Fig. 4.
Close-up view of the hTDGcat-G·THF product complex. The enzyme is represented as a semitransparent surface, showing key residues in stick format. DNA is represented in stick format with the abasic strand colored green and the complementary strand colored yellow (oxygen red, nitrogen blue, phosphorus orange). Phosphates are labeled according to their position with respect to the target site (THF). Hydrogen bond interactions between the R275 side chain and the P2 and P-1 phosphates are indicated by black dashed lines. The orange dashed line indicates the “phosphate pinch,” where the distance between P2 and P-1 is reduced to 7.8 Å from an average of 12.7 Å for the DNA overall.