FIGURE 10.

Close-up views of the Tth UDGb-DNA active site interactions in the energy minimized structures. Tube trace of the protein is colored in tan. Uridine (U), inosine (I), and xanthosine (X), as well as amino acids Asp⁷⁵, Asn¹²⁰, and His¹⁹⁰, are colored by atom type. Water molecules are labeled in purple. Dashed lines indicate inferred hydrogen bonds or water association. A, modeled Tth UDGb-U interactions. B, modeled Tth UDGb-I interactions. C, modeled Tth UDGb-X interactions. D, chemical illustration of Tth UDGb-U interactions. E, chemical illustration of Tth UDGb-I interactions. F, chemical illustration of Tth UDGb-X interactions.