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  • Title: Investigation of the structural basis for thermodynamic stabilities of tandem GU wobble pairs: NMR structures of (rGGAGUUCC)2 and (rGGAUGUCC)2.
    Author: McDowell JA, He L, Chen X, Turner DH.
    Journal: Biochemistry; 1997 Jul 01; 36(26):8030-8. PubMed ID: 9201950.
    Abstract:
    The symmetric, tandem GU mismatch motifs, and , which only differ in the mismatch order, have an average difference in thermodynamic stability of 2 kcal/mol at 37 degrees C. Thermodynamic studies of duplexes containing these motifs indicate the effect is largely localized to the mismatches and adjacent base pairs. The three-dimensional structures of two representative duplexes, (rGGAGUUCC)2 and (rGGAUGUCC)2, were determined by two-dimensional NMR and a simulated annealing protocol. Local deviations are similar to other intrahelical GU mismatches with little effect on backbone torsion angles and a slight overtwisting between the base pair 5' of the G of the mismatch and the mismatch itself. Comparisons of the resulting stacking patterns along with electrostatic potential maps suggest that interactions between highly negative electrostatic regions between base pairs may play a role in the observed thermodynamic differences.
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