Investigation of spectral and kinetic properties of polymer films based on some analogs of bacteriorhodopsin.

We investigated the characteristics of modified forms of bacteriorhodopsin in which the native retinal chromophore is replaced by a chemical analog ("bacteriorhodopsin analogs"), embedded in a polymer film. We found they displayed differential absorption spectra and kinetic curves for the most long-lived intermediates of the BR photocycle. We also studied the influence of chemical reagents on the functioning of bacteriorhodopsin analogs in polymeric films. We found that the immobilization of BR analogs in polymer leads, as in the case of native BR, to a slowing down of their photocycles. Kinetic analysis showed that M-like state intermediates of all the BR analogs have a longer dark relaxation time than native BR. The retention and retardation of the photocycle in these films suggest that films based on BR analogs can be used as photochromic materials. Moreover, 4-keto BR seems to be more promising for this application as compared not only with native BR, but also with other analogs of BR studied in this work.