15N-Labeled Oligodeoxynucleotides -Useful Probes for1H-NMR Investigations

The amino protons of 15N-labeled deoxyoligonucleotides were studied as possible structural probes for NMR investigations of the interaction between DNA and regulatory proteins. To apply this strategy, 6-15NH2-2′ -deoxyadenoslne, 4-15NH -2′-deoxycytidine and 2-15NH -2′-deoxyguanosine were chemically synthesized. The labeled nucleosides were introduced into distinct positions of oligodeoxy-nucleotides by large-scale DNA synthesis. The behaviour of the 15N-coupled cytidine amino protons in a 18 base pair (bp) lac operator sequence were investigated using H-15N INDOR spectroscopy .