation of beta-glucosidase from Aspergillus niger, were used to synthesize gluco-oligosaccharides from cellobiose and, specially, beta-(1-6) branched beta-(1-3) gluco-oligosaccharides, corresponding to the structure of epiglucan. Gentiobiose, cellotriose, cellotetraose, beta-Glc-(1-3)-beta-Glc-(1-4)-Glc, beta-Glc-(1-6)-beta-Glc-(1-4)-Glc and beta-Glc-(1-6)-beta-Glc-(1-3)-Glc were synthesized from cellobiose by both enzymes. The latter compound was preferentially synthesized by the beta-glycosidase from Sclerotinia sclerotiorum. Under the best conditions, only 7 g l(-1) of beta-Glc-(1-6)-beta-Glc-(1-3)-Glc was synthesized by the beta-glycosidase from Aspergillus niger compared to 20 g l(-1) synthesized with beta-glycosidase from Sclerotinia sclerotiorum.     

Synthesis of Gal-β-(1→4)-GlcNAc-β-(1→6)-[Gal-β- (1→3)]-GalNAc-α-OBn oligosaccharides bearing O-methyl or O-sulfo groups at C-3 of the Gal residue: specific acceptors for Gal: 3-O-sulfotransferases

Our recent studies have revealed the existence of two distinct Gal: 3-O-sulfotransferases capable of acting on the C-3 position of galactose in a Core 2 branched structure, e.g., Gal14GlcNAc16(Gal13)GalNac1OBenzyl as acceptor to give 3-O-sulfoGal14GlcNAc13(Gal13)GalNAc1OB 20 and Gal14GlcNAc16(3-O-sulfoGal13)GalNAc1OB 23. We herein report the synthesis of these two compounds and also that of other modified analogs that are highly specific acceptors for the two sulfotransferases. Appropriately protected 1-thio-glycosides 7, 8, and 10 were employed as glycosyl donors for the synthesis of our target compounds.     

Probe design and synthesis of Galβ(1→3)[NeuAcα(2→6)]GlcNAcβ(1→2)Man motif of N-glycan

Synthesis and clusterization of Galβ(1→3)[NeuAcα(2→6)]GlcNAcβ(1→2)Man motif of the N-glycan, as the molecular probes for their biological evaluation, are reported. Key step is the quantitative and the completely α-selective sialylation of the C5-azide N-phenyltrifluoroacetimidate with the disaccharide acceptor, Galβ(1→3)GlcNTroc. Clusterization of the 16 molecules of trisaccharide motif was also achieved by the ‘self-activating click reaction’. These probes could efficiently be labeled by biotin and/or other fluorescence- or radioactive reporter groups through either cross metathesis, acylation, Cu(I)-mediated Huisgen [2+3]-cycloaddition, or the azaelectrocyclization to utilize the various biological techniques.     

Identification of a GDP-Fuc:Galβ1–3GalNAc-R (Fuc to Gal)α1–2 fucosyltransferase and a GDP-Fuc:Galβ1–4GlcNAc (Fuc to GlcNAc)α1–3 fucosyltransferase in connective tissue of the snailLymnaea stagnalis

Connective tissue of the freshwater pulmonateLymnaea stagnalis was shown to contain fucosyltransferase activity capable of transferring fucose from GDP-Fuc in 1–2 linkage to terminal Gal of type 3 (Gal1–3GalNAc) acceptors, and in 1–3 linkage to GlcNAc of type 2 (Gal1–4GlcNAc) acceptors. The 1–2 fucosyltransferase was active with Gal1–3GalNAc1-OCH₂CH=CH₂ (K _m=12 mM,V _max=1.3 mU ml^–1) and Gal1–3GalNAc (K _m=20 mM,V _max=2.1 mU ml^–1), whereas the 1–3 fucosyltransferase was active with Gal1–4GlcNAc (K _m=23 mM,V _max=1.1 mU ml^–1). The products formed from Gal1–3GalNAc1-OCH₂CH=CH₂ and Gal1–4GlcNAc were purified by high performance liquid chromatography, and identified by 500 MHz¹H-NMR spectroscopy and methylation analysis to be Fuc1–2Gal1–3GalNAc1-OCH₂CH=CH₂ and Gal1–4(Fuc1–3)GlcNAc, respectively. Competition experiments suggest that the two fucosyltransferase activities are due to two distinct enzymes.Abbreviations 2Fuc-T 1–2 fucosyltransferase - 3Fuc-T 1–3 fucosyltransferase - MeO-3Man 3-O-methyl-D-mannose - MeO-3Gal 3-O-methyl-D-galactose     

Bi-antennary oligo-(N-acetyllactosamino)glycans of I-type are galactosylated preferentially at the GlcNAcβ1-6Gal linked arms by α1,3-galactosyltransferase of bovine thymus

