Carbohydrate composition of serum transferrin isoforms from patients with high alcohol consumption.

Normal human serum transferrin is present in several isoforms, due to differences in glycosylation. Transferrin has two potential glycosylation sites, both normally occupied by oligosaccharide chains. Two of the transferrin isoforms, called carbohydrate deficient transferrin, are specifically increased in patients with high alcohol consumption. In this study, five isoforms of transferrin were isolated from patients with high alcohol consumption. N-linked glycans were released by N-glycosidase digestion and were radioactively labeled by NaB3H4 reduction. The purified oligosaccharides were analyzed by high-pH anion-exchange chromatography, and the carbohydrate composition of each individual transferrin isoform was determined. The carbohydrate deficient transferrin isoforms were found to lack one or both of their entire carbohydrate chains.