Cain R J, Zuiderweg E R, Glick G D
Department of Chemistry, University of Michigan, Ann Arbor 48109-1055, USA.
Nucleic Acids Res. 1995 Jun 25;23(12):2153-60. doi: 10.1093/nar/23.12.2153.
The solution structures of a 21 base long DNA hairpin derived from the ColE1 cruciform, and an analog possessing a disulfide cross-link bridging the terminal bases, have been determined by NMR spectroscopy. The 8 bp long stem of these sequences adopts a B-form helix whereas the five base long single-stranded loop appears to be flexible and cannot be represented by a unique static conformation. NOESY cross-peak volumes, proton and phosphorus chemical shifts, and both homo- and heteronuclear coupling constants for the cross-linked hairpin are virtually identical to those measured for the unmodified sequence, even for the residues that are proximal to the cross-link. These results indicate that both hairpins are structurally isomorphous. Because this cross-link can be incorporated site specifically in a sequence independent manner, and does not appear to alter native conformation, it should prove broadly applicable in studies of DNA structure and function.
通过核磁共振光谱法确定了源自ColE1十字形结构的21个碱基长的DNA发夹以及具有连接末端碱基的二硫键交联的类似物的溶液结构。这些序列8个碱基长的茎采用B型螺旋，而5个碱基长的单链环似乎是灵活的，不能用独特的静态构象表示。交联发夹的NOESY交叉峰体积、质子和磷化学位移以及同核和异核耦合常数与未修饰序列测量的值几乎相同，即使对于靠近交联的残基也是如此。这些结果表明两个发夹在结构上是同构的。由于这种交联可以以序列独立的方式位点特异性地掺入，并且似乎不会改变天然构象，因此它应该在DNA结构和功能研究中具有广泛的适用性。
