Polyanionic glycosaminoglycans

U. Lindahl Glycosaminoglycans polyanions with built-in messages J. H. Shaper Glycosyltransferases transscriptional regulation... 

The property of polyanions to give metachromatic reactions with basic dyes80 (see Section XI) has been widely exploited for the titration of glycosaminoglycans. Because of its high charge-density, heparin displays large shifts in the visible spectrum of the dye upon complex-formation, and can conveniently be titrated (most commonly, with Methylene Blue or Azure A), even in the presence of minor proportions of other glycosaminoglycans. It should be realized that quantitative responses with metachromatic dyes are different for different pure heparin... 

Heparin in mixtures of glycosaminoglycans can also be titrated to a turbidimetric end-point with such quaternary ammonium salts as CPC, at a sufficiently high concentration of salt to prevent complex-formation by less-charged polyanions.38... 

Based on our knowledge of the facts that (a) lipoproteins are carriers of cholesterol in the blood stream, (b) they are involved in atherogenesis,(c) pectin when supplemented in diet causes lowering of serum and/or liver cholesterol in man as well as a number of laboratory animals and (d) polyanionic glycosaminoglycans interact with lipoproteins, it was of interest to us to investigate the interaction of polyanionic pectin with lipoproteins in order to explain the biochemical basis by which pectin may cause lowering of serum/liver cholesterol levels. 

Our preliminary experiments suggest that, like the interaction between glycosaminoglycans and lipoproteins, the interaction between pectin and lipoprotein is also caused by the electrostatic attraction between polyanionic pectin and cationic lipoprotein. To elucidate this hypothesis, the charge profile of lipoproteins will be altered chemically and the influence of these alterations on the interaction with pectic polysaccharides at optimum experimental conditions will be determined. 

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