Halobacterium halobium purple membrane

Halobacterium halobium purple membrane/bacteriorhodopsin Mitochondrial Fi-ATPase... 

ITowever, membrane proteins can also be distributed in nonrandom ways across the surface of a membrane. This can occur for several reasons. Some proteins must interact intimately with certain other proteins, forming multisubunit complexes that perform specific functions in the membrane. A few integral membrane proteins are known to self-associate in the membrane, forming large multimeric clusters. Bacteriorhodopsin, a light-driven proton pump protein, forms such clusters, known as purple patches, in the membranes of Halobacterium halobium (Eigure 9.9). The bacteriorhodopsin protein in these purple patches forms highly ordered, two-dimensional crystals. 

Phospholipids in purple membrane of Halobacterium Silica gel G halobium Note H = hexane, D = diethyl ether, F = formic acid, BuOH = butanol. 23... 

Ethanol and choline glycerolipids were isolated from calf brain and beef heart lipids by PTLC using silica gel H plates. Pure ethanol amine and choline plasmalogens were obtained with a yield of 80% [74]. Four phosphohpid components in the purple membrane (Bacteriorhodopsin) of Halobacterium halobium were isolated and identified by PTLC. Separated phosphohpids were add-hydrolyzed and further analyzed by GC. Silica gel G pates were used to fractionate alkylglycerol according to the number of carbon atoms in the aliphatic moiety [24]. Sterol esters, wax esters, free sterols, and polar lipids in dogskin hpids were separated by PTLC. The fatty acid composition of each group was determined by GC. 

Henderson, R., The purple membrane from Halobacterium halobium, Ann. Rev. Biophys. Bioeng., 6, 87 (1977). 

Ordered arrangements of proteins in membranes in vivo With the exception of the purple membrane produced by Halobacterium halobium, the order discussed in this section does not involve an exact regular geometrical structure. However, membrane bound enzymes and structure proteins associated with membranes are arranged in ways which are clearly defined and which involve definite and regular interactions between different kinds of molecule. Only thus can they carry out... 

Bacteriorhodopsin, is a retinal-containing protein in the purple membrane of a halophilic, (salt-loving) archaebacterium, Halobacterium halobium, which pumps protons out of the cell on activation by light.The three-dimensional structure of bacteriorhodopsin resembles that of rhodopsin in the eye. 

Bacteriorhodopsin, a light-driven proton pump, is a large (27000 Dalton) membrane protein, located in the purple membrane of halobacterium halobium (for a recent review see Lanyi, 1993). It spans the membrane by seven-a-helices (see Fig 6.6-7). The chro-mophore retinal is embedded inside the protein, shielded by the helices. Retinal connects to the Lys 216 of the protein via a protonated Schiff s base (Fig. 6.6-7). 

This approach has been extended by Rupley et al. (1988) to study of the water-induced percolation in hydrated purple membrane fragments of Halobacterium halobium. The results and conclusions are qualitatively similar to those reported above for lysozyme. (1) The percolation is two-dimensional, judged by the value of the critical exponent (Fig. 15). (2) Certain regions of the surface provide preferred protonic conduction paths. (3) There is a correspondence between the onset of function—here, the photoresponse—and the establishment of long-range connectivity within the surface water clusters. 

The purple membrane of Halobacterium halobium was discovered in the late 1960 s when Stoeckenius and co-workers described sheet-like structures which could... 

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