The very same molecule bacteriorhodopsin consists of seven are in the conformation of a-helix segments running through the entire thickness of the cell membrane in a direction perpendicular to its plane. This fact allowed to apply direct physical methods to study the spatial structure of bacteriorhodopsin in the membrane. Combination of electron microscopy and diffraction methods for the analysis was determined the molecular structure of the protein conformation in the form of alpha-helix. The hydrophobic domains are transmembrane segments, and hydrophilic domains protrude from the membrane and connects the individual a-helical vnutrimembrannye strands of protein molecules. These speakers at the surface of the lipid layer domains in the molecule of bacteriorhodopsin revealed 4.
In the cell membranes of halophilic bacteria bacteriorhodopsin functions as a proton pump svetozavisimogo, creating a gradient of hydrogen ions, whose energy is used by the cell to synthesize adenosine triphosphate (ATP). The mechanism of ATP synthesis is called "beshlorofilny photosynthesis." In response to the absorption of a photon bleached bacteriorhodopsin VR548, entering the cycle of photochemical transformations, as a result of is between the inner and outer sides of the membrane concentration gradient of protons established. Education concentration gradient of protons leads to the fact that the illuminated cells synthesize ATP. Thus there is reversible isomerization of retinal to trans-BR548 retinal BR568, initiating a cascade of chemical reactions, followed by separation of protons from the protein molecule and its joining of the cytoplasm. This process is reversible in the dark proceeds in the opposite direction. One of the spectral forms of bacteriorhodopsin with the absorption maximum at 412 nm (M412) has a deprotonated aldiminnoy relationship between residual retinal and protein.
