Sequence - Selective Binding of Transition Metal Complexes to DNA - Metal Complex-DNA Interactions - page 12

Figure 1.7 Line-broadening versus Mn 2+ /Duplex ratio of the H8 resonances of the guanosines
5 ) for comparison.

(a) d(TATGGTACCATA) 2 ; (b) d(TATGGATCCATA) 2 ; (c) d(TATGGCCATA) 2 . (J. Vinje, J.A.
Parkinson, P.J. Sadler, T. Brown, E. Sletten, Sequence-selective metalation of double-helical
oligodeoxyribonucleotides with PtII, MnII and ZnII ions. Chem. Eur. J. , 2003, 9 , 1620-1630.
Copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reproduced with permission.)

′ -G4 ( * ) and 3 ′ -G5 ( ) with the terminal adenine H8 protons (

preference for terminal base residues. Based on the NMR results from several DNA
sequences the d(GGCGCC) duplex is expected to bind preferentially to the 5 ′ - G

in the 5 -GC step should have negligible affi nity,

in agreement with the X-ray result. 37 Crystallographic data of a metal-DNA complex
containing an internal GG step would probably show binding at this site.
Table 1.1 is a compilation of available line-broadening data including both
controlled titration experiments and the effect of paramagnetic impurities (reversed
by addition of EDTA). One may notice that only Gs in the context G-purine exhibit
maximum broadening. For sequence no. 6, which contains no G-purine step, the
5

′ -GG step and that the 5 ′ - G in the 5 ′

-GT step exhibits maximum broadening.
A close inspection of Table 1.1 reveals that the line-broadening of 5

′ -G-H8 resonance in the context of the 5 ′

′ - G - H8 follows

a consistent pattern, where the infl uence on the 5 ′ - G - H8 is dependent on the residue