SCALED-UP PRODUCTION OF RECOMBINANT HUMAN RENIN IN CHO CELLS FOR ENZYMATIC AND X-RAY STRUCTURE-ANALYSIS

A process was developed to produce recombinant human renin for X-ray a nalysis and enzyme inhibition studies. An expression vector containing a human prorenin cDNA and expressing a mouse dihydrofolate reductase selection marker was transfected into dhfr-minus Chinese hamster ovary cells. After selection of cell strains with an increased gene copy nu mber with methotrexate, cultures of the recombinant cells were scaled- up in serum-free media. Major improvements in cellular productivity we re achieved by using continuous suspension cultures with cell recyclin g instead of an adherent culture system or batch-mode suspension cultu res. The recombinant zymogen prorenin was purified and preparatively a ctivated with trypsin. Enzymatic properties of the recombinant active renin are described.