Serdyuk I, Baranov V, Tsalkova T, Gulyamova D, Pavlov M, Spirin A, May R
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region.
Biochimie. 1992 Apr;74(4):299-306. doi: 10.1016/0300-9084(92)90107-p.
We describe three groups of small angle neutron scattering (SANS) experiments with translating ribosomes: 1) regular protonated (normal abundance hydrogen) particles; 2) two isotopic hybrid particles which are reconstituted from one protonated and the other deuterated subunit; 3) four isotypic hybrid particles differing from each other by the extent of protein and RNA deuteration. Using the SANS contrast variation method the radii of gyration of protein and RNA components in both ribosomal subunits as well as the intersubunit distance in the pre- and post-translocation states were determined. The results obtained suggest the following model of the ribosome as a dynamic machine. The ribosome oscillates between two major conformers differing in geometrical dimensions. The 'active' (pulsating) part of the ribosome is the 30S subunit. We believe that the movement of its 'head' relative to the passive 50S subunit is the main mechanical act of translocation. The radius of gyration of the 30S subunit and the intersubunit distance change upon the movement. This is corroborated by neutron scattering data.
我们描述了三组对正在进行翻译的核糖体进行的小角中子散射（SANS）实验：1）正常质子化（正常丰度氢）颗粒；2）由一个质子化亚基和另一个氘化亚基重构的两种同位素杂交颗粒；3）四种同型杂交颗粒，它们在蛋白质和RNA氘化程度上彼此不同。使用SANS对比变化法，测定了两个核糖体亚基中蛋白质和RNA组分的回转半径以及转位前后的亚基间距离。所得结果表明核糖体作为一种动态机器的如下模型。核糖体在几何尺寸不同的两个主要构象体之间振荡。核糖体的“活性”（脉动）部分是30S亚基。我们认为其“头部”相对于被动的50S亚基的运动是转位的主要机械行为。30S亚基的回转半径和亚基间距离在运动时会发生变化。中子散射数据证实了这一点。
