COEXPRESSION OF A HUMAN P450 (CYP3A4) AND P450 REDUCTASE GENERATES A HIGHLY FUNCTIONAL MONOOXYGENASE SYSTEM IN ESCHERICHIA-COLI

The catalytic activities of recombinant cytochrome P450s expressed in E. coli have been impeded by the absence of endogenous p450 reductase, To solve this problem, we coexpressed p450 reductase with CYP3A4. Mem branes from this strain contained 215 pmol P450/mg protein and a reduc tase activity of 1315 nmol cytochrome c reduced/min per mg, We detecte d 6 beta-hydroxylation of testosterone and oxidation of nifedipine in vivo with turnover numbers of 15.2 and 17.3 min(-1), respectively. The se values compare favourably with those obtained using an optimally re constituted system, Our data demonstrate that a catalytically efficien t human P450 system can be generated in E. coli.