Breaking up the dNTP-TS (dTTP-TS shown) for calculating the contributions of
the base and the triphosphate part separately, taking into consideration the
different dielectric environments. The dielectric constant ε used
for the calculations with the base in region I was 2. The sugar contribution
was found to be negligible and thus included as part of the
“protein” (region II), rather than as substrate (region I).
Due to the highly charged environment of the triphosphate-TS fragment, a
dielectric constant of 40 was used for this part of the molecule; note that
the O3′ atom of the primer was included in region I and thus is also
shown in this representation. The color scheme is according to atom type
(cyan [C], white [H], blue
[N], red [O], light brown
[P]); the bonds connecting the three parts of the dNTP are
represented in black.