Resolution of nucleotide sugars and oligosaccharides by lectin affinity chromatography

Structure and Activity Changes of Phytohemagglutinin from Red Kidney Bean (Phaseolus vulgaris) Affected by Ultrahigh-Pressure Treatments

Phytohemagglutin (PHA), purified from red kidney beans (Phaseolus vulgaris) by Affi-Gel blue affinity chromatography, was subjected to ultrahigh-pressure (UHP) treatment (150, 250, 350, and 450 MPa). The purified PHA lost its hemagglutination activity after 450 MPa treatment and showed less pressure tolerance than crude PHA. However, the saccharide specificity and α-glucosidase inhibition activity of the purified PHA did not change much after UHP treatment. Electrophoresis staining by periodic acid-Schiff (PAS) manifested that the glycone structure of purified PHA remained stable even after 450 MPa pressure treatment. However, electrophoresis staining by Coomassie Blue as well as circular dichroism (CD) and differential scanning calorimetry (DSC) assay proved that the protein unit structure of purified PHA unfolded when treated at 0-250 MPa but reaggregates at 250-450 MPa. Therefore, the hemagglutination activity tends to be affected by the protein unit structure, while the stability of the glycone structure contributed to the remaining α-glucosidase inhibition activity.

Enzymatic analysis of uridine diphosphate N-acetyl-D-glucosamine

The Methanococcus maripaludis MMP0352 protein belongs to an oxidoreductase family that has been proposed to catalyze the NAD(+)-dependent oxidation of the 3'' position of uridine diphosphate N-acetyl-D-glucosamine (UDP-GlcNAc), forming a 3-hexulose sugar nucleotide. The heterologously expressed MMP0352 protein was purified and shown to efficiently catalyze UDP-GlcNAc oxidation, forming one NADH equivalent. This enzyme was used to develop a fixed endpoint fluorometric method to analyze UDP-GlcNAc. The enzyme is highly specific for this acetamido sugar nucleotide, and the procedure had a detection limit of 0.2 microM UDP-GlcNAc in a 1-ml sample. Using the method of standard addition, UDP-GlcNAc concentrations were measured in deproteinized extracts of Escherichia coli, Saccharomyces cerevisiae, and HeLa carcinoma cells. Equivalent concentrations were determined by both enzymatic and chromatographic analyses, validating this method. This procedure can be adapted for the high-throughput analysis of changes in cellular UDP-GlcNAc concentrations in time series experiments or inhibitor screens.

Vicia villosa B4 lectin inhibits nucleotide pyrophosphatase activity toward UDP-GalNAc specifically

Plant seed lectins play a defense role against plant-eating animals. Here, GalNAc-specific Vicia villosa B4 lectin was found to inhibit hydrolysis of UDP-GalNAc by animal nucleotide pyrophosphatases, which are suggested to regulate local levels of nucleotide sugars in cells. Inhibition was marked at low concentrations of UDP-GalNAc, and was reversed largely by the addition of GalNAc to the reaction mixture. In contrast, lectin inhibited enzymatic hydrolysis of other nucleotide sugars, such as UDP-Gal and UDP-GlcNAc, only to a small extent, and GalNAc did not affect such an inhibition. The binding constant of the lectin for UDP-GalNAc was as high as 2.8 x 10(5) M-1 at 4 degrees C, whereas that for GalNAcalpha-1-phosphate was 1.3 x 10(5) M-1. These findings indicate that lectin inhibition of pyrophosphatase activity toward low concentrations of UDP-GalNAc arises mainly from competition between lectin and enzyme molecules for UDP-GalNAc. This type of inhibition was also observed to a lesser extent with GalNAc-specific Wistaria floribunda lectin, but not apparently with GalNAc-specific soybean or Dolichos biflorus lectin. Thus, V. villosa B4 lectin shows unique binding specificity for UDP-GalNAc and has the capacity to modulate UDP-GalNAc metabolism in animal cells.

