Structure determination of two new amino acid-containing derivatives of adenosine from tRNA of thermophilic bacteria and archaea

Two new nucleosides have been identified in unfractionated transfer RNA of two thermophilic bacteria, Thermodesulfobacterium commune, and Thermotoga maritima, six hyperthermophilic archaea, including Pyrobaculum islandicum, Pyrococcus furiosus and Thermococcus sp. and two mesophilic archaea, Methanococcus vannielii and Methanolobus tindarius. Structures were determined primarily by mass spectrometry, as 3-hydroxy-N-[[(9-beta-D-ribofuranosyl-9H-purin-6- yl)amino]carbonyl]norvaline, (hn6A), structure 1, and 3-hydroxy-N-[[(9-beta-D-ribofuranosyl-9H-2-methylthiopurin-6- yl)amino]carbonyl]norvaline (ms2hn6A), 2. The amino acid side chain was characterized as 3-hydroxynorvaline (3) by gas chromatography-mass spectrometry of the trimethylsilyl derivative after cleavage from 1 and 2 by alkaline hydrolysis. Evidence for the amino acid-purine carbamoyl linkage was obtained from the collision-induced dissociation mass spectrum of trimethylsilylated 1, and the total structure was confirmed by chemical synthesis of 1.