| Early photolysis intermediates of gecko and bovine artificial visual pigments. | |
|---|---|
| Lewis JW; Liang J; Ebrey TG; Sheves M; Livnah N; Kuwata O; Jager S; Kliger DS | |
| Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA. | |
| Biochemistry 1997 Nov 25;36(47):14593-600 | |
| 98062927 | |
| ABSTRACT: | Nanosecond laser photolysis measurements were conducted on digitonin extracts of artificial pigments prepared from the cone-type visual pigment, P521, of the Tokay gecko (Gekko gekko) retina. Artificial pigments were prepared by regeneration of bleached gecko photoreceptor membranes with 9-cis-retinal, 9-cis-14-methylretinal, or 9-cis-alpha-retinal. Absorbance difference spectra were recorded at a sequence of time delays from 30 ns to 60 microseconds following excitation with a pulse of 477-nm actinic light. Global analysis showed the kinetic data for all three artificial gecko pigments to be best fit by two-exponential processes. These two-exponential decays correspond to similar decays observed after photolysis of P521 itself, with the first process being the decay of the equilibrated P521 Batho<-->P521 BSI mixture to P521 Lumi and the second process being the decay of P521 Lumi to P521 Meta I. In spite of its large blue shift relative to P521, iso-P521 displays a normal chloride depletion induced blue shift. Iso-P521's early intermediates up to Lumi were also blue-shifted, with the P521 Batho<-->P521 BSI equilibrated mixture being 15 nm blue-shifted and P521 Lumi being 8 nm blue-shifted relative to the intermediates formed after P521 photolysis. The blue shift associated with the iso-pigment is reduced or disappears entirely by P521 Meta I. Similar blue shifts were observed for the early intermediates observed after photolysis of bovine isorhodopsin, with the Lumi intermediate blue-shifted 5 nm compared to the Lumi intermediate formed after photolysis of bovine rhodopsin. These shifts indicate that a difference exists between the binding sites of 9- and 11-cis pigments which persists for microseconds at 20 degrees C. |
| MAIN MESH SUBJECTS: | Cones (Retina)/*PHYSIOLOGY/RADIATION
EFFECTS
Retinaldehyde/*ANALOGS & DERIVATIVES/CHEMISTRY/*METABOLISM/ RADIATION EFFECTS Rhodopsin/*ANALOGS & DERIVATIVES/CHEMISTRY/*METABOLISM/RADIATION EFFECTS |
| ADDITIONAL MESH SUBJECTS: | Animal
Cattle Cell Membrane/PHYSIOLOGY Kinetics Lizards Photolysis Species Specificity Spectrophotometry Support, U.S. Gov't, P.H.S. |
| PUBLICATION TYPES: | JOURNAL ARTICLE |
| LANGUAGE: | Eng |
| REGISTRY NUMBERS: | 116-31-4 (Retinaldehyde)
9009-81-8 (Rhodopsin) |
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