1. Photoinduced generation of electric current by bacteriorhodopsin, incorporated into the planar phospholipid membrane, has been directly measured with conventional electrometer techniques. 2. Two methods for bacteriorhodopsin incorporation have been developed: (a) formation of planar membrane from a mixture of decane solution of phospholipids and of the fraction of violet fragments of the Hal...

The retinylidene chromophore mutant (Y185F) of bacteriorhodopsin, in which Tyr-185 is substituted by phenylalanine, is examined and compared with wild-type bacteriorhodopsin expressed in Escherichia coli; both were reinstituted similarly in vesicles. The Y185F mutant shows (at least) two distinct spectra at neutral pH. Upon light absorption, the blue species (which absorbs in the red) behaves a...

The retinal-protein complex bacteriorhodopsin mediates lightxnergy conversion in halobacteria. This chromoprotein is embedded in the cell membrane and forms insular regions. These can be isolated by membrane-fractionation procedures, and they consist of a lipid matrix containing bacteriorhodopsin molecules in a hexagonal crystalline arrangement called the purple membrane. Light-absorption by ba...

Rhodopsins possess retinal chromophore surrounded by seven transmembrane α-helices, are widespread in prokaryotes and in eukaryotes, and can be utilized as optogenetic tools. Although rhodopsins work as distinctly different photoreceptors in various organisms, they can be roughly divided according to their two basic functions, light-energy conversion and light-signal transduction. In microbes, ...

Sensory rhodopsin I (SRI) is one of the most interesting photosensory receptors in nature because of its ability to mediate opposite signals depending on light color by photochromic one-photon and two-photon reactions. Recently, we characterized SRI from eubacterium Salinibacter ruber (SrSRI). This protein allows more detailed information about the structure and structural changes of SRI during...

The light-driven proton pump, bacteriorhodopsin (bR), in Halobacterium salinarum carries out its function proceeding through intermediates named J, K, L, M, N, and O (for recent reviews see [1, 2]). To understand the molecular mechanism of light-energy transduction many methods are used [3]. One of them, photoexcitation of the intermediates, provides valuable information on their particular rôl...

The purple membrane is a two-dimensional crystalline lattice formed by bacteriorhodopsin and lipid molecules in the cytoplasmic membrane of Halobacterium salinarum. High-resolution structural studies, in conjunction with detailed knowledge of the lipid composition, make the purple membrane one of the best models for elucidating the forces that are responsible for the assembly and stability of i...

Homogenous bacteriorhodopsin-DPPC proteoliposomes were characterized and used as a target for the general anesthetic Enflurane. Dose–response curves for the protein and the lipids, in the very same sample, at high (2800) and low (360) lipid: bacteriorhodopsin molar ratios, were compared simultaneously. Above the main phase transition temperature of DPPC, there is no difference between the prote...

Bacteriorhodopsin (BR) is a retinal protein that is a light-driven proton pump and has an important role in photosynthesis in archaebacterium Halobacterium salinarum. The BR molecule absorbs light and photochemical changes occur in it, and different intermediates will be produced in its photochemical cycle that some of them like P and Q intermediates have a long half-life. There have been many ...

We theoretically and experimentally analyze the formation of thick Purple Membrane (PM) polyacrylamide (PA) films by means of optical spectroscopy by considering the absorption of bacteriorhodopsin and scattering. We have applied semiclassical quantum mechanical techniques for the calculation of absorption spectra by taking into account the Fano effects on the ground state of bacteriorhodopsin....