Chemistry Reference
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Figure 12.3
Molecular models of the interactions between [d(CGCGAATTCGCG)
2
] and
D
-
[Ru(bpy)
2
(m-GHK)]Cl
2
(A) and
L
-[Ru(bpy)
2
(m-GHK)]Cl
2
(B) refl ecting the average binding
of each complex to the oligonucleotide. (A. Myari, N.Hadjiliadis, A.Garoufi s, Synthesis and
characterization of the diastereomers
L
- and
D
-[Ru(bpy)
2
(m-bpy.Gly-His-L-His-L-Lys)]Cl
2
.
1
H
NMR studies on their interactions with the deoxynucleotide duplex d[5
′
-CGCGAATTCGCG-
3
],
Eur. J. Inorg. Chem
., 2004,
7
, 1435-1436. Copyright Wiley-VCH Verlag GmbH & Co.
KGaA. Reproduced with permission.)
′
interaction of the chimera with DNA, but the absence of signifi cant shifts of the
peptide functional groups (or their neighbouring protons) indicated that probably
no specifi c contact between peptide and the DNA bases was formed, rather an
electrostatic type of interaction was assumed. Photocleavage studies were also con-
ducted with the plasmid pUC19 and a 158 bp restriction fragment showing that both
diastereomers cleave DNA with similar effi ciency, attacking mainly the guanines of
the sequence probably by generating active oxygen species.
24
In an attempt to combine the notable cytotoxicity observed for chloro(polypyridyl)
ruthenium complexes
28
with the possible DNA recognition specifi city provided by
the peptide moiety, K. Karidi
et al.
synthesized the chloro-complex of the tethered
peptide [Ru(terpy)(4-CO
2
H - 4
- Mebpy - Gly - L - His - L - LysCONH
2
)Cl](PF
6
).
29
The
interactions of the ruthenium peptide complex with CT-DNA and plasmid DNA
were studied with various spectroscopic techniques, showing coordinative binding
of the ruthenium complex to DNA, after hydrolysis of the coordinated chloride, and
a preference for the bases guanine and cytosine over the bases thymine and adenine.
Electrostatic interactions between the complex cation and the polyanionic DNA
chain assisted this binding whereas DNA unwinding occurred in all cases with high
binding ratio (Ru/base) values (
r
′
0.3). Moreover, interaction of the peptide with
DNA was evidenced by
31
P NMR spectroscopy for the one of the two positional
isomers of the ruthenium complex.
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