Tran-Dinh S, Neumann J M, Huynh-Dinh T, Simmonot G, Igolen J
C R Seances Acad Sci III. 1982 Jan 4;294(1):5-8.
The helix-coil transition of dACATGT was investigated by 1H-NMR spectroscopy at 276 and 400 MHz. The results suggest that the fraying process only consists of two stages: The AT extreme base pairs open at first then the GC internal and AT central base pairs open simultaneously at higher temperatures. The midpoint temperature of each base pair, the helix-coil dissociation constants and the corresponding enthalpy were determined from the delta = f (t degree) curves of non exchangeable protons. The unusual line width of the H1, proton resonance of the cytidine residue, observed at t less than 42 degree C was attributed to the fact that this proton is located in the proximity of the (cytoxine) C = O ... H2N (guanine) hydrogen bond.
通过在276兆赫和400兆赫下的1H-NMR光谱研究了dACATGT的螺旋-卷曲转变。结果表明，解链过程仅包括两个阶段：首先是AT末端碱基对打开，然后在较高温度下GC内部碱基对和AT中心碱基对同时打开。从不可交换质子的δ=f（t℃）曲线确定了每个碱基对的中点温度、螺旋-卷曲解离常数和相应的焓。在t小于42℃时观察到的胞嘧啶残基H1质子共振的异常线宽归因于该质子位于（胞嘧啶）C=O...H2N（鸟嘌呤）氢键附近这一事实。
