Differential rates of extracellular mononucleotide degradation by ecto-5′-nucleotidase from human umbilical vein endothelial cells and HeLa cells
| . | HUVECs . | HUVECs + α,β-methylene–ADP . | HeLa . | HeLa + α,β-methylene–ADP . |
|---|---|---|---|---|
| dAMP | 16.7 ± 7.2 | 200.0 ± 0.5 | 64.0 ± 26.7 | 138.2 ± 24.9 |
| dGMP | 9.3 ± 5.7 | 198.3 ± 5.3 | 128.0 ± 18.0 | 114.0 ± 13.0 |
| TMP | 45.5 ± 13.0 | 197.5 ± 4.5 | 130.5 ± 16.6 | 154.1 ± 25.2 |
| dAMPS | 176.0 ± 25.2 | 200.0 ± 1.0 | 200.0 ± 1.6 | 200.0 ± 2.2 |
| dGMPS | 188.2 ± 17.6 | 199.5 ± 3.4 | 197.1 ± 21.2 | 200.0 ± 1.2 |
| TMPS | 136.7 ± 9.1 | 201.3 ± 6.3 | 177.3 ± 15.1 | 197.2 ± 8.1 |
| . | HUVECs . | HUVECs + α,β-methylene–ADP . | HeLa . | HeLa + α,β-methylene–ADP . |
|---|---|---|---|---|
| dAMP | 16.7 ± 7.2 | 200.0 ± 0.5 | 64.0 ± 26.7 | 138.2 ± 24.9 |
| dGMP | 9.3 ± 5.7 | 198.3 ± 5.3 | 128.0 ± 18.0 | 114.0 ± 13.0 |
| TMP | 45.5 ± 13.0 | 197.5 ± 4.5 | 130.5 ± 16.6 | 154.1 ± 25.2 |
| dAMPS | 176.0 ± 25.2 | 200.0 ± 1.0 | 200.0 ± 1.6 | 200.0 ± 2.2 |
| dGMPS | 188.2 ± 17.6 | 199.5 ± 3.4 | 197.1 ± 21.2 | 200.0 ± 1.2 |
| TMPS | 136.7 ± 9.1 | 201.3 ± 6.3 | 177.3 ± 15.1 | 197.2 ± 8.1 |
Concentrations of the unchanged substrate are given. Ecto-enzymatic degradation of dNMP and dNMPS was measured in RPMI 1640 medium supplemented with 10% (HeLa) or 20% fetal bovine serum (HUVECs) 24 hours after addition of 200 μM mononucleotides or following 2-hour incubation with 100 μM α,β-methylene-ADP. Concentrations of the unchanged substrate in the extracellular medium subsamples were estimated from the peak areas obtained after high-performance liquid chromatography. Data points represent means ± SDs of at least 3 experiments.
ADP indicates adenosine 5′-diphosphate. Other abbreviations are explained in Table 1.