Nucleic Acids Research Advance Access published online on December 20, 2007
Nucleic Acids Research, doi:10.1093/nar/gkm880
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Chemistry |
2'-Methylseleno-modified oligoribonucleotides for X-ray crystallography synthesized by the ACE RNA solid-phase approach
Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck (CMBI), Leopold Franzens University, Innrain 52a, 6020 Innsbruck, Austria
*To whom correspondence should be addressed. Tel: +43 512 507 5210; Fax: 43 512 507 2892; Email: ronald.micura{at}uibk.ac.at
Received September 11, 2007. Revised October 1, 2007. Accepted October 1, 2007.
Site-specifically modified 2'-methylseleno RNA represents a valuable derivative for phasing of X-ray crystallographic data. Several successful applications in three-dimensional structure determination of nucleic acids, such as the Diels–Alder ribozyme, have relied on this modification. Here, we introduce synthetic routes to 2'-methylseleno phosphoramidite building blocks of all four standard nucleosides, adenosine, cytidine, guanosine and uridine, that are tailored for 2'-O-bis(acetoxyethoxy)methyl (ACE) RNA solid-phase synthesis. We additionally report on their incorporation into oligoribonucleotides including deprotection and purification. The methodological expansion of 2'-methylseleno labeling via ACE RNA chemistry is a major step to make Se-RNA generally accessible and to receive broad dissemination of the Se-approach for crystallographic studies on RNA. Thus far, preparation of 2'-methylseleno-modified oligoribonucleotides has been restricted to the 2'-O-[(triisopropylsilyl)oxy]methyl (TOM) and 2'-O-tert-butyldimethylsilyl (TBDMS) RNA synthesis methods.