Zhu Huihe, Lewis Frederick D
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Bioconjug Chem. 2007 Jul-Aug;18(4):1213-7. doi: 10.1021/bc060279u. Epub 2007 May 4.
The formation and properties of G-quadruplex structures from short single-strand oligonucleotide conjugates possessing two to four guanines and a 5'-terminal pyrenebutanol are reported. The 4-G conjugate forms a stable G-quadruplex under low or high potassium ion concentrations, whereas the 3-G conjugate forms a stable G-quadruplex only in the presence of high potassium. The 2-G conjugate fails to form a stable G-quadruplex even at low temperature and high potassium concentration. Both pyrene monomer and excimer fluorescence are observed for the G-quadruplex structures, whereas only monomer fluorescence is observed for the single-strand conjugates. Thus, pyrene excimer fluorescence can be used as a probe for the formation of G-quadruplex structures. The excimer/monomer intensity ratios for the G-quadruplex structures are dependent upon both the temperature and potassium or lithium salt concentration. The salt effect is attributed to a change in the structure of the hydrophobic pyrene chromophores, which are assembled on the 5'-face of the G-quadruplex as a consequence of electrostriction.
报道了具有两到四个鸟嘌呤和一个5'-末端芘丁醇的短单链寡核苷酸缀合物形成G-四链体结构及其性质。4-G缀合物在低钾或高钾离子浓度下形成稳定的G-四链体，而3-G缀合物仅在高钾存在下形成稳定的G-四链体。2-G缀合物即使在低温和高钾浓度下也不能形成稳定的G-四链体。对于G-四链体结构，芘单体荧光和激基缔合物荧光均能被观察到，而对于单链缀合物则仅能观察到单体荧光。因此，芘激基缔合物荧光可作为G-四链体结构形成的探针。G-四链体结构的激基缔合物/单体强度比取决于温度以及钾盐或锂盐浓度。盐效应归因于疏水性芘发色团结构的变化，这些发色团由于电致伸缩作用而聚集在G-四链体的5'-面上。
