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.

Some factors affecting the process of photoinduced hydroxylaminolysis in different bacteriorhodopsin-based media.

This review presents the results of studies concerning some factors that affect the process of photoinduced hydroxylaminolysis (PHA) in bacteriorhodopsin (BR) and different BR-based media. We consider the peculiar properties of the PHA reaction in water suspensions of BR and BR-based media depending on variation in PHA ingredients, and in particular the use of O-substituted hydroxylamines instead of hydroxylamine hydrochloride. In addition, we discuss how such factors as preliminary ultra-sonication affect the reaction of PHA in the course of BR bleaching and following the reconstitution of bacterioopsin.

Preliminary ultrasonication affects the rate of the bacteriorhodopsin bleaching and the effectiveness of the reconstitution process in bacterioopsin.

The formation process of polymer films based on bacteriorhodopsin (BR) analogs requests a high amount of BR samples one time only. The common technique for apomembrane formation (preparation of bacterioopsin, BO) is not designed to be operated with high concentrations and high volumes of BR, so the use of this technique results in a low rate of BR bleaching. To accelerate the process of BR bleaching preliminary sonication was used.

Peculiar properties of photoinduced hydroxylaminolysis in different bacteriorhodopsin-based media using O-substituted hydroxylamines.

The process of photoinduced hydroxylaminolysis has been re-examined in different bacteriorhodopsin (BR)-based media using O-substituted hydroxylamines, in particular, O-(4-nitrobenzyl) hydroxylamine hydrochloride (NBHA), O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride (FBHA) and O-(t-butyl) hydroxylamine hydrochloride (BHA). Both wild type (WT) and D96N BR-based gelatine films and gels were studied. The expected increase in the bleaching rate of BR in gelatin films by using O-substituted hydroxylamines in place of HA was not achieved.

Optical characteristics of polymer films based on bacteriorhodopsin for irreversible recording of optical information.

Bacteriorhodopsin (BR)-containing polymer films have been developed in which photoinduced transformations of BR molecules take place during the process of photoinduced hydroxylaminolysis (PHA). The routine simplified scheme of the phototransformation is B <--> M(412) in the case of polymer films based on nonmodified BR. In the case of polymer films based on BR modified by hydroxylamine (HA), this scheme is changed to [formula in text] where retinal oxime (RO) is a final product of chemical trapping of retinal by the HA molecule.

Photochromic polymer films based on a 14-F bacteriorhodopsin derivative.

Spectral and kinetic characteristics were measured for polymer (gelatin) films based on 14-F bacteriorhodopsin (BR), both wild-type (WT) and D96N mutant, to study the peculiarities of photo-induced transformation of the samples. It was demonstrated earlier that incorporation of 14-F retinal into the apomembrane of both 14-F WT and 14-F D96N produces pigments with drastically different photo-induced behavior, regarding the formation and decay of a red-shifted species at 660 nm. However, similar fundamental differences between 14-F WT and 14-F D96N, if embedded into gelatin matrix, were not observed.

Effect of dehydration on photoinduced transformation in gelatin films made with 14-fluoro bacteriorhodopsin derivatives.

Photoinduced transformation in gelatin films made with 14-fluoro bacteriorhodopsin derivatives, both wild-type (WT) and D96N mutant, were studied. Spectral and kinetic peculiarities for these two types of samples were compared over a wide range of relative humidity (9-92%). Analysis of the results considered two existing photoinduced processes that occur in suspensions and films of corresponding pigments.