Detection of alkali metal ions in DNA crystals using state-of-the-art X-ray diffraction experiments.

ABSTRACT: The observation of light metal ions in nucleic acids crystals is generally a fortuitous event. Sodium ions in particular are notoriously difficult to detect because their X-ray scattering contributions are virtually identical to those of water and Na(+.)O distances are only slightly shorter than strong hydrogen bonds between well-ordered water molecules. We demonstrate here that replacement of Na(+) by K(+), Rb(+) or Cs(+) and precise measurements of anomalous differences in intensities provide a particularly sensitive method for detecting alkali metal ion-binding sites in nucleic acid crystals. Not only can alkali metal ions be readily located in such structures, but the presence of Rb(+) or Cs(+) also allows structure determination by the single wavelength anomalous diffraction technique

SUBMITTER: Tereshko V 

PROVIDER: S-EPMC29719 | biostudies-literature | 2001 Mar

REPOSITORIES: biostudies-literature