Heterogeneity based on bending of purple membrane containing bacteriorhodopsin

Abstract

The first and second derivatives of dielectric spectra have evidenced the existence of two interacting states of purple membrane (PM) that respond differently to the intensity of illuminating light providing, this way, underlying consequences to the heterogeneous behavior of bacteriorhodopsin (bR). It is of particular interest to note that the rotational diffusion coefficient of PM has exhibited non-linearity versus light intensity. The explored non-linearity in electrical properties beers, thereby, on changes in PM size. The non-linear variations in PM bending might initiate, in consequence, variations in the dipole moment (permanent and induced) and dc-conductivity of PM patches. Proposal based on PM bending has been introduced to correlate the light intensity effect to the PM lipid environment. Modulation of the global structure of PM and, in turn, its electrical properties by an external perturbation (e.g., light) could be of interest in biotechnological applications based on optoelectronic properties of bR.

An Apparent General Solution for the Kinetic Models of the Bacteriorhodopsin Photocycles

“…5 Heterogeneity of BR is strongly indicated in items 1, 5, 6, 9, and 10 listed just above. Further evidence has been obtained in retinal binding studies, 52 studies of changes in dielectric spectroscopy as a function of light intensity, 53 and the finding of two bands in the isoelectric focusing profile obtained from a highly purified purple membrane preparation. 54 Examples of different photocycles operating under different conditions are well documented by all ten citations in the list directly above.…”