Differentiative changes in fucosyltransferase activity in newborn rat epidermal cells

An enzymatic activity catalyzing the transfer of L-fucose from GDP-L-fucose to a glycoprotein that is associated with the surfaces of the basal cells has been found in the membranous fraction of the cutaneous epidermis from the newborn rat. This fucosyltransferase which is located in the differentiated cells alters the acceptor glycoprotein's lectin-binding specificity from the Isolectin I-B4 of Griffonia simplicifolia (GS I-B4) to the Agglutinin I of Ulex europeus (UEA) and could be responsible for the same change in lectin-binding specificity that occurs as the epidermal basal cell differentiates. Another membraneous fucosyltransferase that can use asialofetuin--but not the GS I-B4-binding glycoprotein--as an acceptor, is also present in the membraneous fraction.

Transient hyperglycosylation of rhodopsin with galactose

Rhodopsin's oligosaccharide chains contain predominantly two types of sugar residues: mannose and N-acetylglucosamine. In the present work, bovine and rat rhodopsin were analysed biochemically for the presence of a third sugar, galactose. Treatment of bovine rod outer segments (ROS) with galactose oxidase followed by reduction with tritium-labeled sodium borohydride revealed the presence of existing molecules of galactose on rhodopsin. Rats injected intravitreally with [3H]galactose and [14C]leucine and maintained in darkness were killed 1 hr, 6 hr, 1, 3 or 5 days following the injection. Retinas were collected for subcellular fractionation and rhodopsin from each of the fractions was purified by ConA sepharose chromatography and SDS-PAGE. During the first 6 hr, galactose selectively labeled rhodopsin in the Golgi-enriched fraction resulting in increased [3H]/[14C] ratios in both Golgi and ROS. The data suggested that trimming was occurring at the transition from Golgi to ROS. Furthermore, a decrease in isotope ratio in the ROS between 6 hr and 1 day suggested further trimming of rhodopsin after membrane assembly in the ROS. Additional in vivo experiments demonstrated existing molecules of galactose on rhodopsin's oligosaccharide chain using lectin affinity chromatography. Rats injected intravitreally with [35S]methionine were dark-adapted for 2 hr. Following subcellular fractionation of retinas, ConA purified rhodopsin from ROS was applied to one of two additional lectin columns: Ricinus communis agglutinin (RCA) or Griffonia simplicifolia I (GSA). Eight to nine percent of the labeled rhodopsin was bound to and eluted from RCA, whereas none bound to GSA, indicating the presence of a beta-galactoside. The RCA agarose eluted protein co-electrophoresed with a rhodopsin standard and was light sensitive. Galactose was shown to be the terminal sugar on this subset of rhodopsin and was not capped by neuraminic acid. Binding of rhodopsin's oligosaccharide to RCA was abolished by pre-treatment with beta-galactosidase. Decreased binding of rhodopsin to RCA was observed following intravitreal injection of castanospermine but not swainsonine. Of those two inhibitors of glycoprotein trimming, only castanospermine would be expected to prevent the addition of galactose to the oligosaccharide. The association of galactose with rat rhodopsin appeared to be a transient one. At 2 hr, 8-9% of rhodopsin contained galactose, at 6 hr only 2.2% had galactose and by 24 hr less than 1% did. The galactose was trimmed from rhodopsin's oligosaccharide presumably after its role was complete. Separation of rhodopsin of the plasma membranes from rhodopsin of discs indicated that 75% of the galactose-containing rhodopsin was in the plasma membrane and only 25% was in the discs. These findings suggested a possible role for galactose in new disc formation with subsequent removal after the discs are sealed.

