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Structures of DNA double helix
Author(s) -
Sarma Ramaswamy H.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560220709
Subject(s) - helix (gastropod) , oligonucleotide , dna , sequence (biology) , propeller , crystallography , resonance (particle physics) , physics , chemistry , biology , atomic physics , biochemistry , paleontology , marine engineering , snail , engineering
Nuclear magnetic resonance data are presented which show that poly(dG‐dC)·poly(dG‐dC) in solution under high salt conditions takes up the left‐handed Z‐DNA conformation and that in low salt solutions it is predominantly the Arnott‐Hukins B form. In both forms the G‐C pairs are not propeller twisted, i.e., they are flat. On the other hand, the AATT segments in oligonucleotide double helices tend to be propeller twisted, and the AT domains conform to a structure similar to that of Levitt and Dickerson models. These studies indicate that under solution conditions the DNA double helix, depending upon sequence, can take up a variety of spatial configurations. Data in the literature about conformational transitions and interconnections are reviewed, and we examine the available evidence for the presence of left‐handed Z‐DNA in a chromosome.