Comparison of Bacteriorhodopsin Conformational Changes with Uniaxially Elongated Aliphatic Polyamide Samples by Using FT-IR Difference Spectroscopy

Abstract

FT-IR difference spectra for the photoreactions of bacteriorhodopsin (bR) are compared to difference spectra of polyamide-6 and -11 obtained during uniaxial elongation. The purple membrane was hydrated with D2O in order to identify bands above 3000 cm(-1) In the bR photocycle(bR --> K), the difference spectra in D2O closely march the band contour found in the difference spectra of elongated polyamide-11. The data suggest that a structural change occurs in the backbone of the membrane protein bacteriorhodopsin, resulting in weakened and strengthened hydrogen bonds of the amide functionality of the backbone.