title: Changes in the protonation state of bacterio-opsin during reconstitution of bacteriorhodopsin.
abstract: Protonation changes of the protein occur during the reconstitution of bacteriorhodopsin from bacterio-opsin and all-trans retinal in the purple membrane of Halobacterium halobium. The protonation changes are conveniently determined from measures of the pH changes after photoisomerisation of 9-cis retinal in apomembrane preparations, which induces the reconstitution. In addition, to the omega-amino group of the lysine which is involved in the condensation of retinal and bacterio-opsin, the dissociation equilibria of at least two other amino acid residues are changed during the reconstitution. The results are consistent with a proposed model of chromophore structure in which an interaction of the Schiff's base occurs with two protonable amino acid residues.
mesh_terms: D001059:Apoproteins; D001436:Bacteriorhodopsins / Q000528:radiation effects; D002338:Carotenoids / Q000528:radiation effects; D055598:Chemical Phenomena; D002621:Chemistry; D004224:Diterpenes; D006217:Halobacterium; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D008027:Light; D008956:Models, Chemical; D011522:Protons; D012172:Retinaldehyde / Q000528:radiation effects; D014466:Ultraviolet Rays; D014801:Vitamin A / Q000031:analogs & derivatives
chemical_list: D001059:Apoproteins; D004224:Diterpenes; D011522:Protons; D014801:Vitamin A; D002338:Carotenoids; C031338:13-cis-retinal; C031390:9-cis-retinal; D001436:Bacteriorhodopsins; C017827:bacterio-opsin; D012172:Retinaldehyde