等温滴定量热法
焓
熵(时间箭头)
热力学
DNA
吉布斯自由能
人口
化学
转录因子
物理
基因
生物化学
社会学
人口学
作者
Ekaterina Morgunova,Yimeng Yin,Pratyush Kumar Das,Arttu Jolma,Fei Zhu,A. Popov,You Xu,Lennart Nilsson,Jussi Taipale
出处
期刊:eLife
[eLife Sciences Publications, Ltd.]
日期:2018-04-11
卷期号:7
被引量:33
摘要
Most transcription factors (TFs) can bind to a population of sequences closely related to a single optimal site. However, some TFs can bind to two distinct sequences that represent two local optima in the Gibbs free energy of binding (ΔG). To determine the molecular mechanism behind this effect, we solved the structures of human HOXB13 and CDX2 bound to their two optimal DNA sequences, CAATAAA and TCGTAAA. Thermodynamic analyses by isothermal titration calorimetry revealed that both sites were bound with similar ΔG. However, the interaction with the CAA sequence was driven by change in enthalpy (ΔH), whereas the TCG site was bound with similar affinity due to smaller loss of entropy (ΔS). This thermodynamic mechanism that leads to at least two local optima likely affects many macromolecular interactions, as ΔG depends on two partially independent variables ΔH and ΔS according to the central equation of thermodynamics, ΔG = ΔH - TΔS.
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