由d(TGGGTGGGTGGTTGGGTGGG)与位于小鼠Ki-ras原癌基因启动子中的关键R.Y序列形成的DNA三链体的表征。

Characterization of the DNA triplex formed by d(TGGGTGGGTGGTTGGGTGGG) and a critical R.Y sequence located in the promoter of the murine Ki-ras proto-oncogene.

作者信息

Xodo L E

机构信息

Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Italy.

出版信息

FEBS Lett. 1995 Aug 14;370(1-2):153-7. doi: 10.1016/0014-5793(95)00829-x.

DOI:10.1016/0014-5793(95)00829-x

PMID:7649296

Abstract

The binding of the G-rich oligonucleotide d(TGGGTGGGTGGTTGGGTGGG) to a critical homopurine-homopyrimidine sequence located in the promoter of the murine Ki-ras proto-oncogene has been investigated. The duplex and the oligonucleotide form a triple helix as evidenced by band-shift electrophoresis, hydroxyapatite (HA) chromatography, UV-melting and circular dichroism (CD) experiments. Upon thermal denaturation in 50 mM Tris-acetate, pH 7.4, 50 mM NaCl, 10 mM MgCl2, 0.1 mM spermine the triplex exhibits two cooperative transitions: one of these is attributed to the triplex-to-duplex transformation, the other to the duplex-to-coil transformation. The thermodynamic parameters of triplex formation have been determined by a van't Hoff analysis of the UV-melting curves which provided values of delta H = 79 +/- 8 kcal/mol, delta S = 224 +/- 22 e.u., delta G298 = 12.2 +/- 1.2 kcal/mol. These data are compared with those reported for the YRY triplex motif.

摘要

已对富含G的寡核苷酸d(TGGGTGGGTGGTTGGGTGGG)与位于小鼠Ki-ras原癌基因启动子中的关键同型嘌呤-同型嘧啶序列的结合进行了研究。通过凝胶迁移电泳、羟基磷灰石（HA）色谱、紫外熔解和圆二色性（CD）实验证明，双链体和该寡核苷酸形成了三链螺旋。在50 mM Tris-乙酸盐（pH 7.4）、50 mM NaCl、10 mM MgCl2、0.1 mM精胺中进行热变性时，三链体呈现出两个协同转变：其中一个归因于三链体向双链体的转变，另一个归因于双链体向单链卷曲的转变。通过对紫外熔解曲线进行范特霍夫分析确定了三链体形成的热力学参数，结果为ΔH = 79 ± 8 kcal/mol，ΔS = 224 ± 22 e.u.，ΔG298 = 12.2 ± 1.2 kcal/mol。将这些数据与报道的YRY三链体基序的数据进行了比较。