N-acetyllactosaminooligosaccharides that contain the beta-D-GlcpNAc-(1----6)-D-Gal or beta-D-GlcpNAc-(1----6)-D-GalNAc sequences reveal reduction-sensitive affinities for wheat germ agglutinin

Affinity chromatography of unreduced oligosaccharides on a small column of immobilized wheat germ agglutinin (WGA) revealed high-binding affinities for several radiolabeled molecules containing at the reducing end either beta-D-GlcpNAc-(1----6)-D-Gal, beta-D-GlcpNAc-(1----6)-beta- D-Galp-(1----4)-D-GlcNAc, beta-D-GlcpNAc-(1----6)-beta-D-Galp-(1----4)DGlc, D-GlcpNAc-(1----3)-[beta-D-GlcpNAc-(1----6)]-D-Gal, beta-D-GlcpNAc-(1----6)- D-GalNAc, or beta-D-Galp-(1----3)-[beta-D-GlcpNAc-(1----6)]-D-GalNAc sequences. Reduction changed the binding affinities remarkably: The sequences carrying a D-galactose or 2-acetamido-2-deoxy-D-galactose residue at the reducing end lost most of their affinities, but the sequences containing a D-glucose or 2-acetamido-2-deoxy-D-glucose residue at the reducing end gained additional affinity upon reduction. These findings emphasize the role of the unreduced, 6-o-substituted D-galactose and 2-acetamido-2-deoxy-D-galactose residues for the binding of saccharides to WGA, which has been recognized previously as a lectin specific for oligosaccharides containing a 2-acetamido-2-deoxy-D-glucose or sialic acid unit. The results suggested also that WGA-agarose chromatography of alditols may become a valuable method for the fractionation of oligo-N-acetyllactosaminoglycans and related saccharides.

N-linked oligosaccharide changes with oncogenic transformation require sialylation of multiantennae

Glycopeptides derived from NIH 3T3 fibroblasts and these cells transformed by transfection with human DNA containing oncogene H-ras were analyzed by 500-MHz 1H-NMR spectroscopy and binding to immobilized lectins. The cells were metabolically labeled with D-[3H]glucosamine or L-[3H]fucose and the glycopeptides included in Bio-Gel P-10 (Mr 5000-3500) were separated into neutral and charged fractions on DEAE-cellulose. The major portion (80%) of these [3H]fucose glycopeptides from the non-transformed NIH 3T3 fibroblasts were neutral or contained one or two charged residues, whereas 90% of the glycopeptides from the transformed cells contained two or more charged residues. The structure of the predominant neutral glycopeptide from the non-transformed NIH 3T3 cells was determined by 1H-NMR spectroscopy to be tetraantennary containing terminal Gal alpha 1----3. (formula; see text) This structure was verified by binding to the immobilized alpha-Gal-specific lectin, Griffonia simplicifolia I and leukoagglutinating phytohemagglutinin from Phaseolus vulgaris (L-PHA), which binds certain tri- or tetraantennary glycopeptides. In contrast, the structure derived by NMR spectroscopy of one of the predominant charged glycopeptides from the transformed cells was triantennary containing terminal NeuNAc alpha 2----3 in addition to Gal alpha 1----3. (formula; see text) In attempting to verify this structure by lectin-binding properties it was found that removal of NeuNAc alpha 2----3 reduced the affinity to L-PHA - agarose. The other major glycopeptides of the transformed cells which were more charged also cotained NeuNAc alpha 2----3 but no NeuNAc alpha 2----6 or Gal alpha 1----3. A tentative structure was proposed for the major glycopeptide of the first charged class from NIH 3T3 cells on the basis of lectin-binding properties and the NMR spectrum which showed, in addition to NeuNAc alpha 2----3, the presence of NeuNAc alpha 2----6 and Gal alpha 1----3. On the basis of the NMR spectrum and other results, it is concluded that the presence of tetraantennary oligosaccharides are not sufficient for the transformed oligosaccharide phenotype. Rather, the tri- or tetraantennae must be sialylated in alpha 2----3 linkage, on more than one antennae, when properties of transformation are expressed in NIH 3T3 cells. Prior to transformation the tetraantennary oligosaccharides of these cells are terminated in alpha-Gal residues, whereas after transformation alpha-Gal residues appear to be replaced by NeuNAc alpha 2----3.(ABSTRACT TRUNCATED AT 400 WORDS)

