title: Slaving the cytochrome P-450 dependent monooxygenase system by periodically applied light pulses.
abstract: 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.
authors.affiliation: Institut für Biophysik, Universität Ulm, Federal Republic of Germany.
authors.forename: H
authors.initials: H
authors.lastname: Gruler
authors.forename: D
authors.initials: D
authors.lastname: Müller-Enoch
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase / Q000378:metabolism; D000818:Animals; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004789:Enzyme Activation; D008027:Light; D008099:Liver / Q000201:enzymology; D046911:Macromolecular Substances; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism*; D010507:Periodicity; D051381:Rats; D013050:Spectrometry, Fluorescence; D013252:Steroid 11-beta-Hydroxylase / Q000378:metabolism
chemical_list: D046911:Macromolecular Substances; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D013252:Steroid 11-beta-Hydroxylase; D009251:NADPH-Ferrihemoprotein Reductase