Li S J, Marshall A G
Biochemistry. 1985 Jul 16;24(15):4047-52. doi: 10.1021/bi00336a037.
Unfolding of purified wheat germ ribosomal RNA has been studied by differential scanning calorimetry (DSC) from 15 to 95 degrees C, in the presence and absence of 100 mM NaCl and/or 10 mM MgCl2. The total enthalpy of melting varies from about 290 (no sodium or magnesium) to 480 kcal/mol (Mg2+ only) and precisely accounts for the number and types of base pairs deduced from prior Fourier-transform infrared experiments. The composite DSC curves are analyzed into four individual two-state melting stages. Both Na+ and Mg2+ shift the melting transitions to higher temperature; in addition, Mg2+ causes the individual transitions to merge (i.e., melt cooperatively) and leads to irreversible chain cleavage at high temperature. The results are analyzed according to three general secondary base-pairing models for eukaryotic 5S RNA.
利用差示扫描量热法（DSC），在15至95摄氏度的温度范围内，研究了纯化的小麦胚芽核糖体RNA在有和没有100 mM氯化钠和/或10 mM氯化镁存在的情况下的解折叠情况。熔解的总焓从约290千卡/摩尔（无钠或镁）变化到480千卡/摩尔（仅镁离子），并且精确地与先前傅里叶变换红外实验推断出的碱基对的数量和类型相符。复合DSC曲线被分析为四个单独的两态熔解阶段。钠离子和镁离子都将熔解转变移向更高温度；此外，镁离子导致各个转变合并（即协同熔解），并在高温下导致不可逆的链断裂。根据真核生物5S RNA的三种一般二级碱基配对模型对结果进行了分析。
