Alterations of the glycan moiety of human alpha 1-acid glycoprotein in late-term pregnancy.

ABSTRACT

The carbohydrate moiety of purified alpha 1-acid glycoprotein (AGP) from healthy male adults (AGPn) and late-term pregnant women (AGPp) was analysed. Polyacrylamide gel electrophoresis with sodium dodecyl sulfate before and after N-glycanase treatment showed that AGPp had a slightly higher molecular mass due to an enriched carbohydrate moiety. BIO-GEL P-4 and Concanavalin A (Con A)-Sepharose chromatography of the oligosaccharides released by hydrazinolysis and fractionated by high-voltage electrophoresis indicated a progression towards Con A-unbound oligosaccharides and towards larger glycans in pregnancy. Carbohydrate analysis of purified AGPp and AGPn and of the most increased oligosaccharide fraction (F4A) evidenced a decrease in the fucosyl molar ratio and a slight increase in the galactosyl, N-acetyl-glucosaminyl and N-acetyl neuraminyl ratios. These results suggest that AGP contains more highly branched oligosaccharides and/or additional N-acetyllactosamine-type oligosaccharides in pregnancy.