Figure 4.
Figure 4 Polymerase active site with observed DNA and
modelled dTTP. The position of dTTP (violet) was based on the
-polymerase
complex18, adjusted such that the base ring stacks with the
primer and one oxygen from each phosphate group was within 3 ?
of the observed metal ion (gold). The sugar pucker of the primer
terminus was made C3'-endo, which shifted its 3'-OH to within
1.7 ? of the modelled -phosphate
of the dTTP. A second metal ion (violet) was modelled to be
within 3 ? of the 3'-OH of the primer, the -phosphate
group, and residues Asp 830 and Glu 831. The observed 5'
template overhang cannot accept an incoming dNTP without a
conformational change of the O helix.
-polymerase
complex18, adjusted such that the base ring stacks with the
primer and one oxygen from each phosphate group was within 3 ?
of the observed metal ion (gold). The sugar pucker of the primer
terminus was made C3'-endo, which shifted its 3'-OH to within
1.7 ? of the modelled 
-phosphate
of the dTTP. A second metal ion (violet) was modelled to be
within 3 ? of the 3'-OH of the primer, the