SOLID-PHASE SYNTHESIS OF DNA FRAGMENTS CONTAINING THE MODIFIED BASE 7-HYDRO-8-OXO-2'-DEOXYGUANOSINE

The 5'-(4,4'-dimethoxytrityl) protected 3'-(2-cyanoethoxy)-N,N-diisopropylphosphoramidite of 7-hydro-8-oxo-2'-deoxyguanosine, the exocyclic amino and lactam functions of which are protected with acetyl and diphenylcarbamoyl groups, respectively, has been prepared from the 8-bromo derivatives of deoxy-and riboguanosine. This synthon, in combination with standard d-nucleoside 3'-(2-cyanoethoxy)-N,N-diisopropylphosphoramidites, was applied successfully to a solid-phase synthesis. Well-defined oligodeoxyribonucleotides containing a 7-hydro-8-oxo-2'-deoxyguanosine residue at predetermined positions were obtained after deprotection with methanolic ammonia and purification by gel filtration.