1g3a

STRUCTURE OF RNA DUPLEXES (CIGCGICG)2

spinqualitylabelsall models 1g3a Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1g3a is a 2 chain structure. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Ligands: IC, IG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed 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. Stability and structure of RNA duplexes containing isoguanosine and isocytidine.,Chen X, Kierzek R, Turner DH J Am Chem Soc. 2001 Feb 21;123(7):1267-74. PMID:11456697 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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