Glycoproteins of the opium poppy

Two carbohydrate-protein fractions were isolated from the water-soluble biopolymer from opium poppy capsules by chromatography on SP-Sephadex. The carbohydrate chains are composed of arabinose, rhamnose, xylose, mannose, glucose, galactose, galacturonic acid, glucuronic acid and 4-O-methyl glucuronic acid. Methylation analysis indicated a high degree of branching suggesting a very complex structure. Treatment of the glycoprotein with NaOH in the presence of NaBH₄ resulted in a significant decrease in the serine and threonine content. The carbohydrate side chains released contained the sugar alcohol, galactitol. These results indicate that polysaccharide chains are linked to protein via serine-O-galactoside linkages.