Chromatographic purification of human α1 proteinase inhibitor from dissolved Cohn fraction IV-1 paste

A novel chromatographic process for purification of α₁ proteinase inhibitor (α₁-PI) from Cohn fraction IV-1 paste is described. This process has been successfully scaled up to 50-l columns. It involves DEAE chromatography, sulfopropyl (S) cation chromatography, tri-n-butyl phosphate (TNBP)–cholate treatment, a second S cation chromatography, freeze–drying and dry-heat. The process has been optimized for purity, yield, lipid removal, chemical usage and water consumption. Filtration after TNBP–cholate treatment plays a key role in ensuring a low lipid content in the final product. Pre-equilibration with high salt buffer is necessary to reduce the water consumption significantly during the ion-exchange chromatography equilibration step. The final product is approximately 95% pure by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, with a 64% to 70% yield from IV-1 paste.