Chemistry Reference
In-Depth Information
2
Thermodynamic Models of Metal
Ion - DNA Interactions
Vasil Bregadze , Eteri Gelagutashvili and Ketevan Tsakadze
2.1 Introduction
Recently the catalytic properties of DNA became of special interest to scientists. In
particular, attention has been drawn to photo-processes
1 - 7
and processes connected
with charge
8 - 15
and energy
16 - 18
transfers.
On one hand, transition - (G
↔
A, C
↔
T) and transversion - (A
↔
T , A
↔
C ,
G
T) type gene or point mutations, in rare cases, may lead to improve-
ment of one or another characteristic of the organism. They are essential steps for
artifi cial or natural selection in biology. On the other hand, more commonly, these
mutations cause transformation of the cells, or their death
19 - 20
. This fact fi nds its
application in medicine, specifi cally in chemotherapy and photo-chemotherapy.
The mutations that lead to death of the cells are initiated by anticancer drugs, which
often contain metals.
4 - 7,21 - 25
The structure of the DNA double helix offers carte blanche for transition-type
mutations via defects, such as wrong Watson-Crick pairs, where self-congruent
cooperative keto-enol and amino-imine tautomeric transitions, named double-
proton transfer (DPT), take place.
17
This is a property of cyclic structures in polar
molecules. The nucleotide pairs in DNA naturally present such cyclic structures
between complementary bases. The mechanism of DPT in a DNA duplex was fi rst
considered by Löwdin as early as in 1963.
26,27
It is assumed that approximately one
↔
C, G
↔
