... following nine mutations: V106A, V106G, V106H, V106I, V106K, V106L, V106M, V106Q and V106T We then characterized the enzymatic properties of the mutant enzymes The apparent native sizes of the –ATP ... of dTMP formation and thymidine concentration Open symbols, +ATP forms; closed symbols, –ATP forms (A) Dimeric enzymes: V106WT, V106A, V106I and V106T; (B) tetrameric enzymes: V106G, V106H, V106K, ... enzymes, containing V106G, V106H, V106K, V106L and V106Q, have properties similar to V106M, i.e in both the absence and presence of ATP they have low K0.5 values for thymidine, % 0.3–1.2 lM, and Hill...