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The 1H NMR spectrum of a self complementary deoxyhexanucleotide (d-TGGCCA) in water solution has been completely and unambiguously assigned by use of two-dimensional techniques and phosphorus off-resonance decoupling experiments. The helix-coil transition has been monitored by following most of the non-exchangeable protons against temperature and was shown to be a cooperative dissociation-association process. Sequential fraying is sizable even at low temperature. Considerations of coupling constants and of Nuclear Overhauser effects show the helix to be of the B-DNA type.
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