Nonlinear absorbance effects in bacteriorhodopsin

George W. Rayfield

doi:10.1117/12.45121

1 March 1991 Nonlinear absorbance effects in bacteriorhodopsin

George W. Rayfield

Proceedings Volume 1436, Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films; (1991) https://doi.org/10.1117/12.45121
Event: Optics, Electro-Optics, and Laser Applications in Science and Engineering, 1991, Los Angeles, CA, United States

Abstract

Bacteriorhodopsin (BR) is a protein found in the cell membrane wall of Halobacterium halobium and serves as a light-activated proton pump (i.e., the protein converts light energy into chemical energy). The chromophore (retinal) responsible for light absorption is located within a pocket of the opsin and is bound via a Schiff base to a lysine residue in the amino acid sequence. When BR is illuminated by a laser light flash, transient changes occur in the visible absorption spectrum of the protein -- i.e., the material is photochromic. The optical absorption changes are characterized by a series of photointermediates, with characteristic rise and fall times that range from less than a picosecond to more then 10 milliseconds. This photochromic property of BR makes it a useful material for optical devices. With an aim toward developing an optical switch for the Army, we are studying the transient absorption of nanosecond light pulses from a dye laser in the spectral region in which the absorbance of BR increases as light intensity increases. This nonlinear effect is wavelength-dependent and becomes a bleach in a different spectral window. The nonlinear absorption change is reversible.

Citation Download Citation

George W. Rayfield "Nonlinear absorbance effects in bacteriorhodopsin", Proc. SPIE 1436, Photochemistry and Photoelectrochemistry of Organic and Inorganic Molecular Thin Films, (1 March 1991); https://doi.org/10.1117/12.45121

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