Middaugh C R, Steadman B L, Schurtenberger P, Lee D C, Chlebowski J F
Merck Research Laboratories, West Point, PA 19486.
Biochim Biophys Acta. 1993 Feb 13;1161(2-3):328-32. doi: 10.1016/0167-4838(93)90233-h.
Employing a combination of static and dynamic light scattering, as well as differential scanning calorimetry (DSC), the structural changes which appear in alpha 2-macroglobulin (alpha 2M) upon trypsin binding have been further characterized. Light-scattering measurements suggest that a 15% reduction in both the hydrodynamic radius and radius of gyration occurs when two molecules of trypsin complex to alpha 2M. Approx. 85% of this trypsin-induced compaction results from the binding of the first proteinase. A complementary result was obtained from DSC measurements in which the major fraction of the trypsin-induced conversion of alpha 2M to a single more thermally stable form results from interaction with the first proteinase molecule. These observations support a functionally asymmetric model of trypsin binding to alpha 2M in which the significant reduction in size of the complex is primarily due to the initial interaction of alpha 2M with a single proteinase molecule.
通过结合静态和动态光散射以及差示扫描量热法（DSC），进一步表征了α2-巨球蛋白（α2M）与胰蛋白酶结合后出现的结构变化。光散射测量表明，当两个胰蛋白酶分子与α2M形成复合物时，流体动力学半径和回转半径均减小15%。这种由胰蛋白酶诱导的压缩约85%是由第一个蛋白酶的结合引起的。从DSC测量中获得了一个互补的结果，其中α2M向单一热稳定性更高的形式的胰蛋白酶诱导转化的主要部分是由与第一个蛋白酶分子的相互作用引起的。这些观察结果支持了胰蛋白酶与α2M结合的功能不对称模型，其中复合物大小的显著减小主要是由于α2M与单个蛋白酶分子的初始相互作用。
