Kebbekus P, Draper D E, Hagerman P
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Biochemistry. 1995 Apr 4;34(13):4354-7. doi: 10.1021/bi00013a026.
A set of 10 double-stranded RNAs ranging in length from 92 to 317 base pairs has been synthesized, and their rotational diffusion times were measured by transient electric birefringence. A hydrodynamic analysis of the birefringence decay data yields a helix persistence length of 720 +/- 70 A, based on a helix with an effective hydrodynamic diameter of 26 A and a rise per base pair of 2.7 A in the presence of Mg2+ ions. Thus, duplex RNA is somewhat stiffer than DNA, for which the persistence length is 450-500 A. The measurements also suggest that (i) current hydrodynamic theory for the rotational decay times is applicable to RNA molecules that are longer than 100 base pairs and (ii) weak Mg(2+)-RNA association decreases the rise per base pair slightly, by no more than 0.1 A.
已合成了一组10条双链RNA，长度从92至317个碱基对不等，并通过瞬态电双折射测量了它们的旋转扩散时间。基于在Mg2+离子存在下有效流体动力学直径为26 Å且每碱基对上升2.7 Å的螺旋结构，对双折射衰减数据进行的流体动力学分析得出螺旋持续长度为720±70 Å。因此，双链RNA比DNA稍微更硬一些，DNA的持续长度为450 - 500 Å。这些测量结果还表明：(i) 当前关于旋转衰减时间的流体动力学理论适用于长度超过100个碱基对的RNA分子；(ii) 弱的Mg(2+)-RNA缔合使每碱基对的上升略有减少，不超过0.1 Å。
