Insights from crystal structures into the opposite effects on RNA affinity caused by the s- and R-6'-methyl backbone modifications of 3'-fluoro hexitol nucleic Acid.
Pallan, P.S., Yu, J., Allerson, C.R., Swayze, E.E., Seth, P., Egli, M.(2012) Biochemistry 51: 7-9
- PubMed: 22229409 
- DOI: https://doi.org/10.1021/bi201810r
- Primary Citation of Related Structures:  
3V06, 3V07 - PubMed Abstract: 
Locked nucleic acid (LNA) analogues with 2',4'-bridged sugars show promise in antisense applications. S-5'-Me-LNA has high RNA affinity, and modified oligonucleotides show weakened immune stimulation in vivo. Conversely, an R-5'-methyl group dramatically lowers RNA affinity. To test the effects of S- and R-6'-methyl groups on 3'-fluoro hexitol nucleic acid (FHNA) stability, we synthesized S- and R-6'-Me-FHNA thymidine and incorporated them into oligo-2'-deoxynucleotides. As with LNA, S-6'-Me is stabilizing whereas R-6'-Me is destabilizing. Crystal structures of 6'-Me-FHNA-modified DNAs explain the divergent consequences for stability and suggest convergent origins of these effects by S- and R-6'-Me (FHNA) [-5'-Me (LNA and RNA)] substituents.
Organizational Affiliation: 
Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, Tennessee 37232, United States.