Hydration changes in the association of Hoechst 33258 with DNA
Hydration changes in the association of Hoechst 33258 with DNA
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DOI：
10.1021/bi051769x
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发表时间：
2005-12-27
期刊：
影响因子：
2.9
通讯作者：
Petty, JT
中科院分区：
文献类型：
--
作者：
Kiser, JR;Monk, RW;Petty, JT
用量热法和平衡常数法研究了水在Hoechst 33258与(Aatt)(2)序列的小凹槽结合位相互作用中的作用。用等温滴定量热法测得该反应的热容变化为-256+/-10卡/(Hoechst的Kmo1)。与基于面积模型的热容变化相比，支持水从Hoechst-DNA复合体的界面排出。为了进一步考虑水的作用，渗透胁迫方法被用来确定Hoechst与DNA的关联是否伴随着水合作用的变化。使用四种不同分子量和化学性质的渗透分子，随着渗透分子浓度的增加，Hoechst对DNA的亲和力降低。根据平衡常数对溶液渗透压的依赖关系，络合物中相对于反应物获得了60+/-13水。提出渗透应力技术是测量弱结合水，而不是通过热容变化来测量的。
The role of water in the interaction of Hoechst 33258 with the minor groove binding site of the (AATT)(2) sequence was investigated using calorimetric and equilibrium constant measurements. Using isothermal titration calorimetry measurements, the heat capacity change for the reaction is -256 +/- 10 cal/(K mol of Hoechst). Comparison with the heat capacity changes based on area models supports the expulsion of water from the interface of the Hoechst-DNA complex. To further consider the role of water, the osmotic stress method was used to determine if the Hoechst association with DNA was coupled with hydration changes. Using four osmolytes with varying molecular weights and chemical properties, the Hoechst affinity for DNA decreases with increasing osmolyte concentration. From the dependence of the equilibrium constant on the solution osmolality, 60 +/- 13 waters are acquired in the complex relative to the reactants. It is proposed that the osmotic stress technique is measuring weakly bound waters that are not measured via the heat capacity changes.