Dark Isomerization of Retinals in the Presence of Phosphatidylethanolamine
- 1 May 1980
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 106 (1), 119-128
- https://doi.org/10.1111/j.1432-1033.1980.tb06002.x
Abstract
Dark incubation of retinoids (retinyl ester, retinol, retinal and retinaloxime) in suspensions of rod outer segment membranes leads to substantial isomerization (and partial degradation) only in retinals. All-trans, 13-cis and 9-cis-retinal all isomerize at the .DELTA.13 double blood leading to an equilibrium with .apprx. 75% trans and 25% cis isomer at this bond (all-trans .dblarw. 13-cis and 9-cis .dblarw. 9,13-dicis). 11-cis-Retinal isomerizes irreversibly to a mixture of all-trans and 13-cis-retinal. The active compound in the membrane is apparently phosphatidylethanolamine. The amino group, phosphate and the hydrophobic part of the phospholipid are essential. At least 3 factors are important for the phosphatidylethanolamine-catalyzed isomerization: the concentration of phosphatidylethanolamine, the concentration of Schiff base between retinal and phosphatidylethanolamine and the presence of lipid aggregates. A mechanism is proposed which satisfactorily explains the specificity of the isomerization pattern. Reisomerization of all-trans to 11-cis retinal in vivo apparently takes place by fixation of all-trans retinal on an adequate surface (e.g., opsin) and a localized nucleophilic attack on the C-11 atom, followed by trapping of the isomerized chromophore by opsin. Retinal apparently does not occur in vivo as a free intermediate. Direct transfer from 1 protein to another (opsin, retinol dehydrogenase and retinal binding proteins) seems to take place.This publication has 35 references indexed in Scilit:
- Photochemistry and dark equilibrium of retinal isomers and bacteriorhodopsin isomersEuropean Biophysics Journal, 1977
- The structure of visual pigments. I. Carbon-13 nuclear magnetic resonance spectroscopy of N-all-trans-retinylidenepropylimine and its protonated speciesJournal of the American Chemical Society, 1976
- The stability of 11-cis-retinal and reactivity toward nucleophilesBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1974
- On the rhodopsin cycleExperimental Eye Research, 1974
- Recent studies on a possible mechanism for visual pigment regenerationExperimental Eye Research, 1974
- Biochemical aspects of the visual process. XIX. Formation of isorhodopsin from photolyzed rhodopsin by bacterial actionBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1972
- Enzymes in the regeneration of rhodopsinBiochemical and Biophysical Research Communications, 1972
- Crystal Structure of the Visual Chromophores, 11-cis and all-trans RetinalNature, 1971
- The Condensation of Long-Chain Aldehydes to 2,3-Dialkylacroleins in the Presence of Ethanolamine PhosphatidesHoppe-Seyler´s Zeitschrift Für Physiologische Chemie, 1968
- Geometrical Isomerization of Vitamin A, Retinene and Retinene OximeJournal of the American Chemical Society, 1956