适体
G-四倍体
鸟嘌呤
化学
序列(生物学)
化学稳定性
差示扫描量热法
变性(裂变材料)
理论(学习稳定性)
DNA
结晶学
核酸变性
生物物理学
热力学
基序列
核苷酸
物理
生物化学
生物
分子生物学
有机化学
机器学习
核化学
基因
计算机科学
作者
Иван Смирнов,Richard H. Shafer
出处
期刊:Biochemistry
[American Chemical Society]
日期:2000-01-20
卷期号:39 (6): 1462-1468
被引量:260
摘要
The thrombin aptamer is a 15-mer oligodeoxyribonucleotide that folds into a unimolecular quadruplex consisting of a stack of two guanine quartets connected by two external loops and one central loop and possesses a high affinity for thrombin. We have undertaken a systematic examination, in KCl, of the thermodynamic stability of thrombin aptamer analogues containing sequence modifications in one or more of the loops, as well as in the number of quartets. UV melting studies have been carried out to obtain the relevant thermodynamic parameters for these aptamers. van't Hoff analysis of these data, with a two-state model for unimolecular denaturation, gave excellent fits to the experimental observations. Thermodynamic analysis indicates that the central loop sequence in the parent aptamer is optimal for stability. Modifications in this or other loops can effect either DeltaH degrees, DeltaS degrees, or both. Addition of a single G at the 5'-end decreases stability while addition of a G at the 3'-end increases stability. Differential scanning calorimetry experiments on the thrombin aptamer reveal that a heat capacity change, not detected by UV measurements, accompanies the unfolding of the aptamer.
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