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Alternating d(GA)n DNA sequences form antiparallel stranded homoduplexes stabilized by the formation of G.A base pairs.
Author(s) -
Huertas D.,
Bellsolell L.,
Casasnovas J.M.,
Coll M.,
Azorín F.
Publication year - 1993
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1993.tb06081.x
Subject(s) - antiparallel (mathematics) , guanine , base pair , stereochemistry , dna , crystallography , biology , protonation , hydrogen bond , chemistry , nucleotide , biochemistry , molecule , physics , ion , organic chemistry , quantum mechanics , magnetic field , gene
Alternating d(GA)n DNA sequences form antiparallel stranded homoduplexes which are stabilized by the formation of G.A pairs. Three base pairings are known to occur between adenine and guanine: AH+ (anti).G(syn), A(anti).G(anti) and A(syn).G(anti). Protonation of the adenine residues is not involved in the stabilization of this structure, since it is observed at any pH value from 8.3 to 4.5; at pH < or = 4.0 antiparallel stranded d(GA.GA) DNA is destabilized. The results reported in this paper strongly suggest that antiparallel stranded d(GA.GA) homoduplexes are stabilized by the formation of alternating A(anti).G(anti) and G(anti).A(syn) pairs. In this structure, all guanine residues are in the anti conformation with their N7 position freely accessible to DMS methylation. On the other hand, adenines in one strand adopt the anti conformation, with their N7 position also free for reaction, while those of the opposite strand are in the syn conformation, with their N7 position hydrogen bonded to the guanine N1 group of the opposite strand. A regular right‐handed helix can be generated using alternating G(anti).A(syn) and A(anti).G(anti) pairs.