The Role of Ionic Backbones in RNA Structure: An Unusually Stable Non-Watson-Crick Duplex of a Nonionic Analog in an Apolar Medium
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- 作者：Christoph Steinbeck and Clemens Richert
- 刊名：Journal of the American Chemical Society
- 出版年：1998
- 出版时间：November 18, 1998
- 年：1998
- 卷：120
- 期：45
- 页码：11576 - 11580
- 全文大小：115K
- 年卷期：v.120,no.45(November 18, 1998)
- ISSN：1520-5126
文摘
The solution structure of a dimethylenesulfone-linked analogue of the RNA dimer UPC was determinedusing two-dimensional NMR and restrained molecular dynamics. In CDCl3, the RNA analogue forms a parallelduplex with a single U:U base pair and roughly antiparallel orientation of the two ribose rings within eachstrand. A hydrogen bonding network stabilizing this duplex was indirectly deduced from the NMR data.Besides the two-pronged hydrogen bonding between the uridines, this network includes two hydrogen bondsfrom the ribose hydroxyls of one strand to O2 of the cytosine bases of the opposite strand, and intrastrandhydrogen bonds from the 2' hydroxyls of the 5'-terminal residues to hydroxyls of the 3'-terminal residue. Themelting point of the duplex determined via NMR chemical shift analysis was found to be 91 
C for a 11 mMsolution in 1,1,2,2-tetrachloroethane-d2. Based on van't Hoff analysis of the available UV melting data in1,2-dichloroethane, duplex formation is associated with a 
S of -47 cal K-1 mol-1 and a H of -22 kcalmol-1. The observation that an RNA analogue rendered nonionic and removed from an aqueous environmentforms an exceptionally stable non-Watson-Crick duplex with backbone-to-nucleobase and backbone-to-backbone hydrogen bonds suggests that a charged backbone and the solubility in aqueous medium that itconveys are important for limiting the repertoire of strand-strand interactions of oligoribonucleotides.
C for a 11 mMsolution in 1,1,2,2-tetrachloroethane-d2. Based on van't Hoff analysis of the available UV melting data in1,2-dichloroethane, duplex formation is associated with a S of -47 cal K-1 mol-1 and a H of -22 kcalmol-1. The observation that an RNA analogue rendered nonionic and removed from an aqueous environmentforms an exceptionally stable non-Watson-Crick duplex with backbone-to-nucleobase and backbone-to-backbone hydrogen bonds suggests that a charged backbone and the solubility in aqueous medium that itconveys are important for limiting the repertoire of strand-strand interactions of oligoribonucleotides.