The linear tetrasaccharide, Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4GlcNAc, isolated from radiolabeled teratocarcinoma poly-N-acetyllactosaminoglycan resists the action of E. freundii endo-beta-galactosidase

A novel linear tetrasaccharide, Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4GlcNAc, 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 GlcNAc beta 1-6Gal beta 1-4GlcNAc, resisted the action of endo-beta-galactosidase (EC 3.2.1.103) from E. freundii at a concentration of 125 mU/ml, while the isomeric, radioactive teratocarcinoma saccharides Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc and GlcNAc beta 1-3Gal beta 1-4GlcNAc were cleaved in the expected manner.

Interaction of asparagine-linked oligosaccharides with an immobilized rice (Oryza sativa) lectin column

The carbohydrate-binding specificity of rice (Oryza sativa) lectin was investigated by testing the ability of radioactively labelled glycopeptides and oligosaccharides to bind to a rice lectin-Sepharose 4B column. Rice lectin binds asparagine-linked oligosaccharides through the core NN'-diacetylchitobiose moiety. Whereas beta 1-4-mannose enhances the binding strength only to a small extent, alpha 1-3-linked core mannose increases it considerably. A core alpha 1-6-linked mannose residue has a slightly inhibitory effect. Binding is not affected when one or both of the alpha-mannose residues are substituted with mannose at C-2, C-3 and C-6 or with N-acetylglucosamine (GlcNAc) at C-2 positions. The presence of an alpha 1-6-fucose residue attached to the asparagine-linked GlcNAc also does not affect the binding. The binding of complex biantennary glycopeptides is not altered by the presence of one or two galactose residues in the non-reducing terminus, but the presence of one or two sialic acid residues decreases the binding capacity. A bisecting beta 1-4-linked GlcNAc attached to beta-linked mannose residue enhances the binding of sialo, asialo and asialoagalacto complex biantennary-type glycopeptides. Bisected hybrid-type glycopeptides bind very tightly to a rice lectin-Sepharose 4B column: Substitution of alpha 1-3-mannose residue at C-2 and C-4 with GlcNAc completely inhibits the binding of both bisected and non-bisected complex asparagine-linked glycopeptides. O-Glycosidically linked oligosaccharides containing GlcNAc bind very weakly to a rice lectin column. The applicability of immobilized rice lectin columns in the fractionation of asparagine-linked oligosaccharides is discussed.

Occurrence in Bacillus megaterium of uridine 5'-diphospho-N-acetylgalactosamine and uridine 5'-diphosphogalactosamine, intermediates in the biosynthesis of galactosamine-6-phosphate polymer

We isolated two galactosamine derivatives from Bacillus megaterium sporulating cells by lectin affinity chromatography followed by DEAE-Sephadex A-25 chromatography. From chemical analyses and measurements of these compounds, it was determined that one was uridine 5'-diphospho-N-acetylgalactosamine and that the other was uridine 5'-diphosphogalactosamine. They appeared in the middle stage of sporulation and disappeared during the period when galactosamine-6-phosphate is deposited on the forespore surface. These results suggest that uridine 5'-diphospho-N-acetylgalactosamine and uridine 5'-diphosphogalactosamine are intermediates in the biosynthesis of the galactosamine-6-phosphate polymer, a backbone structure of the exosporium.

Glycoproteins of human teratocarcinoma cells (PA1) carry both anomers of O-glycosyl-linked D-galactopyranosyl-(1----3)-2-acetamido- 2-deoxy-alpha-D-galactopyranosyl group

Two disaccharide alcohols, alpha-D-Galp(1----3)-GalNAcol and beta-D-Galp-(1----3)-GalNAcol, together with a GalNAcol-containing tetra- or penta-saccharide alcohol, were released from human embryonal carcinoma cells of line PA1 by reductive beta-elimination. The disaccharides were identified by exoglycosidase digestions and by periodate oxidation. The results were confirmed by affinity chromatography of the disaccharide alcohols on immobilized Bandeirea simplicifolia lectin and by chromatography of the parent glycopeptides on immobilized peanut lectin.

