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 analysis 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 number with methotrexate, cultures of the recombinant cells were scaled-up in serum-free media. Major improvements in cellular productivity were achieved by using continuous suspension cultures with cell recycling instead of an adherent culture system or batch-mode suspension cultures. The recombinant zymogen prorenin was purified and preparatively activated with trypsin. Enzymatic properties of the recombinant active renin are described.