Structure of d(CACGCG).d(CGCGTG) in crystals grown in the presence of ruthenium III hexammine chloride.
Hexammine ions are strong inducers of the transition from the B-form to the left-handed Z-form in DNA. Here the structure of d(CACGCG). d(CGCGTG) obtained from crystals grown from a drop containing [Ru(NH3)6]Cl3 is reported. The structure is clearly characterized as Z-DNA. When compared with the structure of d(CACGCG).d(CGCGTG)/MgCl2 and that of d(CGCGCG)2, subtle differences are seen, most noticeably in the water structure. Since stable well diffracting crystals grow easily in the presence of [Ru(NH3)6]Cl3 and since this ion is not visible in the electron density it is concluded that the ion plays a non-specific role in stabilizing Z-DNA.
Karthe
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P
Department of Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India. crystal@giasmd01.vsnl.net.in
Gautham
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N
D020029:Base Pairing; D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000187:drug effects*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D017975:Ruthenium Compounds / Q000494:pharmacology*
D009838:Oligodeoxyribonucleotides; D017975:Ruthenium Compounds; C031584:hexammineruthenium; D004247:DNA