Statistical analysis of DNA duplex structures in solution derived by high resolution NMR

摘要: An initial statistical analysis has been performed on the helical parameters for solution structures of three DNA duplexes recently solved in this laboratory by proton NMR. Local conformations these belong to B family forms; nevertheless they display a strong sequence-dependent heterogeneity akin that found single crystals and theoretical calculations. However, average as well their variations are quite different short fragments crystal. Average twist NMR-refined oligonucleotides is 34.6°, remarkable agreement with independent solution-state data, while 36° crystals. Other characteristic features negative slide, systematically open minor groove (for almost all sequences), decreased rise. The latter, rather unexpected finding, correlated surprisingly non-flatness Watson-Crick base pairs. Deviations pairs from planarity proved be significant source conformational variability; particular importance stagger, which often missed structural DNA. Several new have introduced dinucleotide steps, characterizing non-planar geometries constituent pairs; show degree correlation traditional step (twist, tillt roll, shift, rise). Many observed structures; variation roll slide occurs according “Calladine’s rules”, appears oppose them. larger set needed complete sequence dependence conformation.