Characterization of a Glucose Polymer from PC12 Cells and Neuronal Cells of Rat Embryo

Abstract

A large-sized glucose polymer was isolated by pronase digestion from line PC12 pheo-chromocytoma cells metabolically labeled with [1-³H] galactose. The polymerwas included on a column of concanavalin A-Sepharose and could be eluted with 10mM methyl-α-mannoside. Its slight retention in a column of Bio-Gel A-5m suggested that its molecular weight was in the several millions. Glucose was the component monosaccharide and there were two minor lipophilic components present. The polymer was digested with α-amylase into a series of oligosaccharides and was cleaved by glucoamylase into glucose residues. The disaccharide obtained by digestion with α-amylase was identified as maltose in several HPLC systems and by NMR spectroscopy. NMR measurement revealed the trisaccharide to be maltotriose. Susceptibility of the polymer molecule to α-amylase, and the digestion products obtained, indicated a resemblance to glycogen. An analysis for saccharide compositions before and after reduction of the polymer suggested the presence of an aglycon part.Contrary to expectations based on the presence of this moiety, the polymer displayed good solubility in neutral organic solvents. Two-thirds of the glucose polymer was also soluble in 10% TCA. A similar glucose polymer was isolated from neuronal cells of rat embryos metabolically labeled with [1-³H] galactose. Mouse neuroblastoma cells did not synthesize the polymer.