TABLE 4

Effect of free Mg, free ATP, and ATP/Mg in the phosphorylation of pyrimidine nucleoside and analog monophosphates by recombinant human UMP/CMP kinase

The reactions were performed using two sets of ATP/Mg concentration combinations: Mg fixed to 2 mM and equal concentrations of ATP/Mg. As demonstrated in Fig. 5, the difference between ATP/Mg 0.5/2 mM and 0.5/0.5 mM, 5/2 mM and 2/2 mM, 5/5 mM and 2/2 mM revealed the effect of free Mg, free ATP, and ATP/Mg, respectively. All reactions were performed when the concentration of phosphate acceptor was 1 mM, except for gemcitabine-MP (dFdCMP), ddCMP, l-ddCMP, l-OddCMP, and l-SddCMP. Values are presented as mean ± standard deviation from at least two independent experiments.

Percentage of increase (↑) or inhibition (↓) (%)
Nucleoside or Analog Monophosphates Effect of Free Mg Effect of Free ATP Effect of ATP/Mg
CMP ↓ 29.2 ± 7.1 ↑ 4.3 ± 9 ↑ 10.2 ± 8.0
dCMP ↑ 70.2 ± 17.9 ↓ 73.6 ± 3.6 ↓ 29.1 ± 2.7
UMP ↓ 42.0 ± 8.4 ↓ 26.6 ± 11.7 ↑ 7.9 ± 17.6
dUMP ↑ 116.6 ± 57.9 ↓ 82.2 ± 17.1 ↓ 44.5 ± 7.4
FUMP ↓ 19.6 ± 5.3 ↓ 30.0 ± 14.4 ↑ 3.2 ± 2.2
FdUMP ↑ 54.4 ± 35.7 ↓ 80.1 ± 1.5 ↓ 27 ± 12.5
AraCMP ↑ 16.5 ± 1.7 ↓ 66.1 ± 1.3 ↓ 22.0 ± 6.1
dFdCMPa ↑ 75.4 ± 3.4 ↓ 64.6 ± 1.8 ↓ 20.0 ± 3.9
ddCMPb ↑ 83.7 ± 11.2 ↓ 38.2 ± 13.2 ↓ 21.0 ± 10.8
l-ddCMPb ↑ 50.4 ± 7.2 ↓ 50.8 ± 11.6 ↓ 16.5 ± 11.6
l-OddCMPb ↑ 40.0 ± 5.5 ↓ 39.8 ± 23.2 ↓ 10.8 ± 3.4
l-SddCMPb ↑ 60.1 ± 10.4 ↓ 56.1 ± 5.6 ↓ 12.7 ± 3.4
  • a The concentration of dFdCMP was 0.2 mM.

  • b The concentration of ddCMP, l-ddCMP, l-OddCMP, and l-SddCMP was 0.5 mM.