Díaz F G, Iniesta A, García de la Torre J
Departamento de Química Física, Facultad de Ciencias Químicas y Matemáticas, Universidad de Murcia, Spain.
Biopolymers. 1990;30(5-6):547-54. doi: 10.1002/bip.360300507.
A simple bead model is proposed for the antibody molecule immunoglobulin IgG1. The partial flexibility of the hinge is represented by a quadratic potential associated to the angles between arms. Conformational and hydrodynamic properties are calculated using Monte Carlo (rigid-body) and Brownian dynamics simulations. Comparison of experimental and calculated values for some overall properties allows the assignment of dimensions and other model parameters. The Brownian dynamics technique is used next to simulate a rotational correlation function that is comparable with the decay of fluorescence emission anisotropy. This is done with varying flexibility at the hinge. The longest relaxation time shows a threefold decrease when going from the rigid Y-shaped conformation to the completely flexible case. The calculations are in good agreement with the decay times observed for IgG1. A flexibility analysis of the latter indicates that a variability of +/- 55 degrees (standard deviation) in the angle between the Fab arms.
提出了一种针对抗体分子免疫球蛋白IgG1的简单珠子模型。铰链的部分柔韧性由与臂间角度相关的二次势表示。使用蒙特卡罗（刚体）和布朗动力学模拟计算构象和流体动力学性质。通过比较一些整体性质的实验值和计算值来确定尺寸和其他模型参数。接下来使用布朗动力学技术模拟与荧光发射各向异性衰减可比的旋转相关函数。这是在铰链处具有不同柔韧性的情况下完成的。当从刚性Y形构象转变为完全柔性的情况时，最长弛豫时间减少了三倍。计算结果与IgG1观察到的衰减时间非常吻合。对后者的柔韧性分析表明，Fab臂间角度的变化范围为±55度（标准差）。
