THREE-DIMENSIONAL STRUCTURES OF BIOLOGICAL MACROMOLECULES

研究了NK-2类同源结构域的野生型和突变体与罕见的18碱基对dna一致片段的三维结构。此外，还对野生型和选择突变体的动态行为进行了表征。突变时同位结构域的结构变化伴随着分子运动特性的相应变化。人们还观察到野生型模拟物的低频运动，这表明热展开。这些结果表明，热展开的开始伴随着折叠态和未展开态之间的低频交换。对同一野生型和突变型同源结构域的热力学测量已经完成。详细分析了热容随温度的变化，以及DNA结合的焓和熵。结果表明，热展开过程的起始是低频交换运动。一项对人类NK-2同源结构域NKX-2.5成员的详细调查已经启动。研究包括确定全长蛋白（331个残基）的三维结构，以及同源结构域的野生型和突变类似物。同位结构域内的突变与几种形式的先天性心脏病直接相关。我们已经证明，这些与疾病相关的突变都导致同源结构域或其DNA结合行为的显著结构改变。

The three-dimensional structure of the wild type and mutants of homeodomains in the NK-2 class bound to an uncommon 18 base-pairDNA consensus segment have been studied. In addition, the dynamic behavior of the wild type and selected mutants have been characterized. Structural changes in the homeodomain upon mutation are accompanied by corresponding changes in the motional properties of the molecule. One also observes low frequency motions in the wild type analog that are indicative of thermal unfolding. These results imply that the initiation of thermal unfolding is accompanied by low frequency exchange between the folded and unfolded states. Thermodynamic measurements on the same wild type and mutant homeodomains has been completed. The change in the heat capacity with temperature, as well as the enthalpies and entropies of DNA binding were analyzed in detail. The results imply that the initiation of the thermal unfolding process involves low frequency exchange motion.A detailed investigation of a human member of the NK-2 class of homeodomains, NKX-2.5 has been initiated. Studies include a determination of the three-dimensional structure of the full length protein (331 residues) as well as the wild type and mutant analogs of the homeodomain. Mutations within the homeodomain are directly associated with several forms of congenital heart disease. We have shown that these mutations associated with disease all result in either significant structural alterations of the homeodomain or in its DNA binding behavior.