ChemInform Abstract: NUCLEAR MAGNETIC RESONANCE STUDIES OF CATECHOLAMINES. TERNARY COMPLEXES WITH ADENOSINE 5′-TRIPHOSPHATE AND DIVALENT METAL IONS IN AQUEOUS SOLUTION

1978 ◽  
Vol 9 (33) ◽  
Author(s):  
J. GRANOT
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Metal Ions ◽  
Divalent Metal ◽  
Ternary Complexes ◽  
Divalent Metal Ions ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

A cooperative conformational change in duplex DNA induced by Zn2+ and other divalent metal ions

1993 ◽  
Vol 71 (3-4) ◽  
pp. 162-168 ◽  
Author(s):  
Jeremy S. Lee ◽  
Laura J. P. Latimer ◽  
R. Stephen Reid
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Metal Ions ◽  
Conformational Change ◽  
Divalent Metal ◽  
Proton Nuclear Magnetic Resonance ◽  
Duplex Dna ◽  
Divalent Metal Ions ◽  
Base Pairs ◽  
Nuclear Magnetic

Zn2+ and some other divalent metal ions bind to duplex DNA at pHs above 8 and cause a conformational change. This new structure does not bind ethidium, allowing the development of a rapid fluorescence assay. All duplex DNAs, regardless of sequence or G∙C content, can form this structure. The rate of formation shows a strong dependence on temperature, pH, and Zn2+ concentration; at 20 °C, 1 mM Zn2+, and pH 8.6 the dismutation is half complete in 30 min. Addition of EDTA causes rapid reversion to 'B' DNA, showing that the new conformation retains two strands that are antiparallel. Unlike the ultraviolet or circular dichroism spectra, the nuclear magnetic resonance spectrum was informative since the imino protons of both A∙T and G∙C base pairs are lost upon addition of a stoichiometric amount of Zn2+. The pitch of the helix was estimated from gel electrophoresis of circular DNAs in the presence of Zn2+ and it contains at least 5% fewer base pairs per turn than 'B' DNA. The transformation is cooperative and shows hysteresis, suggesting that this is a distinct structure and not simply a minor variant of 'B' DNA. It is proposed to call this new structure 'M' DNA because of the intimate involvement of metal ions.Key words: DNA conformation, cooperative transition, ethidium binding, divalent metal ions, proton nuclear magnetic resonance.

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