Purification of Plasma-Derived Coagulation Factor VIII by Immobilized-Zn2+ and -Co2+ Affinity Chromatography

Abstract

Coagulation factor VIII (FVIII) is a glycoprotein that plays a crucial role in the clotting cascade. Replacement therapies with recombinant and plasma-derived concentrates of FVIII are used for treatment of hemophilia A. We have previously purified the human plasma FVIII by immobilized metal affinity chromatography (IMAC) using Cu2+ as the metal ligand. In this work we report the purification of FVIII using Zn2+ and Co2+, two metal ions that bind proteins more weakly. Human plasma was directly applied to the anion-exchange ANX Sepharose FF column and the eluate was used as starting material for the studies in IMAC columns. Using imidazole as desorbing agent, FVIII was recovered with 65% activity in the IMAC-Zn2+ column and with 74% activity in the IMAC-Co2+ column. Purification factors were 4 and 9, respectively. Using a pH gradient, FVIII was eluted at pH 5.0 with 17% activity in the IMAC-Zn2+ and 77% activity in the IMAC-Co2+. Vitamin K-dependent proteins, a family of proteins that includes Prothrombin and coagulation factor IX, coeluted with FVIII in the ANX Sepharose FF column and were recovered with the unbound proteins on both IMAC columns. Therefore, Co2+ and Zn2+ columns were as effective as the Cu2+ column in separating FVIII from vitamin K-dependent proteins. Finally, we have shown that FVIII remained complexed with the von Willebrand factor.