The structures of xylosylserine and galactosylxylosylserine from heparin

Two carbohydrate-serine compounds from heparin have been further characterized. The structures of these substances, O-β-d-xylopyranosyl-l-serine and 4-O-β-d-galactopyranosyl-O-β-d-xylopyranosyl-l-serine, respectively, were found to be identical with those of xylosylserine and galactosylxylosylserine from chondroitin 4-sulfate. These findings conclusively establish that the heparin-protein linkage is a xylosidic bond involving the hydroxyl group of serine.