with the vero vaccinia expression system described above was applied to the column with a speed of 1 ml min material not bound to the column is removed by washing with buffer a with the same flow speed then by mixing buffer a and buffer b the column was eluted in a 50 ml volume by means of a linear nacl gradient from 150 mm to 300 mm fractions of 2 ml were collected during the chromatography the protein absorption was followed in the customary manner at 280 nm the protein concentration was determined by means of the bradford method m bradford anal biochem 72 1976 248 254 and the activity of factor ix by means of a commercial coagulation test factor ix coagulation immuno ag the concentration of factor ix antigen was determined by means of elisa diagnostica stago fig1 shows the chromatography profile obtained according to example 1 thereby it was established that factor ix antigen was eluted from the column in two separate elution ranges fractions 22 to 28 and fractions 29 to 35 the examination by means of denaturing electrophoresis u k laemmli nature 227 1970 680 685 established that the factor ix antigen of fractions 22 to 28 has a higher molecular weight of about 2000 over the factor ix antigen of fractions 29 35 fig2 the examination of the clotting profile of the elution fractions established that physiologically active factor ix was only obtained in the fractions 29 to 35 table 1 table 1______________________________________separation of pro factor ix and factor ix by linear anion exchange chromatography volume f ix ag f ix c material ml u u f ix.