TABLE 2

Enzyme inhibition study of recombinant human UMP/CMP kinase: inhibition of UMP or dCMP phosphorylation by CMP

The enzyme inhibition studies were performed with either 0 to 100 μM of UMP or 0 to 1000 μM of dCMP in the presence of different concentrations of CMP. Reactions were performed with ATP/Mg concentrations either 0.1/2 or 2/2 mM, 2 mM DTT, and 10 mM NaF. The Ki values of CMP for inhibiting UMP or dCMP phosphorylation (Ki CMP on UMPK or Ki CMP dCMPK) were derived according to Figs. 2 and 3. The data are presented as mean with S.D. from at least three separate experiments. The Km values of CMP, as a reference to compare with Ki values, are from Table 1.

ATP/Mg Km CMPKi on UMPKKi on dCMPK
μM
0.1/2 mM 5 ± 2 7 ± 2 21 ± 2
2/2 mM 15 ± 6 12 ± 3 91 ± 19