FIG. 2.

Dependence of the activities of various mutants of E. coli UMP kinase on UTP (A) and GTP (B). The reaction medium buffered with Tris-HCl (pH 8) is described in Materials and Methods. The concentrations of ATP (1 mM) and UMP (0.1 mM [A] and 1 mM [B]) were kept constant; 100% corresponds to the activity of each mutant in the absence of effectors. ○, R62H; ▵, D77N; □, D146N; ⧫, D159N; ▪, D168N; ▴, D174N; ◊, D201N.