T.C.G triplet in an antiparallel purine.purine.pyrimidine DNA triplex. Conformational studies by NMR

The antiparallel purine-purine-pyrimidine DNA triplex, RRY6, which contains a T-C-G inverted triplet in the center of the sequence, was examined by proton and phosphorous two-dimensional NMR spectroscopy. The local conformation of the T.C.G triplet (T4.C11.G18) and the effect of this triplet on the global helical structure were analyzed in detail. The formation of the T.C.G triplet is confirmed by a set of cross-strand NOEs, including unusual cross-strand NOEs between the third strand and the pyrimidine strand as opposed to the purine strand of the duplex