Electrophoretic properties and biochemical characterization of recombinant antithrombin glycoforms. (A) Antithrombin glycoforms expressed in HEK-EBNA when transfected with pCEP4/AT-S137A (left) or with pCEP4/AT WT (right) plasmid. The medium containing the secreted recombinant protein was run under reduced SDS conditions and detected by Western blot. (B) SDS-PAGE and silver staining of recombinant glycoforms of WT, R47C, and P41L antithrombin purified by heparin affinity chromatography and anion exchange chromatography. (C) Crossed immunoelectrophoresis in the presence of unfractionated heparin of purified recombinant α- and β-P41L glycoforms. The antithrombin forms of high and low heparin affinity are indicated.