THE STRUCTURE OF 3'-O-ANTHRANILOYLADENOSINE, AN ANALOG OF THE 3'-END OF AMINOACYL-TRANSFER-RNA

3'-O-Anthraniloyladenosine, an analogue of the 3'-terminal aminoacylad enosine residue in aminoacyl-tRNAs, was prepared by chemical synthesis , and its crystal structure was determined, The sugar pucker of 3'-O-a nthraniloyladenosine is 2'-endo resulting in a 3'-axial position of th e anthraniloyl residue, The nucleoside is in syn conformation, which i s stabilized by alternating stacking of adenine and benzoyl residues o f the neighboring molecules in the crystal lattice, The conformation o f the 5'-hydroxymethylene in 3'-O- anthraniloyladenosine is gauche-gau che. There are two intramolecular and two intermolecular hydrogen bond s and several H-bridges with surrounding water molecules, The predomin ant structure of 3'-O-anthraniloyladenosine in solution, as determined by NMR spectroscopy, is 2'-endo, gauche-gauche and anti for the sugar ring pucker, the torsion angle around the C4'-C5' bond and the torsio n angle around the C1'-N9 bond, respectively, The 2'-endo conformation of the ribose in 2'(3')-O-aminoacyladenosine, which places the adenin e and aminoacyl residues in equatorial and axial positions, respective ly, could serve as a structural element that is recognized by enzymes that interact with aminoacyl-tRNA or by ribosomes to differentiate bet ween aminoacylated and non-aminoacylated tRNA.