El-Sayed Ahmed A, Pedersen Erik B, Khaireldin Nahid A
Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark.
Nucleosides Nucleotides Nucleic Acids. 2012;31(12):872-9. doi: 10.1080/15257770.2012.742199.
Certain cytosine-rich (C-rich) DNA sequences can fold into secondary structures as four-stranded i-motifs with hemiprotonated base pairs. Here we synthesized C-rich TINA-intercalating oligonucleotides by inserting a nonnucleotide pyrene moiety between two C-rich regions. The stability of their i-motif structures was studied by using UV melting temperature measurements and circular dichroism spectra at different pH values under noncrowding and crowding conditions (20% poly(ethylene glycol)). When TINA ((R)-3-((4-(1-pyrenylethynyl)benzyl)oxy) propane-1,2-diol) is inserted, the oligonucleotides could form an i-motif at a higher pH than observed for the corresponding wildtype oligonucleotide.
某些富含胞嘧啶（C-rich）的DNA序列可以折叠成具有半质子化碱基对的四链体i-基序二级结构。在这里，我们通过在两个富含C的区域之间插入一个非核苷酸芘部分，合成了富含C的TINA嵌入寡核苷酸。在非拥挤和拥挤条件（20%聚乙二醇）下，通过紫外熔解温度测量和不同pH值下的圆二色光谱研究了它们的i-基序结构的稳定性。当插入TINA（（R）-3-（（4-（1-芘乙炔基）苄基）氧基）丙烷-1,2-二醇）时，寡核苷酸可以在比相应野生型寡核苷酸更高的pH值下形成i-基序。
