Biochemistry 1994,33, 13741- 13750
13741
Rod Outer Segment Retinol Dehydrogenase: Substrate Specificity and Role in Phototransduction? Krzysztof Palczewski,e,@Stefan Jager,l Janina Buczy€ko,$ Rosalie K. Crouch,*JID. Lucille Bredberg,$ Klaus Peter Hofmann,l Mary Ann Asson-Batres,$ and John C. Saari*,v Departments of Ophthalmology, Pharmacology, and Biochemistry, University of Washington, Seattle, Washington, Institut f i r Biophysik and Strahlenbiologie, Universitat Freiburg, 79104 Freiburg, Federal Republic of Germany, and Departments of Biochemistry and Ophthalmology, Medical University of South Carolina, Charleston, South Carolina 29425-2501 Received June 10, 1994; Revised Manuscript Received September 7, 1994@
ABSTRACT: The reaction catalyzed by all-trans-retinol dehydrogenase of rod outer segments completes
the quenching of photoactivated rhodopsin and initiates the cycle of reactions leading to regeneration of visual pigment. The goal of this study was to determine the kinetic parameters of the dehydrogenase at physiological levels of bleaching, to investigate its specificity, and to determine its possible role in modulating phototransduction. Reduction of all-trans-retinal could be measured after bleaching
