Effect of harvest medium composition on yield and chain nature of recombinant tissue-type plasminogen activator...

The effect of harvest medium composition on yield and quality of two recombinant tissue type plasminogen activators (t-PA) has been examined. Protein hydrolysates increased the yield of native t-PA up to 3-fold compared to control cultures. In marked contrast, the yield of a growth-factor deleted t-PA mutant was adversely affected by the use of these additives. Partially purified t-PA that had been harvested in the presence of protein hydrolysates had higher fibrin plate activity: amidolytic activity ratios. In addition Western blotting showed these preparations contained less degraded material. These observations suggest that protein hydrolysates have opposite effects on two closely related recombinant cell lines and that they can affect quality as well as yield of secreted proteins.