Stereochemistry of nucleic acids and their constituents. IX. The conformation of the antibiotic puromycin dihydrochloride pentahydrate.

The elucidation of puromycin structure represents the first case where both a nucleic acid and a protein fragment are found together in a crystal. The molecule displays an elongated conformation with the nucleoside and the p-methoxy-L-phenylalanine in the preferred conformation. The purine and the tyrosine rings form alternating stacks with interplanar spacings of 3.4 A. The inhibitory effect of this antiobiotic may be due, in part, to its unique conformation and the ability of the amide proton on N(3') to hydrogen bond to the active site of the ribosomal enzyme, peptide synthetase.