| Summary: | 碩士 === 國立臺灣師範大學 === 化學學系 === 85 ===
We are utilized solid-state deuterium NMR spectroscopy to reveal the dynamical nature of DNA structure.Two model system were in used .The first triplex model system, namely d(A)6 .d(T)6, which consists of d(AAAAAA) & d(TTTTTT).The other triplex model system, namely d(AG)3.d(CC), which consists of d(AGAGAG) & a - folded d(TCTCTCTTTTCTCTCT).This model system allow us to only single-stranded & triplet-stranded DNA.For both triplex model compounds, all purine CH8 of the central strand were exchanged by deuteron.
At all levels of hydration, the data reveal the presence of a rapid, small-amplitude liberation of the base (τc ……≦1ns, 3o~10oamplitude).At the higher hydration levels(82% relative humidity or higher), the results indicate the presence of a much slow motion (τc~10-100μs).The 2H NMR results were analyzed with a dynamical model which treats the oligonucleotide as a deformable filament & which can include collective torsional fluctuation.The slow motion observed at high hydration levels is attributed to the uniform twisting model.
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