1,3-Galactosylation of radiolabelled bi-antennary acceptors Gal1-4GlcNAc1-3(Gal1-4GlcNAc1-6)Gal-R (R=1-OH, 1-4GlcNAc or 1-4Glc) with bovine thymus 1,3-galactosyltransferase was studied. At all stages of the reactions the three acceptors reacted faster at the 1 6 linked arm than at the 1 3 linked branch. Hence, in addition to the doubly 1,3-galactosylated products, practically pure Gal1-4GlcNAc1-3(Gal1-3Gal1-4GlcNAc1-6)Gal-R could be obtained from the three acceptors in reactions that had proceeded to near completion. The isomeric mono-1,3-galactosylated products were identified by using exoglycosidases to remove the branches unprotected by 1,3-galactoses and by subsequently identifying the resulting linear glycans chromatographically.Abbreviations Gal d-galactose - GlcNAc N-acetyl-d-glucosamine - Lac lactose - LacNAc Gal1-4GlcNAc - MH maltoheptaose - MP maltopentaose - MT maltotriose - MTet maltotetraose - WGA wheat germ agglutinin - 3 position 3 of the galactose unit of LacNAc or Lac - 6 position 6 of the galactose unit of LacNAc or Lac     

Linkage analysis of (1→6)-linked oligosaccharides by alkaline degradation

2-C-Methylglyceric acid was formed by sequential degradation of the chain in isomaltose oligosaccharides in aqueous barium hydroxide. The products of the stopping reaction, namely 6-O-substituted 3-deoxy-d-hexonic acids, were also obtained in considerable yield. The separation and determination of these products is of importance for the analysis of the linkage sequence in oligosaccharides.     

Glycoconjugates with Neu5Ac(α2,6)Gal(β1,4)GlcNAc sequences: a selective lectin-histochemical property of Kurloff cells in guinea pig thymus

Summary The Kurloff cell (KC), a natural killer lymphocyte, contains a large (10-m diameter) periodic acid-Schiff (PAS)-positive lysosome-like inclusion body called the Kurloff body (KB), which exhibits strong acid phosphatase activity. The presence of Sambucus nigra agglutinin (SNA)-reactive Neu5Ac(2,6)-D-Gal/Gal-NAc(1,4)GlcNAc oligosaccharide sequences and the absence of the corresponding Neu5Ac(2,3) Maackia amurensis agglutinin (MAA)-reactive sequence in the major 35-kDa N-glycosylproteins of the complex or hybrid type extracted from purified KC were established by Western-lectin-blotting of cytosolic extracts from purified KC. Moreover, these SNA-reactive sequences, or at least part of them, were shown to be borne by sialidase-sensitive KC acid isophosphatases. Thymic sections rich in KC, from estrogenized guinea pigs were examined by affino-histochemistry with these sialic acid-reactive lectins. The SNA-reactivity of thymic sections was quasiexclusively confined to KC clusters, whereas the whole thymic section was negative for MAA. KC were not SNA-reactive following preincubation and incubation with 200 mM lactose. When submitted to enzymatic or mild chemical desialylation processes, the SNA-reactivity of the KC clusters was enhanced. The SNA-reactivity of KC clusters was completely abolished following prolonged chemical desialylation, whereas the PAS-positivity of KB remained unchanged. Even after a prolonged sialidase treatment, this SNA-reactivity was only reduced. Moreover, after both these desialylation processes, KC developed a heavier Ricinus communis agglutinin-reactivity, thus confirming the presence of penultimate Gal residues in their abundant SNA-reactive oligosaccharide sequences Neu5Ac(2,6)Gal(1,4)GlcNAc. Such a selective lectin histochemical property provides a marker for detecting KC.     

Oligo-N-acetyllactosaminoglycans bearing Galβ1-4(Fucα1-3)GlcNAc sequences reveal lower affinities than their nonfucosylated,or α(1-2) fucosylated counterparts for immobilized wheat germ agglutinin

Relative affinities of several fucosylated and nonfucosylated oligo-N-acetyllactosaminoglycans for immobilized wheat germ agglutinin (WGA) were studied using a chromatographic technique. (1-3) Fucosylation of theN-acetylglucosamine unit(s) in mono- and biantennary saccharides of the Gal1-4GlcNAc-R type strongly reduced the WGA-affinity. In contrast, (1-2) fucosylation of the nonreducing galactose unit(s) of the saccharides did not reduce the affinity.     

The α-Gal epitope (Galα1-3Galβ1-4GlcNAc-R) in xenotransplantation

Many patients with failing organs (e.g., heart, liver or kidneys), do not receive the needed organ because of an insufficient number of organ donors. Pig xenografts have been considered as an alternative source of organs for transplantation. The major obstacle currently known to prevent pig to human xenotransplantation is the interaction between the human natural anti-Gal antibody and the alpha-gal epitope (Gal alpha 1-3Gal beta 1-4GlcNAc-R), abundantly expressed on pig cells. This short review describes the characteristics of anti-Gal and of the alpha-gal epitope, their role in inducing xenograft rejection and some experimental approaches for preventing this rejection.