Damaschun G, Müller J J, Bielka H
Acta Biol Med Ger. 1975;34(2):229-39.
A dynamic model for the structure of ribosomes is developed using X-ray small-angle scattering data and electron micrographs of ribosomes and polysomes. The large subunit has the shape of a conical frustum, and has a groove at its flat side. The small subunit consists of two semiparticles which are connected by a molecular strand; it may assume two conformations: a prolate P conformation and an oblate O conformation. Translocation of the ribosome along the mRNA in the elongation process of protein synthesis is accomplished by cyclic conformation transitions P-O-P-O in combination with the linking and rupturing of bonds. This mechanism is called "rack and roll" mechanism.
利用核糖体和多核糖体的X射线小角散射数据及电子显微照片，建立了核糖体结构的动态模型。大亚基呈截头圆锥体形状，在其平面一侧有一条凹槽。小亚基由通过分子链相连的两个半颗粒组成；它可能呈现两种构象：长形的P构象和扁圆形的O构象。在蛋白质合成的延伸过程中，核糖体沿mRNA的移位是通过P - O - P - O的循环构象转变以及键的连接和断裂来完成的。这种机制被称为“齿条与齿轮”机制。
