CHANGE IN GLYCOSYLATION OF CHICKEN TRANSFERRIN GLYCANS BIOSYNTHESIZEDDURING EMBRYOGENESIS AND PRIMARY CULTURE OF EMBRYO HEPATOCYTES

Transferrins were isolated by immunoaffinity chromatography from chick en serum, chicken embryo serum and from the culture medium of chicken embryo hepatocytes in primary culture. The glycovariants of these thre e transferrins were separated by ion-exchange chromatography using a f ast protein liquid chromatography (FPLC) system. The structures of the oligosaccharide-alditols released by hydrazinolysis from the glycovar iants were compared after analysis by a combination of methanolysis, m ethylation analysis and H-1-NMR spectroscopy. In the three transferrin s analysed, the oligosaccharides were of the biantennary N-acetyllacto saminic type, having several prominent features. In particular, the em bryo serum transferrin glycan differed from that of chicken serum tran sferrin by the presence of a bisecting N-acetylglucosamine, suggesting a developmental change in glycosylation. The glycan structure of the transferrin secreted by the embryo hepatocytes in primary culture was marked by the presence of fucose (alpha 1-6) linked to the core N-acet ylglucosamine, suggesting that expression of the fucosyltransferase ac tivity is dependent on cell culture conditions. Moreover, comparative analysis of chicken serum transferrin and ovotransferrin glycans reinf orces the idea that the glycosylation of two identical polypeptide cha ins is organ specific.