Figure 1.

Space filling models of ScOMPDC from yeast.¹⁸ The structure on the left is the open unliganded form of ScOMPDC (PDB entry 1DQW), and the structure on the right shows the complex with 6-hydroxyuridine 5′-monophosphate (PDB entry 1DQX). Two colored flexible loops close to form the active site cage: Pro202–Val220, on the left-hand side of each structure, interact with the substrate dianion, and Glu152–Thr165, on the right-hand side, interact with the pyrimidine ring. The guanidine side chain of R235, at the base of the left-hand loop, is colored green.