Purification of α1 proteinase inhibitor from human plasma fraction IV-1 by ion exchange chromatography

Background and Objectives: alpha-proteinase inhibitor (PI) protects the lungs from proteolytic damage caused by elastase and can be used to treat congenital emphysema. We describe an improved method of purification of alpha(1) PI from redissolved fraction IV-1 paste. Materials and Methods: The process used dimethylaminoethyl anion exchange chromatography, sulfopropyl cation exchange chromatography, virus inactivation by dry heat, and tri-n-butyl-phosphate/cholate treatment, followed by a second strong cation exchange chromatography. Optimizations of loading conditions for ion exchange chromatography at small scale (20-60 ml of suspension) are described. Virus inactivation was adjusted to provide the best yield of alpha(1) PI consistent with effective inactivation. The process has been effectively scaled up. Results: The final product was approximately 90% pure by SDS-PAGE, with a 60-70% yield from starting fraction IV-1 paste. The process has been characterized by methods including nonreduced SDS-PAGE, alpha(1) PI inhibition assay, and biuret protein assay. Conclusion: The method described is an effective way of preparing large quantities of alpha(1) PI from fractionated plasma.