Inhibition of Bluelight-Induced, Flavin-Mediated Membraneous Redoxtransfer by Xenon

Privatdozent für Biophysik, Universität Konstanz, Fakultät für Biologie, Postfach 5560, D-7750 Konstanz 1 Z. Naturforsch. 40c, 451—453 (1985); received February 19, 1985/March 22, 1985 Cryptochrome, Xenon, Flavin Singlet/Flavin Triplet, Bluelight-Physiology, Membran-Redox Transport (LightInduced) Xenon as a potential triplet quencher is capable of in­ hibiting bluelight-induced, flavin-mediated transport of redox-equivalents across lipid membranes. The experiments described are based on a model system developed recently. Ferricytochrome c as a potential electron acceptor is trap­ ped in the lumen of unilamellar lipid vesicles, EDTA* as a potential electron donor added to the bulk volume and amphiphilic flavin as a mediator bound to the vesicle mem­ brane. However, Under isotropic aqueous conditions the bluelight-driven electron transport chain comprising EDTA, flavin and Cyt c is not significantly affected by xenon. These data call for the reinterpretation of results obtained with xenon as potential inhibitor of phototropic curvature of grass coleoptiles. which were taken to suggest the flavin singlet as active species.