The structure of the ribodinucleoside monophosphate guanylyl‐3',5'‐cytidine as its ammonium octahydrate salt

Abstract

The crystal and molecular structure of an ammonium octahydrate salt of the ribodinucleoside monophos-phate guanylyl-3',5'-cytidine (CIgH24NsOI2P) has been determined by X-ray methods, and refined to a final R of 0.111 for 1197 observed reflections. The salt crystallizes in space group C2 with cell dimensions a -- 20.987 (6), b = 16.470 (4), c = 9.566 (1) fit and fl = 94.36 (2)°; Z = 4 for a calculated density of 1.50 Mg m -3 and #(Cu Ka) = 1.19 mm -1. The unit-cell dimensions are very similar to those of the sodium salt [Rosenberg, Seeman, Day & Rich (1976). J. Mol. Biol. 104, 145-167]; however, the two structures are non-isomorphous. Conformational features of the ammonium salt are as expected for an RNA-like Watson-Crick base-paired duplex.