Structure of an amniotic fluid component, 7-(4,5-cis-dihydroxy-1-cyclopenten-3-ylaminomethyl)-7-deazaguanine (queuine), a substrate for tRNA: guanine transglycosylase.

A compound present in bovine amniotic fluid, and which is a substrate for tRNA:guanine transglycosylase, has been structurally characterized as queuine, a hypermodified base which occurs in transfer RNA. The structure assignment is based on mass spectrometry, proton nuclear magnetic resonance, and ultraviolet absorbance data.