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| - | '''Structural rationalization of a large difference in RNA affinity despite a small difference in chemistry between two 2'-O-modified nucleic acid analogs'''
| + | ===Structural rationalization of a large difference in RNA affinity despite a small difference in chemistry between two 2'-O-modified nucleic acid analogs=== |
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| - | ==Overview==
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| - | Chemical modification of nucleic acids at the 2'-position of ribose has generated antisense oligonucleotides (AONs) with a range of desirable properties. Electron-withdrawing substituents such as 2'-O-[2-(methoxy)ethyl] (MOE) confer enhanced RNA affinity relative to that of DNA by conformationally preorganizing an AON for pairing with the RNA target and by improving backbone hydration. 2'-Substitution of the ribose has also been shown to increase nuclease resistance and cellular uptake via changes in lipophilicity. Interestingly, incorporation of either 2'-O-[2-(methylamino)-2-oxoethyl]- (NMA) or 2'-O-(N-methylcarbamate)-modified (NMC) residues into AONs has divergent effects on RNA affinity. Incorporation of 2'-O-NMA-T considerably improves RNA affinity while incorporation of 2'-O-NMC-T drastically reduces RNA affinity. Crystal structures at high resolution of A-form DNA duplexes containing either 2'-O-NMA-T or 2'-O-NMC-T shed light on the structural origins of the surprisingly large difference in stability given the relatively minor difference in chemistry between NMA and NMC. NMA substituents adopt an extended conformation and use either their carbonyl oxygen or amino nitrogen to trap water molecules between phosphate group and sugar. The conformational properties of NMA and the observed hydration patterns are reminiscent of those found in the structures of 2'-O-MOE-modified RNA. Conversely, the carbonyl oxygen of NMC and O2 of T are in close contact, providing evidence that an unfavorable electrostatic interaction and the absence of a stable water structure are the main reasons for the loss in thermodynamic stability as a result of incorporation of 2'-O-NMC-modified residues.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_15547979}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15547979 is the PubMed ID number. |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Sethaphong, L.]] | | [[Category: Sethaphong, L.]] |
| | [[Category: Rna mimetic methylamino amide analog]] | | [[Category: Rna mimetic methylamino amide analog]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:32:21 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 09:46:07 2008'' |
Revision as of 06:46, 28 July 2008
Template:STRUCTURE 1xux
Structural rationalization of a large difference in RNA affinity despite a small difference in chemistry between two 2'-O-modified nucleic acid analogs
Template:ABSTRACT PUBMED 15547979
About this Structure
Full crystallographic information is available from OCA.
Reference
Structural rationalization of a large difference in RNA affinity despite a small difference in chemistry between two 2'-O-modified nucleic acid analogues., Pattanayek R, Sethaphong L, Pan C, Prhavc M, Prakash TP, Manoharan M, Egli M, J Am Chem Soc. 2004 Nov 24;126(46):15006-7. PMID:15547979
Page seeded by OCA on Mon Jul 28 09:46:07 2008
