THE IDENTIFICATION OF HYDROXYMETHYLURACIL IN DNA OF TRYPANOSOMA-BRUCEI

We have previously reported the detection of two unusual nucleotides, pdJ and pdV, in the DNA of Trypanosoma brucei (Gommers-Ampt et al., 19 91). pdJ was found to be a novel nucleotide and is possibly involved i n the regulation of variant specific surface antigen gene expression i n trypanosomes. Recent evidence suggests that V could be a precursor o f J, making V a key compound in the study of the biosynthesis and func tion of J. We have therefore determined the structure of V and here we present proof that V is HOMeU. The identity is based on a detailed co mparison of dV(p) with authentic HOMedU(p), showing: I) co-migration i n three different liquid chromatography analyses II) identical UV abso rbance characteristics III) identical behavior in acetyl-pentafluorobe nzyl derivatization and subsequent Gas chromatography/Mass spectrometr y (GC/MS). The GC/MS technique has not been used before to analyse HOM edU purified from biological material. Because of its high sensitivity , it may also be useful for the detection of the low amounts of HOMedU resulting from oxidative damage of DNA.