Determination of the structure of the carbohydrate chains of prostaglandin endoperoxide synthase from sheep

Abstract

Prostaglandin endoperoxide synthase was isolated from sheep seminal vesicles. Sugar analysis of the glycoprotein revealed the presence of mannose and N-acetylglucosamine only. The carbohydrate moiety was released from the polypeptide backbone by hydrazinolysis. After re-N-acetylation and reduction, the resulting mixture of oligosaccharide-alditols was fractionated on Bio-Gel P-4 and their structures were investigated by 500-MHz ¹H-NMR spectroscopy. The carbohydrate chains turned out to be of the oligomannoside type containing six to nine mannose residues. The largest and most abundant compound was established to be: For the smaller structures heterogeneity occurs with respect to the outer α(1 → 2)-linked mannose residues. Furthermore, a small amount of Man₆GlcNAc-ol (artefact of the hydrazinolysis procedure) was detected by ¹H-NMR spectroscopy and fast atom bombardment mass spectrometry.