Abstract
Electric field-induced absorption changes of bacteriorhodopsin were studied with different samples of purple membranes which were prepared as randomly oriented and electrically oriented films of purple as well as cation-depleted blue bacteriorhodopsin. The absorption changes were proportional to the square of the field strength up to ≈300 kV/cm. The electric field from the intracellular side to the extracellular side of the purple bacteriorhodopsin induces a spectrum change, resulting in a spectrum similar to that of the cation-depleted blue bacteriorhodopsin. When the field was removed, the purple state was regenerated. The blue state was mainly affected by an electric field in the opposite direction, suggesting a reversible interaction with the Schiff's base bond of the retinal. Since the field-induced reaction of bacteriorhodopsin was observed in the presence of a concomitant steady ion flux, it is assumed that the generation of a local diffusion potential may play an important role in these spectral reactions. Although the fragments were fixed in the dried film, electric dichroism was observed. The dichroic contribution of the total absorbance change was about 15%. The angular displacement of the retinal transition moment was calculated to be 1.5° toward the membrane normal.
Similar content being viewed by others
References
Borisevitch GP, Lukashev EP, Kononenko AA, Rubin AB (1979) Bacteriorhodopsin (BR570) bathochromic band shift in an external field. Biochim Biophys Acta 546:171–174
Chamorovsky SK, Lukashev EP, Kononenko AA, Rubin AB (1983) Effects of electric field on the photocycle of bacteriorhodopsin. Biochim Biophys Acta 725:403–406
Chang C-H, Chen J-G, Govindjee R, Ebrey T (1985) Cation binding by bacteriorhodopsin. Proc Natl Acad Sci USA 82:396–400
Eigen M, De Maeyer L (1963) Relaxation methods. In: Weissberger A (ed) Technique of organic chemistry, Vol VIII, Part II John Wiley and Sons, New York, pp 988–1001
Fisher K, Yanagimoto K, Stoeckenius W (1978) Oriented adsorption of purple membrane to cations surfaces. J Cell Biol 77:611–620
Fredericq E, Houssier C (1973) Electric dichroism and electric birefringence. Clarendon Press, Oxford
Hess B (1978) In: Lefever R (ed) Molecular movements and chemical reactivity. John Wiley and Sons, New York, pp 226–227
Heyn MP, Cherry RJ, Müller U (1977) Transient and linear dichroism studies on bacteriorhodopsin: Determination of the orientation of the 568 nm all-trans retinal chromophore. J Mol Biol 117:607–620
Kahn LD, Shu-Itu (1984) Electric birefringence study of the purple membrane of Halobacterium halobium. Biopolymers 23:707–718
Keszthelyi L (1980) Orientation of membrane fragments by electric field. Biochim Biophys Acta 598:429–436
Kimura Y, Ikegami A, Ohno K, Saigo S, Takeuchi Y (1981) Electric dichroism of purple membrane suspensions. Photochem Photobiol 33:435–439
Kimura Y, Fujiwara M, Ikegami A (1984a) Anisotropic electric properties of purple membrane and their change during the photocycle. Biophys J 45:615–625
Kimura Y, Ikegami A, Stoeckenius W (1984b) Salt and pH-dependent changes of the purple membrane absorption spectrum. Photochem Photobiol 40:641–646
Kohl K-D, Engelhard M, Hess B (1984) Specific requirement of cations for the photocycle of bacteriorhodopsin (bR). EBEC Rep 3B:647
Korenstein R, Hess B (1977a) Hydration effects on cis-trans isomerization of bacteriorhodopsin. FEBS Lett 82:7–11
Korenstein R, Hess B (1977b) Hydration effects on the photocycle of bacteriorhodopsin in the thin layers of purple membrane. Nature 270:184–186
Korenstein R, Hess B (1978) Immobilization of bacteriorhodopsin and orientation of its transition moment in purple membrane. FEBS Lett 89:15–20
Korenstein R, Hess B (1982) Analysis of photocycle and orientation in thin layers. Methods Enzymol 88:180–193
Lukashev EP, Vozary E, Kononenko AA, Rubin AB (1980) Electric field promotion of the bacteriorhodopsin BR570 to BR412 photoconversion in films of Halobacterium halobium purple membranes. Biochim Biophys Acta 592:258–266
Oesterhelt D, Hess B (1973) Reversible photolysis of the purple complex in the purple membrane of Halobacterium halobium. Eur J Biochem 37:316–326
Oesterhelt D, Stoeckenius W (1974) Isolation of the cell membrane of Halobacterium halobium and its fractionation into red and purple membrane. Methods Enzymol 31A:667–678
Shinar R, Druckmann S, Ottolenghi M, Korenstein R (1977) Electric field effects in bacteriorhodopsin. Biophys J 19:1–5
Stoylov SP, Todorov G, Zhirkov A (1984) Effect of external electric fields on membrane proteins—the bacteriorhodopsin. Bioelectron Bioenerg 12:49–55
Todorov G, Sokerov S, Stoylov SP (1982) Interfacial electric polarizability of purple membranes in solution. Biophys J 40:1–5
Tsuji K, Rosenheck K (1979) Electric dichroism of purple membrane. In: Jennings BR (ed) Elektro-optics and dielectrics of macromolecules and colloids. Plenum Press, New York, pp 77–88
Tsuji K, Neumann E (1981a) Structural changes in bacteriorhodopsin induced by electric impulses. Int J Biol Macromol 3:231–242
Tsuji K, Neumann E (1981b) Electric-field induced pK changes in bacteriorhodopsin. FEBS Lett 128:265–268
Tsuji K, Neumann E (1983) Conformational flexibility of membrane proteins in electric fields I. Ultraviolet absorbance and light scattering of bacteriorhodopsin in purple membranes. Biophys Chem 17:153–163
Váró Gy (1981) Dried oriented purple membrane samples. Acta Biol Acad Sci Hung 32:301–310
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tsuji, K., Hess, B. Electric field induced conformational changes of bacteriorhodopsin in purple membrane films. Eur Biophys J 13, 273–280 (1986). https://doi.org/10.1007/BF00254209
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00254209