Slaving the cytochrome P-450 dependent monooxygenase system by periodically applied light pulses

The light-induced enhancement of 7-ethoxycoumarin-O-deethylase activity was measured in a reconstituted system consisting of the enzyme P-450 II B1 (P-450PB-B) and the NADPH-cytochrome P-450 reductase. The phases of the catalytic cycle of 2 x 10(12) protein complexes were locked by periodic application of light pulses (0.1 s duration, 1.2-2.5 s repetition time, and 390-470 nm 0.27 Joule/nmol P-450). More than 80% of the active reconstituted enzyme complexes worked in phase if the repetition time (1.32 s) was slightly smaller than the catalytic cycle time of the free running enzyme (1.54 s). The percentage of synchronized enzyme complexes as a function of the repetition time is shown. It is shown that the lifetime of the product-enzyme complex is shortened by the light.