Figure 2.
(A) Example of the quality of the final Fourier (2Foo-Fcc) sum electron density (∼1.2 σ threshold). (B) Overall view of RNA13 duplexes in the unit cell. Residues in the four strands are numbered from 101–113, 201–213, 301–313 and 401–413, respectively. Carbon atoms of strands 1, 2, 3 and 4 are colored in beige, pink, salmon and gray, respectively, and red, blue and orange mark oxygen, nitrogen and phosphorus atoms, respectively. Strontium ions are shown as orange spheres and smaller spheres in cyan represent water molecules. The carbon atoms in the amide carbonyls and the adjacent linking carbon atoms are colored in green and the C-NH-CO-C linkages are highlighted in ball and stick mode.