Characterization of two pterin derivatives isolated from Methanoculleus thermophilicum

Methanoculleus thermophilicum was shown to contain two pterin derivatives. The structures of these pterin derivatives were established from amino acid analysis, 1 H‐NMR and fast‐atom bombardment mass spectrometry data. One of the pterins was identified as tatiopterin‐O, an aspartyl derivative of methanopterin with a proton at position 7 of the pterin moiety. The other pterin, which we named thermopterin, differed in the structure of the aniline group, containing two additional hydroxyl residues. The IUPAC name of thermopterin is N ‐[‐1′‐(2"‐amino‐4"‐hydroxy‐6"‐pteridinyl)ethy]‐4‐[2′,3′,4′,5′,‐tetrahydroxypent‐1′‐yl(5′→ 1")O‐α‐ribofuranosyl‐5"‐phosphoric acid]‐2,5‐dihydroxyaniline, in which the phosphate group is esterified with α‐hydroxyglutarylaspartic acid.