Del Toro Miquel, Bucek Pavel, Aviñó Anna, Jaumot Joaquim, González Carlos, Eritja Ramon, Gargallo Raimundo
Department of Analytical Chemistry, University of Barcelona, Marti i Franques 1-11, E-08028 Barcelona, Spain.
Biochimie. 2009 Jul;91(7):894-902. doi: 10.1016/j.biochi.2009.04.012. Epub 2009 May 3.
The B-cell lymphoma-2 (bcl-2) gene contains a region that has been implicated in the regulation of bcl-2 gene expression. This region can form G-quadruplex structures in solution [J.X. Dai, T.S. Dexheimer, D. Chen, M. Carver, A. Ambrus, R.A. Jones, D.Z. Yang, An intramolecular G-quadruplex structure with mixed parallel/antiparallel G-strands formed in the human BCL-2 promoter region in solution, J. Am. Chem. Soc. 128 (2006) 1096-1098.]. Here, we examined the acid-base and conformational equilibria of this G-quadruplex-forming region (BCL2G), as well as its interaction with both the porphyrin TMPyP4 and with the complementary C-rich strand. We used molecular absorption and circular dichroism techniques, in tandem with multivariate analysis tools. The results revealed the formation of an interaction complex BCL2G:TMPyP4 with a stoichiometry of 1:2 and an equilibrium constant equal to 5.0 (+/-2.3) x 10(13) M(-2). Addition of the complementary C-rich strand to BCL2G induces the predominant formation of the Watson-Crick double-helix with an equilibrium constant equal to 10(7.7) M(-1) (at pH 7.1). Finally, the pH-induced formation of quadruplex structures from the Watson-Crick double-helix is characterized.
B细胞淋巴瘤-2（bcl-2）基因包含一个与bcl-2基因表达调控有关的区域。该区域在溶液中可形成G-四链体结构[J.X.戴，T.S.德克斯海默，D.陈，M.卡弗，A.安布鲁斯，R.A.琼斯，D.Z.杨，溶液中人类BCL-2启动子区域形成的具有混合平行/反平行G链的分子内G-四链体结构，《美国化学会志》128（2006）1096 - 1098]。在此，我们研究了这个G-四链体形成区域（BCL2G）的酸碱和构象平衡，以及它与卟啉TMPyP4和富含C的互补链的相互作用。我们结合多元分析工具使用了分子吸收和圆二色技术。结果表明形成了化学计量比为1:2且平衡常数等于5.0（±2.3）×10¹³ M⁻²的相互作用复合物BCL2G:TMPyP4。向BCL2G添加富含C的互补链会诱导主要形成平衡常数等于10⁷·⁷ M⁻¹（在pH 7.1时）的沃森-克里克双螺旋。最后，对由沃森-克里克双螺旋在pH诱导下形成四链体结构进行了表征。