Isolation and characterization of a wheat germ agglutinin-binding glycoprotein from B16 mouse melanoma cells

Cells of B16 mouse melanoma grown in serum-free medium in the presence of [3H]glucosamine secreted or shed labeled glycoproteins. A wheat germ agglutinin-binding glycoprotein was isolated that accounted for 37% of the total [3H]glucosamine incorporated; it had a molecular weight of approximately 50,000 and was absent in less-tumorgenic wheat germ agglutinin (isolectin I)-resistant variants of the cells. The glycoprotein contained approximately 25% of serine and threonine plus equimolar amounts of glucosamine and galactosamine, indicating both N- and O-linked oligosaccharide chains. Neuraminidase treatment released approximately 60% of the glycoprotein's 3H radioactivity as N-acetylneuraminic acid. The sialoglycoprotein did not, but the desialylated species did, bind (97%) to ricin-Sepharose, suggesting the presence of terminal sialic acid and penultimate galactose residues in most of the saccharide units. Alkaline borohydride released 61% of the glycoprotein's radioactivity as oligosaccharide alcohols that were mainly tetrasaccharides (75%) with some branched trisaccharides (10%) from the O-linked structures. Hydrazinolysis and analysis of the alkaline borohydride-resistant portion of the glycoprotein indicated the presence of mainly triantennary, complex-type structures (N-linked) containing three sialic acids residues plus L-fucose. Serial lectin-affinity chromatography of the hydrazine-released saccharides with concanavalin A-agarose, pea lectin-agarose, L-PHA-agarose, and E-PHA-agarose, indicated the absence of high-mannose or hybrid-type structures and further confirmed the presence of triantennary, complex-type units.

Separation and analysis of 4'-epimeric UDP-sugars by borate high-performance liquid chromatography

Separation of UDP-glucose from UDP-galactose, of UDP-N-acetylglucosamine from UDP-N-acetylgalactosamine, of UDP-glucuronate from UDP-galacturonate, or of UDP-glucosamine from UDP-galactosamine was achieved within 10-45 min by isocratic anion-exchange high-performance liquid chromatography (HPLC) using a flow rate of 2 ml/min. The eluants were composed of borate as complex-forming and eluting agent and of glycerol for protection of the alkali-labile silica packing of the column. This borate HPLC was suitable for the analysis of 4'-epimeric UDP-sugars in the range of 2 to 100 nmol. The applicability of this technique was demonstrated by determination of the relative amounts of 4'-epimeric UDP-amino sugars formed in rat liver after administration of D-galactosamine. Since a high salt content of UDP-sugar samples can interfere with borate HPLC, desalting was performed on a 1-ml C18 cartridge using triethylammonium hydrogen carbonate buffer. This procedure enabled the complete separation of various nucleotides from salts within 10 min prior to HPLC.

Modification of cell surface glycoprotein: addition of fucosyl residues during epidermal differentiation

When cutaneous sections from the newborn rat were treated with alpha-fucosidase, Ulex europeus agglutinin I (UEA) binding to the cell surface of the differentiated cells in the epidermis was diminished and there was an appearance in these cell layers of binding by Bandeiraea simplicifolia I-B4 lectin (BS I-B4), which normally is specific for the basal cells. A similar treatment with alpha-galactosidase resulted in a loss of BS I-B4 binding, but had no effect on UEA binding. Glycoproteins isolated from the membranes of epidermal cells showed a threefold increase in the ratio of binding to UEA versus BS I-B4 affinity columns as the proteins were derived from the more differentiated cell populations. These data suggest that alpha-fucosyl residues are added to the glycoproteins on the cell surfaces of differentiated cells, thus blocking alpha-galactosyl residues and changing the lectin binding specificity as epidermal cells move out of the basal cell layer.