posted on 2015-06-25, 00:00authored byGiovanni Villani
The effects of the addition of one
(hemimethylation) or two (methylation)
methyl groups on the 10 different couples of base pairs of DNA (three
dimers of A-T, three of C-G, and four mixed A-T and C-G complexes)
has been studied. Changes in the main static properties (energy, structure,
atomic charges) and dynamics (movement of hydrogen atoms from one
base to the other) have been considered and analyzed. The results
of this study support the idea that the quantitative effects of the
methylation of these complexes depend on the specific system under
consideration and on the H-bridge studied. In any case, some general
behavior can be highlighted. In particular, the relationship between
the transfer of hydrogen atoms between the bases (with the possible
generation of mutation points) and the methylation can be schematized
in the two most important methylated bases: adenine and cytosine.
A different behavior has been found in these two cases, and we suggest
that this could be related to the different amounts of these methylated
systems in prokaryotes and eukaryotes. In particular, this different
behavior could explain why adenine methylation is present mainly in
the bacteria and cytosine methylation is present in more complex organisms.