DNA中A到B构象转变的振动圆二色性研究。

Vibrational circular dichroism studies of the A-to-B conformational transition in DNA.

作者信息

Wang L, Keiderling T A

机构信息

Department of Chemistry, University of Illinois, Chicago 60680.

出版信息

Biochemistry. 1992 Oct 27;31(42):10265-71. doi: 10.1021/bi00157a013.

DOI:10.1021/bi00157a013

PMID:1420146

Abstract

The vibrational circular dichroism (VCD) spectra of several natural DNAs as well as tRNA, poly(dG-dC).poly(dG-dC), and poly(dA-dT).poly(dA-dT) are reported for the base deformation modes in the IR region from 1700 to 1550 cm-1 for the polymers in D2O as well as in high alcohol dehydrating conditions. Spectra of both the B- and A-forms were identified. The A-form DNA VCD, not previously reported, has characteristics that can be found in the VCD spectra of RNAs as would be expected from the similarity of their structures. The VCD is sequence-dependent. Under the dehydrating conditions studied, poly(dA-dT)poly(dA-dT),poly(dA).poly(dT), and a high-A-T fraction natural DNA had a different bandshape from the other DNAs, which was similar to that of poly(rA).poly(rU). Poly(dG-dC).poly-(dG-dC) did not form an A-form in high-alcohol conditions but instead had a VCD spectrum much like that of its high-salt-induced Z-form. Qualitative differences seen experimentally between A- and B-form DNA VCD were suggested by the differences in the coupled oscillator VCD calculated for the two forms.

摘要

报道了几种天然DNA以及tRNA、聚（dG-dC）·聚（dG-dC）和聚（dA-dT）·聚（dA-dT）在重水（D₂O）中以及在高醇脱水条件下聚合物在1700至1550 cm⁻¹红外区域的碱基变形模式的振动圆二色性（VCD）光谱。鉴定出了B型和A型的光谱。此前未报道过的A型DNA的VCD具有在RNA的VCD光谱中可以发现的特征，这正如从它们结构的相似性所预期的那样。VCD是序列依赖性的。在所研究的脱水条件下，聚（dA-dT）·聚（dA-dT）、聚（dA）·聚（dT）和高A-T含量的天然DNA具有与其他DNA不同的带状形状，这与聚（rA）·聚（rU）的带状形状相似。聚（dG-dC）·聚（dG-dC）在高醇条件下不形成A型，而是具有与其高盐诱导的Z型非常相似的VCD光谱。两种形式的耦合振荡器VCD计算结果的差异表明了实验中观察到的A型和B型DNA VCD之间的定性差异。