Goss D J, Parkhurst L J, Mehta A M, Wahba A J
Nucleic Acids Res. 1983 Aug 25;11(16):5589-602. doi: 10.1093/nar/11.16.5589.
We have determined the equilibrium constants for the binding of AEDANS-labelled S1 to S1-depleted 30S and 70S ribosomes. For "tight" ribosomes, the association of S1 increases with the sixth power of Mg2+ concentration, but for 30S subunits and "loose" ribosomes, there is virtually no dependence of the association on Mg2+ over the same concentration range, 2-10 mM in Mg2+. The binding of S1 to 70S ribosomes at 10 mM Mg2+ is stabilized by 2 kcal/mol compared to the binding to 30S subunits. When intact S1 binds to tight ribosomes, the fluorescence anisotrophy is that for virtually complete rotational immobilization. The anisotropies vary considerably with the preparation and treatment of both S1 and ribosomes and these variations are detailed here. The results suggest the linkage of Mg2+-dependent conformational changes in the intact ribosomes, perhaps including rRNA, and the binding of S1.
我们已经测定了AEDANS标记的S1与去除S1的30S和70S核糖体结合的平衡常数。对于“紧密”核糖体,S1的结合随着Mg2+浓度的六次方增加,但对于30S亚基和“松散”核糖体,在相同的2 - 10 mM Mg2+浓度范围内,结合几乎不依赖于Mg2+。与结合到30S亚基相比,在10 mM Mg2+条件下S1与70S核糖体的结合稳定了2千卡/摩尔。当完整的S1与紧密核糖体结合时,荧光各向异性表明几乎完全旋转固定。各向异性随S1和核糖体的制备及处理有很大变化,这里详细介绍了这些变化。结果表明完整核糖体中Mg2+依赖性构象变化(可能包括rRNA)与S1结合之间存在联系。