1G3A

STRUCTURE OF RNA DUPLEXES (CIGCGICG)2


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Submitted: 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Stability and structure of RNA duplexes containing isoguanosine and isocytidine.

Chen, X.Kierzek, R.Turner, D.H.

(2001) J.Am.Chem.Soc. 123: 1267-1274


  • PubMed Abstract: 
  • Isoguanosine (iG) and isocytidine (iC) differ from guanosine (G) and cytidine (C), respectively, in that the amino and carbonyl groups are transposed. The thermodynamic properties of a set of iG, iC containing RNA duplexes have been measured by UV op ...

    Isoguanosine (iG) and isocytidine (iC) differ from guanosine (G) and cytidine (C), respectively, in that the amino and carbonyl groups are transposed. The thermodynamic properties of a set of iG, iC containing RNA duplexes have been measured by UV optical melting. It is found that iG-iC replacements usually stabilize duplexes, and the stabilization per iG-iC pair is sequence-dependent. The sequence dependence can be fit to a nearest-neighbor model in which the stabilities of iG--iC pairs depend on the adjacent iG--iC or G--C pairs. For 5'-CG-3'/3'-GC-5' and 5'-GG-3'/3'-CC-5' nearest neighbors, the free energy differences upon iG-iC replacement are smaller than 0.2 kcal/mol at 37 degrees C, regardless of the number of replacements. For 5'-GC-3'/3'-CG-5', however, each iG--iC replacement adds 0.6 kcal/mol stabilizing free energy at 37 degrees C. Stacking propensities of iG and iC as unpaired nucleotides at the end of a duplex are similar to those of G and C. An NMR structure is reported for r(CiGCGiCG)(2) and found to belong to the A-form family. The structure has substantial deviations from standard A-form but is similar to published NMR and/or crystal structures for r(CGCGCG)(2) and 2'-O-methyl (CGCGCG)(2). These results provide benchmarks for theoretical calculations aimed at understanding the fundamental physical basis for the thermodynamic stabilities of nucleic acid duplexes.


    Organizational Affiliation

    Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsLengthOrganism
5'-R(*CP*(IG)P*CP*GP*(IC)P*G)-3'A,B6N/A
Small Molecules
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
IC
Query on IC
A, B
RNA LINKINGC9 H14 N3 O8 PC
IG
Query on IG
A, B
RNA LINKINGC10 H14 N5 O8 PG
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Submitted: 

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-08-01
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance