Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Biochemistry. 2011 Aug 23;50(33):7077-9. doi: 10.1021/bi200750k. Epub 2011 Jul 26.
Lymphotactin (Ltn) is a unique chemokine that under physiological solution conditions displays large-scale structural heterogeneity, defining a new category of "metamorphic proteins". Previous Ltn studies have indicated that each form is required for proper function, but the mechanism of interconversion remains unknown. Here we have investigated the temperature dependence of kinetic rates associated with interconversion and unfolding by stopped-flow fluorescence to determine transition-state free energies. Comparisons of derived thermodynamic parameters revealed striking similarities between interconversion and protein unfolding. We conclude that Ltn native-state rearrangement proceeds by way of a large-scale unfolding process rather than a unique intermediate structure.
淋巴细胞趋化因子 (Ltn) 是一种独特的趋化因子，在生理溶液条件下显示出大规模的结构异质性，定义了一个新的“变形蛋白”类别。先前的 Ltn 研究表明，每种形式都是正常功能所必需的，但转换机制仍然未知。在这里，我们通过停流荧光法研究了与转换和展开相关的动力学速率对温度的依赖性，以确定过渡态自由能。衍生热力学参数的比较表明，转换和蛋白质展开之间存在惊人的相似性。我们的结论是，Ltn 天然状态的重排是通过大规模展开过程而不是独特的中间结构进行的。
