Abstract
A physical model that incorporates all the experimental information on the formation of the visual pigment rhodopsin is presented. The visual pigments consist of a chromophore bound to an appropriate protein. Thus rhodopsin (λm 505 mμ) is formed by a Schiff’s base linkage C19H27CH=NH+-opsin (λm 440 mμ) between 11-cis retinal (λm 380 mμ) and the protein opsin (λm 280 mμ). It is found that there exists a red shift in the spectrum of rhodopsin from the Schiff’s base. The model brings an explanation for this red shift. It is shown that such a shift may be due to a charge transfer process (R. S. Mulliken,J. Am. Chem. Soc.,74, 811–824, 1952) between an electron at the double bond of carbons C11−C12 and an atomic orbital of the sulphur present in cysteine. This provides an explanation of the presence of SH-groups in the protein after the absorption of light. A one-electron approximation is used and the dipole momentμ NV ; hence, the oscillator strengthf of the transitionNV is estimated and compared with the experimentally determined extinction coefficient ∈m by mixing 3.5×10−3 M of 11-cis retinal with 8.3×10−5 M of cysteine at pH ranges 6 through 8. Reasonable agreement is found. Solvent, concentration and temperature dependence are shown also.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Literature
Ball, S., F. D. Collins, P. D. Dalvi and R. A. Morton. 1949. “Studies in Vitamin A No. 11. Reactions of Retinine1 with Amino Compounds.”Biochem. J.,45, 304–307.
Bellin, J. J. 1965. “Properties of Pigments in the Bound State.”Photobiol. and Photochem.,4, 33–44.
Berthod, H. and A. Pullman. 1960. “Aspects de la structure electronique du retinene et de ses isomeres d’interet biologique.”Acad. Sci., Paris. Comptes Rendus 251, 808–810.
Brown, P. K. and G. Wald. 1958. “The Neo-b Isomer of Vitamin A and Retinene”J. Biol. Chem.,222, 865–877.
Cone, R. A. 1967. Early Receptor Potential: Photoreversible Charge Displacement in Rhodopsin.Science,155, 1128–1113.
Fernandez-Moran, H. 1954. “Submicroscopic Structure of Nerve Fibres.”Prog. Biophys.,4, 112–147.
Hubbard, R. and A. Kropf. 1958. “The Action of Light on Rhodopsin.”Proc. Nat. Acad. Sci., U.S.,44, 130–139.
——. 1959. “Molecular Aspects of Visual Excitation.”Ann. N.Y. Acad. Sci.,81, 388–398.
Ishigami, M., Y. Maeda and K. Mishima. 1966. “A Retinene Trytophane Complex.”Biochem. Biophys. Acta,112, 372–375.
Kotani, M.et al. 1955.Table of Molecular Integrals. Tokyo: Maruzen Co.
Liebman, P. A. 1962. “In Situ Microspectrophotometric Studies on the Pigments of Single Retinal Rods.”J. Biophys.,2, 161–178.
Mulliken, R. S. 1952. Molecular Compounds and Their Spectra: II.”J. Am. Chem. Soc.,74, 811–824.
Murrell, J. N. 1961. “Molecular Complexes and Their Spectra: IX. The Relationship Between the Stability of a Complex and the Intensity of its Charge-transfer Bands.”J. Am. Chem. Soc.,81, 5037–5043.
Pauling, L. C. 1960.The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry, 3rd Ed. Ithaca, N.Y.: Cornell University Press.
Person, W. B. 1963. “Electron Affinities of Some Halogen Molecules and the Chargetransfer Frequency.”J. Chem. Phys.,38, 109–116.
Pitt, G. A., J. D. Collins, R. A. Morton and P. Stok. 1955. “Studies on Rhodopsin.”J. Biochem.,59, 122–128.
Pullman, A. and B. Pullman. 1961. “The CIS-Trans Isomerization of Conjugated Polyenes and the Occurrence of a Hindered CIS-Isomere of Retinen in the Rhodopsin System”Proc. Nat. Acad. Sci., U.S.,47, 7–14.
Radding, C. M. and G. Wald. 1955–1956., “Acid-Base Properties of Rhodopsin and Opsin.”J. Gen. Physiol.,39, 909–922.
Schmidt, W. F. 1938. “Optical Polarization Analysis of a Protein-lipoid System, Illustrated by a Rod of the Retina.”Kolloid-Z,85, 137–148.
G. Wald and P. K. Brown. 1951–1952. “The Role of Sulfhydryl Groups In the Bleaching and Synthesis of Rhodopsin.”J. Gen. Physiol.,35, 797–821.
—. 1954. “On the Mechanism of the Visual Threshold and Visual Adaptation.”Science,119, 887–892.
— and R. Hubbard. 1960. “Enzymic Aspects of the Visual Processes.” InThe Enzymes, Vol. 3, 2nd Ed., P. D. Boyer and H. Lardy, Eds. New York: Academic Press, 369–386.
G. Wald. 1960. Proceedings XXIII International Congress of Physiological Sciences, Tokyo.
—, P. K. Brown and I. R. Gibbons. 1963. “The Problem of Visual Excitation.”J. Opt. Soc. Amer.,53, 20–35.
Yoshizawa, T. and G. Wald. 1963. “Pre-Lemirhodopsin and the Bleaching of Visual Pigments.”Nature,197, 1279–1286.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Galindo, I.G. A charge transfer process in the visual pigments. Bulletin of Mathematical Biophysics 29, 677–690 (1967). https://doi.org/10.1007/BF02476919
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02476919