| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 84 === We are utilized solid-state deuterium NMR spectroscopy to
reveal the dynamic nature of DNA structure. Two model system
were investigated. The first triplex model system, namely d(GA)4
.2d(TC)4, which consists of d(GAGAGAGA) and d(TCTCTCTC). This
model system permit us to study single-stranded, double-stranded
as well as triple-stranded DNA in sequence. Whereas, the other
triplex model system, namely d(AG)3.d(CC), which consists of d(
AGAGAG) and a folded d(TCTCTCTTTTCTCTCT). This model system
allow us to study only single-stranded and triple-stranded DNA.
For both triplex model compounds, all purine C8H of the central
strand were exchanged by deuteron. We have some interesting
conclusion: a. In dry DNA, The spin-lattice relaxation time(T1)
was much smaller than dry Adenine and Guanine and didn't affect
by single-stranded﹑double-stranded and triple-stranded
conformations. b. At 80% humidity, T1 and T2e decreased greatly,
and the central position of the spectroscopy was lower than 0%.
This may be caused by the rotation or bending about helix axis.
c. At 98% humidity, the T2e of single-stranded and double-
stranded DNA were higher than 80% and 90% humidity, this implied
that the motion observed at 80% humidity was speeded up from μ
sec to nsec when the humidity increased. We assumed this motion
must be global motion. d. T2e of triple-stranded DNA
increasedabove 90% humidity, indicated that the global motion
was affected easily by structure.
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