Ortega A, García de la Torre J
Departamento de Química Física, Facultad de Química, Universidad de Murcia, 30071 Murcia, Spain.
Biomacromolecules. 2007 Aug;8(8):2464-75. doi: 10.1021/bm700473f. Epub 2007 Jul 24.
The equivalent radius for any solution property is the radius of a spherical particle having the same value of solution property as that of the macromolecule under consideration. Equivalent radii for different properties present a dependence on size and shape that are more similar than the values of the properties themselves. Furthermore, the ratios of equivalent radii of two properties depend on the conformation (shape or flexibility), but not on the absolute sizes. We define equivalent radii and their ratios, and describe their evaluation for some common models of rigid and flexible macromolecules. Using radii and ratios, we have devised procedures to fit macromolecular models to experimental properties, allowing the determination of the model parameters. Using these quantities, we can construct target functions for an equilibrated, unbiased optimization. The procedures, which have been implemented in public-domain computer programs, are illustrated for rigid, globular proteins, and the rodlike tobacco mosaic virus, and for semiflexible, wormlike heparin molecules.
任何溶液性质的等效半径是指具有与所考虑的大分子相同溶液性质值的球形颗粒的半径。不同性质的等效半径呈现出对尺寸和形状的依赖性，这种依赖性比性质本身的值更为相似。此外，两种性质的等效半径之比取决于构象（形状或柔韧性），而不取决于绝对尺寸。我们定义了等效半径及其比率，并描述了它们对于一些刚性和柔性大分子常见模型的评估方法。利用半径和比率，我们设计了将大分子模型拟合到实验性质的程序，从而能够确定模型参数。使用这些量，我们可以构建用于平衡、无偏优化的目标函数。这些程序已在公共领域的计算机程序中实现，文中针对刚性球状蛋白质、杆状烟草花叶病毒以及半柔性蠕虫状肝素分子进行了说明。
