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1	Author	W. Häberle, H. G. Ruler, Ph Dutkowski, D. Müller-Enoch	Requires cookie*
	Title	Light-Induced Activation and Synchronization of the Cytochrome P-450 Dependent Monooxygenase System
	Abstract	The light-induced enhancement o f the 7-ethoxycoumarin-O-deethylase activity was m eas ured in a reconstituted system, consisting o f the enzyme P-450pb_b and the N A D P H -cyto-chrome P-450 reductase. The relative increase o f the activity was about 15%. It is shown that the product release process is accelerated by light. The phases o f the catalytic cycle o f 2 x 1012 protein complexes were locked by periodic application o f light pulses (0.1 s duration, 1.32 s repetition time, and 3 9 0 -4 7 0 nm, 0.27 joule/nm ol P-450). More than 80% o f the active recon stituted enzyme com plexes (= "molecular machines") worked in phase after a few light pulses. The phase relation continued even after switching o ff the light pulses. The catalytic cycle time was 1.54 s, giving a turnover number o f 39 min-1. The turnover number, as determined from the enzyme activity under optimum conditions, was 39 m in-1. Due to the dissociation constant o f the P-450pb_b:N A D P H -P -450 reductase complexes [3] only 24% o f the proteins were in the active (= working) state under the conditions used. The lifetime o f this complexes is larger than 6 s since more than 4 cycles o f the free running enzyme can be observed. This is the first report, that all catalytic active complexes in the test tube can be synchronized by an external light source, if the right repetition time o f the pulses is chosen, so that all these "molecular machines" work in phase.
	Reference	Z. Naturforsch. 45c, 273 (1990); received September 14/November 28 1989
	Published	1990
	Keywords	Cytochrome P-450, Light-Induced Activation and Synchronization, Catalytic Cycle Time
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	TEI-XML for	default:Reihe_C/45/ZNC-1990-45c-0273.pdf
	Identifier	ZNC-1990-45c-0273
	Volume	45