PURIFICATION OF ISOTRANSFERRINS BY CONCANAVALIN-A SEPHAROSE CHROMATOGRAPHY AND PREPARATIVE ISOELECTRIC-FOCUSING

1. From pooled serum containing genetically homogeneous transferrin C- 1, transferrin was purified and separated in three fractions (tri-tri- , bi-tri- and bi-bi-antennary transferrin C-1), using Concanavalin A-S epharose. 2. Each of these fractions was separated into its sialic aci d-dependent subfractions by preparative isoelectric focusing. Sixteen iso-transferrin C-1 fractions were obtained, which differed in their d egree of glycan branching and/or their sialic acid content. 3. Prelimi nary carbohydrate analyses suggest that in some iso-transferrins the N -acetylglucosamine and the galactose content is lower than expected.