详细信息    查看全文

• 作者：Martin Egli ; George Minasov ; Valentina Tereshko ; Pradeep S. Pallan ; Marianna Teplova ; Gopal B. Inamati ; Elena A. Lesnik ; Steve R. Owens ; Bruce S. Ross ; Thazha P. Prakash ; and Muthiah Manoharan
• 刊名：Biochemistry
• 出版年：2005
• 出版时间：June 28, 2005
• 年：2005
• 卷：44
• 期：25
• 页码：9045 - 9057
• 全文大小：680K
• 年卷期：v.44,no.25(June 28, 2005)
• ISSN：1520-4995

文摘

The syntheses of 10 new RNA 2'-O-modifications, their incorporation into oligonucleotides,and an evaluation of their properties such as RNA affinity and nuclease resistance relevant to antisenseactivity are presented. All modifications combined with the natural phosphate backbone lead to significantgains in terms of the stability of hybridization to RNA relative to the first-generation DNA phosphorothioates(PS-DNA). The nuclease resistance afforded in particular by the 2'-O-modifications carrying a positivecharge surpasses that of PS-DNA. However, small electronegative 2'-O-substituents, while enhancing theRNA affinity, do not sufficiently protect against degradation by nucleases. Similarly, oligonucleotidescontaining 3'-terminal residues modified with the relatively large 2'-O-[2-(benzyloxy)ethyl] substituentare rapidly degraded by exonucleases, proving wrong the assumption that steric bulk will generally improveprotection against nuclease digestion. To analyze the factors that contribute to the enhanced RNA affinityand nuclease resistance we determined crystal structures of self-complementary A-form DNA decamerduplexes containing single 2'-O-modified thymidines per strand. Conformational preorganization ofsubstituents, favorable electrostatic interactions between substituent and sugar-phosphate backbone, anda stable water structure in the vicinity of the 2'-O-modification all appear to contribute to the improvedRNA affinity. Close association of positively charged substituents and phosphate groups was observed inthe structures with modifications that protect most effectively against nucleases. The promising propertiesexhibited by some of the analyzed 2'-O-modifications may warrant a more detailed evaluation of theirpotential for in vivo antisense applications. Chemical modification of RNA can also be expected tosignificantly improve the efficacy of small interfering RNAs (siRNA). Therefore, the 2'-O-modificationsintroduced here may benefit the development of RNAi therapeutics.