SynopsisWe report the assignment of the backbone 'H-and 31P-nmr lines in the synthetic hexadeoxyribonucleotide pentaphosphate duplex d(GCATGC),, using double quantum filtered 'H-lH correlation spectroscopy, 'H observed IH3P heteronuclear correlation spectroscopy, and 31P relayed 'H-IH correlation spectroscopy. The strategy used enables one to make sequence-specific resonance assignments without reference to a known or assumed conformation of the DNA fragment.