LARGE-SCALE PREPARATION AND BIOCHEMICAL-CHARACTERIZATION OF A NEW HIGH-PURITY FACTOR-IX CONCENTRATE PREPARED BY METAL CHELATE AFFINITY-CHROMATOGRAPHY

Metal chelate affinity chromatography on copper-charged Chelating Sepharose has been used to purify a factor IX concentrate from 4 000- to 5 000-kg pools of human plasma, with an overall yield of 194 IU/kg. Unwanted proteins and solvent-detergent reagents added to inactivate lipid-enveloped viruses were removed during the chromatographic step. The freeze-dried product was > 80% pure factor IX with a mean specific activity of > 160 IU/mg protein. The concentrate showed no evidence of clotting factor activation by in vitro tests for potential thrombogenicity or by direct assay for activated factor IX. The concentrate did not exhibit proteolytic activity against a range of synthetic peptide chromogenic substrates. Full functional factor IX activity was retained and there was no evidence of protein degradation. Metal chelate affinity chromatography therefore appears to present less physicochemical challenge to the protein than other factor IX purification methods, while allowing the preparation of a clinical factor IX concentrate at a large scale.