Fig. 5.
To determine initial reaction velocities, CD39 (10 ng) was incubated with high concentrations of substrates (25 to 200 μmol/L) for 10 min at 30 °C. In panel a, substrates were either ATP or N6-etheno-ATP and the downstream products (ADP + AMP or N6-etheno-ADP + N6-etheno-AMP) were measured. In panel b, substrates were either ADP or N6-etheno-ADP and the downstream products (AMP or N6-etheno-AMP) were measured. The experiment in panel c was similar to that described for panel b with the exception that the substrates were AMP or N6-etheno-AMP, the enzyme was CD73 (0.25 ng), and the measured products were adenosine and N6-etheno-ADO. eATP = N6-etheno-ATP; eADP = N6-etheno-ADP; eAMP = N6-etheno-AMP. Values represent means ± SDs