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'''Cobalt hexammine induced tautomeric shift in Z-DNA: the structure of d(CGCGCA).d(TGCGCG) in two crystal forms''' | '''Cobalt hexammine induced tautomeric shift in Z-DNA: the structure of d(CGCGCA).d(TGCGCG) in two crystal forms''' | ||
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==About this Structure== | ==About this Structure== | ||
Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XA2 OCA]. | |||
==Reference== | ==Reference== | ||
Cobalt hexammine induced tautomeric shift in Z-DNA: the structure of d(CGCGCA)*d(TGCGCG) in two crystal forms., Thiyagarajan S, Rajan SS, Gautham N, Nucleic Acids Res. 2004 Nov 8;32(19):5945-53. Print 2004. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15534365 15534365] | Cobalt hexammine induced tautomeric shift in Z-DNA: the structure of d(CGCGCA)*d(TGCGCG) in two crystal forms., Thiyagarajan S, Rajan SS, Gautham N, Nucleic Acids Res. 2004 Nov 8;32(19):5945-53. Print 2004. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15534365 15534365] | ||
[[Category: Gautham, N.]] | [[Category: Gautham, N.]] | ||
[[Category: Rajan, S S.]] | [[Category: Rajan, S S.]] | ||
[[Category: Thiyagarajan, S.]] | [[Category: Thiyagarajan, S.]] | ||
[[Category: | [[Category: Double helix]] | ||
[[Category: | [[Category: Z-dna]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 14:46:02 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 14:46, 3 May 2008
Cobalt hexammine induced tautomeric shift in Z-DNA: the structure of d(CGCGCA).d(TGCGCG) in two crystal forms
OverviewOverview
We report here the crystal structure of the DNA hexamer duplex d(CGCGCA)*d(TGCGCG) at 1.71 A resolution. The crystals, in orthorhombic space group, were grown in the presence of cobalt hexammine, a known inducer of the left-handed Z form of DNA. The interaction of this ion with the DNA helix results in a change of the adenine base from the common amino tautomeric form to the imino tautomer. Consequently the A:T base pair is disrupted from the normal Watson-Crick base pairing to a 'wobble' like base pairing. This change is accommodated easily within the helix, and the helical parameters are those expected for Z-DNA. When the cobalt hexammine concentration is decreased slightly in the crystallization conditions, the duplex crystallizes in a different, hexagonal space group, with two hexamer duplexes in the asymmetric unit. One of these is situated on a crystallographic 6-fold screw axis, leading to disorder. The tautomeric shift is not observed in this space group. We show that the change in inter-helix interactions that lead to the two different space groups probably arise from the small decrease in ion concentration, and consequently disordered positions for the ion.
About this StructureAbout this Structure
Full crystallographic information is available from OCA.
ReferenceReference
Cobalt hexammine induced tautomeric shift in Z-DNA: the structure of d(CGCGCA)*d(TGCGCG) in two crystal forms., Thiyagarajan S, Rajan SS, Gautham N, Nucleic Acids Res. 2004 Nov 8;32(19):5945-53. Print 2004. PMID:15534365 Page seeded by OCA on Sat May 3 14:46:02 2008