Patent ID: 8921530

Claim:
A method for purification of a gamma-carboxy-glutamic (GLA)-residue containing serine protease in solution, wherein the GLA-residue containing serine protease is a recombinant Factor IX polypeptide, the method comprising: subjecting the solution to one or more purification steps selected from the group consisting of anion exchange chromatography, hydrophobic interaction chromatography, immunoaffinity purification, size exclusion chromatography, diafiltration, and ultrafiltration, adjusting calcium in the solution to obtain a molar ratio of free calcium ions and Factor IX polypeptide (Ca2+:FIX polypeptide) lower than 0.5; and adjusting the pH of the solution to a value between 4.5 and 6.9 or to a value between 8.6 and 10.