Interactions of sulfated mucopolysaccharides with lectins. Application to the separation of mucopolysaccharide mixtures

Quantitative determination of individual glycosaminoglycans in plasma by concanavalin A rocket electrophoresis

A new one-dimensional agarose gel electrophoresis method for the quantitation of glycosaminoglycans in biological samples has been described. In this procedure, concanavalin A, suspended in agarose gel, interacts with glycosaminoglycans such that rocket-like precipitin lines are formed. The area of the rocket is directly proportional to the glycosaminoglycan content of the sample. This procedure permits measurement of glycosaminoglycans in amounts as low as 0.5 nmol uronic acid equivalents with a coefficient of variation of only 8%. The described method has been applied to the determination of free heparan sulfate in plasma. This method can also be used to measure all high-charge glycosaminoglycans of biological interest.

The interaction of mouse myeloma immunoglobulin S15 with negatively charged polysaccharide antigens

A murine BALB/c IgG2a (lambda 3) myeloma immunoglobulin SAPC-15 with binding activity for negatively charged polysaccharides has been purified by affinity chromatography, and its interaction with heparin and various other polyanionic antigens has been studied. The antigen-binding activity has been demonstrated to reside in the Fab part of the immunoglobulin. The S15 myeloma protein in 0.05 M Tris buffer at pH 7.4 precipitated dextran sulfate, heparin, chondroitin sulfate A, B and C, hyaluronic acid, H. influenzae type b polysaccharide, calf thymus DNA, Klebsiella polysaccharide K63 and poly-L glutamic acid. Of these antigens only dextran sulfate was precipitated in 0.01 M phosphate buffered saline (0.15M), pH 7.4. The pepsin S15 Fab fragment did not precipitate with any of these antigens. The intrinsic tryptophanyl fluorescence of S15 was changed maximally by the addition of heparin, and the binding affinity of the immunoglobulin for this antigen was high (greater than 10(6) L/M). S15 may resemble antibody molecules that react with antigens under non-physiological conditions or in pathological conditions or in the external environment as in the lumen of the gut. All the above interactions of S15 with antigens persisted in 0.05 M Tris buffer made physiologically isotonic by the addition of sucrose, and S15 could thus be used to identify these antigens on cell surfaces.

Membrane-bound glycoprotein in the alveolar cells of the caprine lung

An ultramicroscopic analysis of caprine lung glycoproteins, designed to detect plasmalemma-associated sulfoglycoprotein of alveolar type I and alveolar type II cells, was performed. High-iron diamine staining demonstrated a layer containing sulfated glycoproteins at the atypical plasmamembrane of alveolar type I cells and microvilli of alveolar type II cells. The cytoplasmic vesicles of the alveolar type I cell contained the reaction product on the inner leaflet of the vesicular unit membrane. The vesicles showed a variety of interactions with the apical plasma membrane. High-iron diamine staining also demonstrated sulfoglycoproteins in the cytoplasmic granules of the mast cells in the alveolar septum. The present study gives evidence that plasmalemma of the alveolar cells of the goat lung possesses exposed hyaluronic acid groups.

Cell surface proteoglycans as a negative modulator in concanavalin A-mediated agglutination of hepatoma cells

Proteoglycan (heparan sulfate-protein conjugate) was solubilized with 8 M urea from rat liver plasma membranes after enzymic (RNAase, neuraminidase) treatments and extensively purified by chromatography and gel filtration. The final products gave an average ratio of hexuronate to protein (weight) of approx. 1.5, contained hexosamine equimolar to hexuronate and were sensitive to beta-elimination (the molecular weight being reduced from 20 . 10(4) to 3 . 10(4) (gel filtration)). The proteoglycan fraction, when added to trypsinized and untrypsinized ascites hepatoma (AH-130F(N)) cells, inhibited the concanavalin A-mediated agglutination of the cells. However, the alkali-treated proteoglycan (beta-elimination) or acid mucopolysaccharide fraction prepared from liver plasma membranes by papain digestion were less effective, and a reference preparation of heparan sulfate was almost ineffective. It was confirmed that significant amounts of proteoglycan labelled with 35SO4(2-) were firmly bound to or taken up by the trypsinized ascites hepatoma cells. These results together with the sensitization of lectin-mediated agglutination by mild protease treatment of cells suggest that cell surface proteoglycans may act as a negative modulator in the lectin-mediated agglutination of cells.

Glycosaminoglycans: structure and interaction

In the last few years, there has been considerable progress in the studies on glycosaminoglycans, a group of acidic polysaccharides present in the intercellular matrix of connective tissue. X-ray diffraction studies have indicated that these polymers can exist in the condensed phase in some helical form. Chiroptical and hydrodynamic measurements have provided significant information regarding the molecular conformation in solution and other physicochemical properties of the polymers. Studies related to the interaction properties of glycosaminoglycans with polypeptides, metal ions, and other molecules are numerous. This review covers mainly the results and their interpretations of both published and as yet unpublished material of the 1970s, but certain previous data are also included. A present-day concept regarding the structure and interaction properties of these molecules on the basis of various physicochemical measurements is presented. The biosynthesis and metabolism of glycosaminoglycans, and the structure of proteoglycans and glycoproteins, are not discussed.

Interactions between chondroitin sulfate and concanavalin A

Chondroitin sulfate, the major extracellular matrix glycosaminoglycan, formed an insoluble complex with concanavalin A at pH 5.4 or below. Concanavalin A (500 microgram/ml) reacted only within a relatively narrow concentration range of chondroitin sulfate (optimally between 5 and 50 microgram/ml) at pH 5.4 in 0.05 M buffer. Similar precipitin-like interactions were seen between concanavalin A and hyaluronic acid or heparin. No precipitating complexes formed between concanavalin A and the glycosaminoglycans at these concentrations in physiological salt solutions (approx. 0.15 M) unless the pH was below 4.5. Precipitating self-aggregates of concanavalin A appeared to be promoted by chondroitin sulfate at pH 7.3, but no significant precipitation occurred between the reactants at this pH even at very high concentrations, nor did soluble complexes form as determined by affinity chromatography on Sephadex G-200 or fractionation on Bio-Gel P-200. Thus, binding between the lectin and glycosaminoglycans appeared to depend upon reversible non-specific electrostatic interactions observed only at low Ph and low ionic strength. Stable interactions were not seen in experiments using physiologically balanced salts at near neutral pH.