G-四链体序列的微小变化对结构及钾离子传感的影响

Influence of small changes in G-quadruplex sequence on structure and potassium ion detection

人体端粒DNA重复单元GGGTTA在K^＋溶液中可以形成G-四链体结构,并已成功利用结构变化过程中的荧光改变进行K＋的检测。在此基础上研究了在寡聚核苷酸的GGG部分插入腺嘌呤碱基A对G-四链体结构及在K＋检测中的影响。借助圆二色光谱、质谱和荧光光谱的方法可以分别获得序列变化引起的G1四链体排列的平行或反平行结构,可以结合的K＋数目,以及在K^＋传感时所适用的K＋浓度范围。在GGG中插入A可以使K^＋更容易进入G-四链体分子空穴,但当在两个GGG中同时插入A时,G-四链体结构难以形成。基于K＋线性响应范围的变化（由0.02-1 mmol/L变为0.2-16 mmol/L）,可以改进基于DNA的K＋传感器,使直接测定人体血清中K＋的含量成为可能。

Human telomeric DNA repeat sequence GGGTYA can form G-quadruplex structure in the presence of potassium ions, and has been successfully used in the detection of potassium ions based on fluorescence change in the process of structure change. This paper studies the influence of inserting adenine bases A in the oligonueleotide GGG section on structure and potassium ion detection. We can obtain the parallel or antiparallel structure of G-quadruplex caused by sequence changes, the number of potassium ions occupied and the potassium ion concentration range using circular diehroism, mass spectrometry and fluorescence spectroscopy, respectively. Results indicate that potassium ions are easier to enter G-quadruplex as inserting adenine base A in the GGG, whereas G-quadruplex is difficult to form as inserting A in two GGG at the same time. We can improve the response range of potassium ion sensors from 0. 02 - 1 mmol/L to 0. 2 - 16 mmol/L which can directly determine the potassium ion content in human serum.