title: Combination of extended X-ray absorption fine structure spectroscopy with lipidic cubic phases for the study of cation binding in bacteriorhodopsin.
abstract: We have performed a quantitative X-ray absorption fine structure analysis of bacteriorhodopsin in purple membrane patches and in lipidic cubic phases regenerated with Mn(2+). Lipidic cubic phases and purple membrane results have been compared, demonstrating that the lipidic cubic phase process does not introduce relevant distortions in the local geometry of the cation binding sites. For both samples, we have observed similarities for Mn(2+) coordination in terms of type, number, and average distances of surrounding atoms, indicating a first coordination shell composed by 6 O atoms, and 3/4 C atoms located in the second coordination shell.
authors.affiliation: Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular and Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, Bellaterra, Spain. peralvarezmarin@gmail.com
authors.forename: Alex
authors.initials: A
authors.lastname: Perálvarez-Marín
authors.forename: Francesc
authors.initials: F
authors.lastname: Sepulcre
authors.forename: Mercedes
authors.initials: M
authors.lastname: Márquez
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Proietti
authors.forename: Esteve
authors.initials: E
authors.lastname: Padrós
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002413:Cations, Divalent / Q000737:chemistry*; D019617:Halobacterium salinarum / Q000737:chemistry / Q000378:metabolism; D008055:Lipids / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D008565:Membrane Proteins; D018717:Purple Membrane / Q000737:chemistry* / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy / Q000295:instrumentation*
chemical_list: D001426:Bacterial Proteins; D002413:Cations, Divalent; D008055:Lipids; D008565:Membrane Proteins; D008345:Manganese; D001436:Bacteriorhodopsins