TRIFURCATED (4-CENTER) HYDROGEN-BOND IN SOLID-STATE CRYSTAL-STRUCTUREOF 5'-AMINO-5'-DEOXYADENOSINE P-TOLUENESULFONATE

The crystal structure of 5'-amino-5'-deoxyadenosine (5'-Am.dA) p-tolue nesulfonate has been determined by X-ray crystallographic methods. It belongs to the orthorhombic space group P2(1)2(1)2(1) with a = 7.754(3 )Angstrom, b = 8.065(1)Angstrom and c = 32.481(2)Angstrom. This nucleo side side shows a syn conformation about the glycosyl bond and C2'-end o-C3'-exo puckering for the ribose sugar. The orientation of N5' atom is gauche-trans about the exocyclic C4'-C5' bond. The amino nitrogen N 5' forms a trifurcated hydrogen bond with N3, O9T and O4' atoms. Adeni ne bases form A.A.A triplets through hydrogen bonding between N6, N7 a nd N1 atoms of symmetry related nucleoside molecules.