The glycosaminoglycan synthesis in Furth solid mastocytoma tissue has been studied. Approx. 10% of the polysaccharide isolated after incubation in vitro with [14C]-glucosamine was digestible with chondroitinase ABC and the product of digestion was identified as 2-acetamido-2-deoxy-3-O-(β-d-gluco-4-enepyranosyluronic acid)-4-O-sulpho-d-galactose. Similarly, labelling of polysaccharide in vivo with 35SO42− followed by isolation of mast-cell fractions by density-gradient centrifugation on colloidal silica revealed the presence of a polysaccharide which migrated as did chondroitin sulphate on electrophoresis in barium acetate. Chondroitinase ABC produced the same digestion product as before. Finally, the presence of the UDP-N-acetylgalactosamine–chondroitin 6-sulphate hexasaccharide N-acetylgalactosaminyltransferase previously implicated in chondroitin sulphate biosynthesis was demonstrated in microsomal particles from fractions of purified mast cells.
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