The purification of human serum 1 -antitrypsin by affinity chromatography on concanavalin A

α₁-Antitrypsin (α₁-AT) has been isolated from human serum by a two-step procedure which involves chromatography on DEAE-Sephadex followed by affinity chromatography on insolubilized concanavalin A. This protein appeared to be homogeneous when examined by electrophoresis on cellulose acetate and double immunodiffusion; minor contaminants, however, were detected by gel electrophoresis and immunoelectrophoresis. This procedure is readily adaptable to the large-scale purification of α₁-AT and should facilitate further studies on the physicochemical and biological properties of α₁-AT and its genetic variants.