Figure 2.

Structure of the active sites of human TK1 (left) and vaccinia virus TK (right). Both the human and vaccinia virus enzymes co-purified with the allosteric effector, dTTP, which was resolved in the published three–dimensional structures of the enzymes. Shown is dTTP bound to the active site of both the human [43], and the viral enzyme [16]. (Figure provided by Debasish Chattopadhyay, University of Alabama at Birmingham).