4bna
From Proteopedia
REVERSIBLE BENDING AND HELIX GEOMETRY IN A B-DNA DODECAMER: CGCGAATTBRCGCG
Overview
A double-helical B-DNA dodecamer has been analyzed by single crystal x-ray diffraction methods and refined independently in four variants: sequence CGCGAATTCGCG at 20 degrees C and at 16 K, and CGCGAATTBrCGCG in 60% methylpentanediol at 20 and at 7 degrees C. The first three forms show a 14-19 degrees bend in overall helix axis, but the fourth is straight and unbent. Detailed comparisons of the various forms have led to a better understanding of helix geometry and bending. Structural principles can be understood best if organized under four headings: 1) intrinsic geometry of the sugar rings, 2) stacking and relative motion of base pairs, 3) geometry of the connecting phosphate backbone, and 4) mechanics of bending in B-DNA. The observed bending is neither completely localized nor smooth and continuous, but an intermediate compromise that can be termed "annealed kinking."
About this Structure
Full crystallographic information is available from OCA.
Reference
Reversible bending and helix geometry in a B-DNA dodecamer: CGCGAATTBrCGCG., Fratini AV, Kopka ML, Drew HR, Dickerson RE, J Biol Chem. 1982 Dec 25;257(24):14686-707. PMID:7174662 Page seeded by OCA on Sun May 4 22:21:27 2008
