O-Acetylated Oligosaccharides from Pectins of Potato Tuber Cell Walls

Acetylated trigalacturonides and rhamnogalacturonan I (RG-I)-derived oligosaccharides were isolated from a Driselase digest of potato tuber cell walls by ion-exchange and size-exclusion chromatography. The oligosaccharides were structurally characterized by fast atom bombardment-mass spectroscopy, nuclear magnetic resonance spectroscopy, and glycosyl-linkage composition analysis. One trigalacturonide contained a single acetyl group at O–3 of the reducing galacturonic acid residue. A second trigalacturonide contained two acetyl substituents, which were located on O–3 or O–4 of the nonreducing galacturonic acid residue and O–3 of the reducing galacturonic acid residue. RG-I backbone-derived oligomers had acetyl groups at O–2 of the galacturonic acid residues. Some of these galacturonic acid residues were O-acetylated at both O–2 and O–3 positions. Rhamnosyl residues of RG-I oligomers were not acetylated.