Uniformity of Glycans within Molecular Variants of αl‐Protease Inhibitor with Distinct Affinity for Concanavalin A

Abstract

Human .alpha.1-protease inhibitor contains 4 asparagine-linked carbohydrate chains/molecule. Three types of carbohydrate chains were released from the polypeptide backbone by hydrazinolysis: (a) biantennary (80%), (b) biantennary with an intercalated N-acetylglucosamine residue (14%), and (c) triantennary (6%). Using concanavalin-A-affinity chromatography, native and S-carboxymethylated .alpha.1-protease inhibitor were fractionated into 3 distinct molecular variants which were shown to contain only one type (a, b or c, respectively), of glycan/molecule. This and previous observations on other serum glycoproteins support the proposal of uniformity of glycan type within individual molecular variants of glycoproteins.