NMR Structural Studies on a Nonnatural Deoxyribonucleoside Mediated Recognitionof GC Base Pairs in Pyrimidine-Purine-Pyrimidine Triplexes

摘要

As a part of our ongoing efforts to define the structural aspects of unusualpairing alignments in DNA triplexes by Nuclear Magnetic Resonance spectroscopy, we have examined the structural role of a nonnatural deoxyribonucleoside, P1, that has been shown to mediate the recognition of GC base pairs in pyrimidine-purine-pyrimidine DNA triplexes. A qualitative interpretation of the NMR data indicates that this analog of protonated cytosines is readily accommodated in the third strand segment of an intramolecular triplex system. Furthermore, the observed NOE patterns position the imino and amino protons of P1 opposite the Nitrate and Oxide atome of guanine respectively, consistent with the previously proposed pairing scheme.