Artificial Flavin/Membrane Systems; a Possible Model for Physiological Blue Light Action
The blue light photoreceptor responsible for a great variety of physiological responses is most likely a flavin, bound in a highly dichroic manner to a membrane moiety [10, 11, 28]. The mechanism termed sensory transduction, by which the impinging blue light is transformed into a biochemical equivalent, appears to be a flavin-mediated photo-redox reaction. This is suggested by several observations. (1) Molecular oxygen is a necessary prerequisite for the primary blue light action [9, 21, 27]. (2) Oxidizing agents are capable of simulating physiological blue light action  and consequently reducing agents are capable of suppressing it [1, 26]. (3) The primary step of blue light action is temperature-independent [6, 7, 16, 20, 21]. (4) Photodynamically active dyes act as (artificial) photoreceptors, photodynamically inactive dyes do not [3, 13]. (5) Inhibitors of light-driven, flavin-mediated electron flow inhibit physiological blue light responses specifically [18, 23]. (6) The blue light-induced, dark-reversible photoreduction of a b-type cytochrome, as observed in several blue light-sensitive organisms, appears to be correlated to physiological primary reaction of blue light . Redox reactions of caro-tenoids appear to be physiologically irrelevant.
KeywordsFluorescence Polarization Polar Head Group Membrane Phase Rotational Relaxation Liquid Crystalline State
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