RESUMEN
The crystal structure of superprotonic conductor caesium hydrogen sulfate phosphate [Cs4(HSO4)3(H2PO4)] have been analyzed using neutron diffraction methods. Additionally, its structure and surface layers have been investigated using atomic force microscopy. From the diffraction data obtained, Fourier syntheses of neutron scattering densities were calculated, and the localization of hydrogen atoms and the parameters of three types of hydrogen bonds in the crystal structure were accurately determined. Correlation of surface characteristics of samples obtained by atomic force microscopy with their crystal structure is shown.
RESUMEN
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.