title: X-ray fluorescence methods for investigations of lipid/protein membrane models.
abstract: The protective effect of the bisphosphonate drug xydiphone (K,Na-ethidronate) on membrane-bound enzyme damaged by lead ions has been studied. A protein/lipid film of Ca-ATPase/phosphatedylethanolamine deposited on a silicon substrate was used as a model system. The position of lead ions within the molecular film before and after the xydiphone treatment was determined using the total-reflection X-ray fluorescence method. This technique is based on the simultaneous measurement of the X-ray reflection and the yield of the fluorescence radiation excited by X-ray inelastic scattering. The possibility of directly locating lead ions is the main advantage of this approach. Xydiphone has been found to effectively eliminate lead ions that have been incorporated into Ca-ATPase molecules during a preliminary incubation in lead acetate solution. The lead ions that were bound at the sites of the Ca-ATPase attachment to the phospholipid monolayer have proved to be inaccessible for xydiphone. A preliminary incubation of Ca-ATPase in the xydiphone solution precluded the incorporation of lead ions into the protein.
authors.affiliation: Institute of Crystallography, Russian Academy of Sciences, Leninsky Pr. 59, Moscow 119333, Russia. nn_novikova@ns.crys.ras.ru
authors.forename: Natalia N
authors.initials: NN
authors.lastname: Novikova
authors.forename: Eleonora A
authors.initials: EA
authors.lastname: Yurieva
authors.forename: Svetlana I
authors.initials: SI
authors.lastname: Zheludeva
authors.forename: Michail V
authors.initials: MV
authors.lastname: Kovalchuk
authors.forename: Nina D
authors.initials: ND
authors.lastname: Stepina
authors.forename: Alla L
authors.initials: AL
authors.lastname: Tolstikhina
authors.forename: Ratmir V
authors.initials: RV
authors.lastname: Gaynutdinov
authors.forename: Dariya V
authors.initials: DV
authors.lastname: Urusova
authors.forename: Tatiana A
authors.initials: TA
authors.lastname: Matkovskaya
authors.forename: Alexandr M
authors.initials: AM
authors.lastname: Rubtsov
authors.forename: Olga D
authors.initials: OD
authors.lastname: Lopina
authors.forename: Alexsey I
authors.initials: AI
authors.lastname: Erko
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Konovalov
mesh_terms: D000252:Calcium-Transporting ATPases / Q000737:chemistry*; D012968:Etidronic Acid / Q000737:chemistry*; D007854:Lead / Q000032:analysis / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008567:Membranes, Artificial; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D013499:Surface Properties; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010714:Phosphatidylethanolamines; D007854:Lead; C483858:phosphatidylethanolamine; D000252:Calcium-Transporting ATPases; D012968:Etidronic Acid