Increased DNA binding and sequence discrimination of PNA oligomers containing 2,6-diaminopurine

The synthesis of a diaminopurine PNA monomer, N[N-6-(benzyloxycarbonyl)-2,6-diaminopurine-9-yl] acetyl-N-(2-t-butyloxycarbonylaminoethyl)glycine, and the incorporation of this monomer into PNA oligomers am described, Substitution of adenine by diaminopurine in PNA oligomers increased the T-m of duplexes formed with complementary DNA, RNA or PNA by 2.5-6.5 degrees C per diaminopurine, Furthermore, discrimination against mismatches facing the diaminopurine in the hybridizing oligomer is improved, Finally, a homopurine decamer PNA containing six diaminopurines is shown to form a (gel shift) stable strand displacement complex with a target in a 246 bp double-stranded DNA fragment.