4f2x

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=3CO:COBALT+(III)+ION'>3CO</scene>, <scene name='pdbligand=NCO:COBALT+HEXAMMINE(III)'>NCO</scene>, <scene name='pdbligand=XTF:[(1R,4R,5S,6R)-5-FLUORO-6-HYDROXY-4-(5-METHYL-2,4-DIOXO-3,4-DIHYDROPYRIMIDIN-1(2H)-YL)CYCLOHEX-2-EN-1-YL]METHYL+DIHYDROGEN+PHOSPHATE'>XTF</scene></td></tr>

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== Publication Abstract from PubMed ==

We report the design and synthesis of 2'-fluoro cyclohexenyl nucleic acid (F-CeNA) pyrimidine phosphoramidites and the synthesis and biophysical, structural, and biological evaluation of modified oligonucleotides. The synthesis of the nucleoside phosphoramidites was accomplished in multigram quantities starting from commercially available methyl-d-mannose pyranoside. Installation of the fluorine atom was accomplished using nonafluorobutanesulfonyl fluoride, and the cyclohexenyl ring system was assembled by means of a palladium-catalyzed Ferrier rearrangement. Installation of the nucleobase was carried out under Mitsunobu conditions followed by standard protecting group manipulations to provide the desired pyrimidine phosphoramidites. Biophysical evaluation indicated that F-CeNA shows behavior similar to that of a 2'-modified nucleotide, and duplexes with RNA showed slightly lower duplex thermostability as compared to that of the more rigid 3'-fluoro hexitol nucleic acid (FHNA). However, F-CeNA modified oligonucleotides were significantly more stable against digestion by snake venom phosphodiesterases (SVPD) as compared to unmodified DNA, 2'-fluoro RNA (FRNA), 2'-methoxyethyl RNA (MOE), and FHNA modified oligonucleotides. Examination of crystal structures of a modified DNA heptamer duplex d(GCG)-T*-d(GCG):d(CGCACGC) by X-ray crystallography indicated that the cyclohexenyl ring system exhibits both the (3)H(2) and (2)H(3) conformations, similar to the C3'-endo/C2'-endo conformation equilibrium seen in natural furanose nucleosides. In the (2)H(3) conformation, the equatorial fluorine engages in a relatively close contact with C8 (2.94 A) of the 3'-adjacent dG nucleotide that may represent a pseudo hydrogen bond. In contrast, the cyclohexenyl ring of F-CeNA was found to exist exclusively in the (3)H(2) (C3'-endo like) conformation in the crystal structure of the modified A-form DNA decamer duplex [d(GCGTA)-T*-d(ACGC)](2.) In an animal experiment, a 16-mer F-CeNA gapmer ASO showed similar RNA affinity but significantly improved activity compared to that of a sequence matched MOE ASO, thus establishing F-CeNA as a useful modification for antisense applications.

Synthesis and Antisense Properties of Fluoro Cyclohexenyl Nucleic Acid (F-CeNA), a Nuclease Stable Mimic of 2'-Fluoro RNA.,Seth PP, Yu J, Jazayeri A, Pallan PS, Allerson CR, Ostergaard ME, Liu F, Herdewijn P, Egli M, Swayze EE J Org Chem. 2012 May 18. PMID:22591005<ref>PMID:22591005</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

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