Schumaker V N, Wagnild J
Biophys J. 1965 Nov;5(6):947-64. doi: 10.1016/S0006-3495(65)86761-3.
In this communication is described a new technique for the determination of sedimentation coefficients of macromolecules banded in equilibrium density gradients. Initially, the macromolecules are banded in the analytical ultracentrifuge at a low temperature of about 5 degrees C. After equilibrium has been obtained, the temperature is increased to 25 degrees C. The equilibrium band will now sediment to a new equilibrium position in the ultracentrifuge cell: (a) By following the position of the migrating band as a function of time, sedimentation coefficients may be determined. (b) If several species having different sedimentation coefficients are present in the original band, then during the course of the migration the band may split into several new bands which eventually reunite at the final equilibrium position. (c) If different chemical species of macromolecules such as nucleic acids and carbohydrates are present, in general they will exhibit different temperature density relationships, and can move different distances and directions in response to temperature change.
本文介绍了一种用于测定在平衡密度梯度中形成条带的大分子沉降系数的新技术。首先，在约5℃的低温下，将大分子在分析超速离心机中形成条带。达到平衡后，将温度升至25℃。此时，平衡条带将在超速离心管中沉降至新的平衡位置：(a) 通过跟踪迁移条带的位置随时间的变化，可以测定沉降系数。(b) 如果原始条带中存在几种具有不同沉降系数的物质，那么在迁移过程中，条带可能会分裂成几个新条带，最终在最终平衡位置重新合并。(c) 如果存在不同化学种类的大分子，如核酸和碳水化合物，一般来说它们将表现出不同的温度-密度关系，并且在温度变化时可以移动不同的距离和方向。
