Fig. 3.
Interactions of an incoming L-nucleotide with either the templating nucleotide dG or R517 in Polλ–DNA–L-nucleotide. (A and B) L-dCTP, (C and D) (–)3TC-TP, and (E and F) (–)FTC-TP. A, C, and E are in complexes A, whereas B, D, and F are in complexes M. Only two template nucleotides, the primer 3′-terminal nucleotide, and active site residues R517 and Y505 are displayed as sticks. Hydrogen bonds and the distance between the primer 3′-OH group and the α-phosphorus atom of an incoming L-nucleotide are presented as black dashed lines, with the numbers depicting their lengths in Å. The interactions between the triphosphate of an incoming L-nucleotide and the divalent metal ions at sites A and B, shown as green spheres, are also presented as black dashed lines. The Fo-Fc omit maps (3 σ level) for the incoming L-nucleotides are illustrated in light blue.