Refinement of the crystal structure of adenosine-5'-phosphate

Abstract

The crystal structure of adenosine-5'-phosphate has been determined by three-dimensional Patter-son superposition and two-dimensional Fourier methods. It has been refined by full-matrix least-squares computations to a final R factor of 6"8% for 1197 reflections with measurable intensities. The space group is P21, with unit cell dimensions of a = 12.77, b = 11.82, c = 4.882 A and fl = 92 ° 24'. The locations of 11 out of 16 hydrogen atoms in the asymmetric unit have been determined by difference-Fourier syntheses and least-squares refinement. The adenine ring is essentially unchanged from adenine hydrochloride, though it is slightly non-planar, probably owing to packing forces. The N-glycosidic bond is bent about 8 ° out of the adenine plane. Atom C3' of the ribose ring is 0.66 A out of the plane of the remaining four atoms. The relative orientation of the adenine and ribose groups is anti, with ~CN-18 °. Certain generalities are suggested concerning the structure of organic phosphate groups.