Fig. 3.

When N⁶-etheno-ATP (a) and N⁶-etheno-AMP (b) were incubated for 30 min at 30 °C in the absence of ecto-nucleotidases, the only chromatographic peaks observed were intact N⁶-etheno-ATP and intact N⁶-etheno-AMP, respectively, thus indicating that N⁶-etheno-ATP and N⁶-etheno-AMP were chemically stable under these test conditions. When N⁶-etheno-ATP was incubated for 30 min at 30 °C in the presence of either 20 ng of rhCD39 (c), 80 ng of rhENPP-1 (d), 40 ng of rhENTPD2 (e), or 11 ng of rhENTPD3 (f), N⁶-etheno-ATP was essentially quantitatively converted to N⁶-etheno-AMP. When N⁶-etheno-AMP (g) was incubated for 30 min at 30 °C in the presence of rhCD73 (40 ng), all of the N⁶-etheno-AMP was recovered as N⁶-etheno-adenosine (ADO)