PDF(Pubmed)
Abstract：
D2 is a structural and cooperative domain of Thermotoga maritima Arginine Binding Protein, that possesses a remarkable conformational stability, with a denaturation temperature of 102.6°C, at pH 7.4. The addition of potassium thiocyanate causes a significant decrease in the D2 denaturation temperature. The interactions of thiocyanate ions with D2 have been studied by means of isothermal titration calorimetry measurements and molecular dynamics simulations. It emerged that: (a) 20-30 thiocyanate ions interact with the D2 surface and are present in its first solvation shell; (b) each of them makes several contacts with protein groups, both polar and nonpolar ones. The addition of guanidinium thiocyanate causes a marked destabilization of the D2 native state, because both the ions are denaturing agents. However, on adding to the solution containing D2 and guanidinium thiocyanate a stabilizing agent, such as TMAO, sucrose or sodium sulfate, a significant increase in denaturation temperature occurs. The present results confirm that counteraction is a general phenomenon for globular proteins.
摘要：
D2是Thermotogamaritima精氨酸结合蛋白的结构和协作域，具有显著的构象稳定性，变性温度为102.6°C，在pH7.4。硫氰酸钾的添加导致D2变性温度的显著降低。通过等温滴定量热法测量和分子动力学模拟研究了硫氰酸根离子与D2的相互作用。结果发现：（a）20-30个硫氰酸根离子与D2表面相互作用，并存在于其第一个溶剂化壳中；（b）它们各自与蛋白质基团进行几次接触，极性和非极性。添加硫氰酸胍会导致D2天然状态明显不稳定，因为这两种离子都是变性剂.然而,在含有D2和硫氰酸胍的溶液中加入稳定剂，比如TMAO,蔗糖或硫酸钠，变性温度显著升高。本结果证实反作用是球状蛋白质的普遍现象。
