INVESTIGATION OF RECOMBINANT ANTITHROMBIN III PRODUCED BY BHK CELLS DURING FERMENTATION PROCESSES

Abstract

Efficient recombinant protein production processes should optimize both productivity and yield. The fermentation process should also preserve the integrity and quality of the desired protein product. AT III (antithrombin III) is one of the most important serine protease inhibitors in plasma. It is an @,-glycoprotein of M, 60,000 to 64,000 containing three or four polysaccharide chains attached by N-glycosidic linkage to asparagine residues. The biological activity of AT III can be enhanced 2-3 orders of magnitude by binding with the cofactor heparin (1). Affinity chromatography of plasma-derived AT III on immobilized heparin resulted in two fractions of AT II which differ from each other in their affinity to heparin; their difference in affinity to heparin is due to different degrees of glycosylation (2). Concerns have been raised that if BHK-derived AT III exhibit the same behavior on purification as its plasma-derived counterpart. In the fermentation of AT III producing BHK (baby hamster kidney) cells, productivity was monitored and the possible influence of serum-free cultivation conditions on protein quality in termsof both integrity (against proteolytic activity) and affinity to heparin was investigated.