Thumm W, Seidl A, Hinz H J
Institut für Biophysik und Physikalische Biochemie, Universität Regensburg, FRG.
Nucleic Acids Res. 1988 Dec 23;16(24):11737-57. doi: 10.1093/nar/16.24.11737.
Differential scanning microcalorimetry (DSC), UV absorption and circular dichroism (CD) have been used to study structure and stability of linear (lin), open circular (oc), supercoiled (cd) and relaxed circular duplex (rd) DNA and calf thymus (CT) DNA. Investigations were made in low salt buffer and in the presence of 7.2 M NaClO4. The chaotropic action of perchlorate promotes a reduction of the overall stability of DNA, which permits a direct determination of the transition enthalpies of all four DNA configurations. The stabilities against thermal denaturation have been found to increase in the series lin approximately oc less than cd less than rd. These relative stabilities can be rationalized on the basis of the linkage between supercoiling and secondary structural changes in topologically constrained duplex DNA. On the basis of these studies, a model of the melting process could be suggested that is consistent with the energetic and spectroscopic data.
差示扫描量热法（DSC）、紫外吸收和圆二色性（CD）已被用于研究线性（lin）、开环（oc）、超螺旋（cd）和松弛环状双链（rd）DNA以及小牛胸腺（CT）DNA的结构和稳定性。研究是在低盐缓冲液中以及7.2 M高氯酸钠存在的情况下进行的。高氯酸盐的离液序列高的作用促进了DNA整体稳定性的降低，这使得能够直接测定所有四种DNA构型的转变焓。已发现抗热变性的稳定性在lin约oc小于cd小于rd的序列中增加。这些相对稳定性可以基于超螺旋与拓扑受限双链DNA二级结构变化之间的联系来进行合理解释。基于这些研究，可以提出一个与能量和光谱数据一致的熔解过程模型。
