PROTON NUCLEAR-MAGNETIC-RESONANCE MEASUREMENTS OF 2'-AMINODEOXYURIDYLYL-3', 5'-DEOXYURIDINE

A dideoxyribonucleotide, 2'-amino-2'-deoxyuridylyl 3',5'-deoxyuridine, containing an unsual base (2'-amino-2'-deoxyuridine) that is resistan t to nucleases was investigated by H-1 NMR. The pK(a) of the protonati on of the amino group (5.8) was determined by profiles of chemical shi fts of protons in the vicinity of amino group versus pH. However, prot onation of the amino group has little effect on the conformation of th e dimer, assumed to be B-form DNA. This conclusion is drawn from the c hemical shift data and coupling constants of H-1'-H-2'. Thus, 2'-amino -2'-deoxyuridine can be used in antisense and anticode oligonucleotide s.