Wang S, Kool E T
Department of Chemistry, University of Rochester, NY 14627, USA.
Nucleic Acids Res. 1995 Apr 11;23(7):1157-64. doi: 10.1093/nar/23.7.1157.
Described is a systematic study of the effects of varied backbone structure on the stabilities of pyr.pur.pyr triple helices. The effects were measured using six circular 34 base oligonucleotides containing DNA (D), RNA (R) and/or 2'-O-methyl-RNA (M) residues designed to bind a complementary single-stranded purine target strand by triple helix formation. Eighteen different backbone combinations were studied at pH 5.5 and 7.0 by optical melting experiments and the results compared with the stabilities of the corresponding Watson-Crick duplexes. When the target purine strand is DNA, all circles form pH-dependent triple helical complexes which are considerably stronger than the duplexes alone. When RNA is the target, five of the nine complexes studied are of the pH-dependent triplex type and the other four complexes are not significantly stronger than the corresponding duplexes. The results are useful in the design of the highest affinity ligands for single- and double-stranded DNAs and RNAs and also point out novel ways to engender DNA- or RNA-selective binding.
本文描述了一项关于不同主链结构对嘧啶-嘌呤-嘧啶三链螺旋稳定性影响的系统研究。通过使用六种含有DNA（D）、RNA（R）和/或2'-O-甲基-RNA（M）残基的34个碱基的环状寡核苷酸来测量这些影响，这些寡核苷酸旨在通过三链螺旋形成与互补的单链嘌呤靶链结合。通过光学熔解实验在pH 5.5和7.0条件下研究了18种不同的主链组合，并将结果与相应的沃森-克里克双链体的稳定性进行了比较。当靶嘌呤链是DNA时，所有环状物都会形成pH依赖性的三链螺旋复合物，其强度明显强于单独的双链体。当RNA作为靶标时，所研究的九种复合物中有五种是pH依赖性三链体类型，另外四种复合物并不比相应的双链体明显更强。这些结果对于设计与单链和双链DNA及RNA具有最高亲和力的配体很有用，并且还指出了产生DNA或RNA选择性结合的新方法。
