Figure 3
Inhibitors suggest the presence of purinergic receptor(s) in P. berghei (A) and P. yoelii (B). Rate of peptide hydrolysis induced by ATP (50 μM) as measured by fluorescence after incubation with suramin (50 μM) (1.1 ± 0.04, n = 7, P = 0.0002 and 1.0 ± 0.07, n = 7, P = 0.0006, respectively), PPADS (50 μM) (1.1 ± 0.08, n = 12, P = 0.0008 and 1.4 ± 0.063, n = 6, P = 0.791, respectively) or KN-62 (10 μM) (1.3 ± 0.025, n = 13, P = 0.001). P values were calculated by comparison with the ATP (50 μM) data (1.5 ± 0.067, n = 9 and 1.4 ± 0.062, n = 12, respectively). Effects of ATP on FRET peptide Abz-AIKFFARQ-EDDnp (10 μM) hydrolysis were observed after 30 min incubation of isolated parasites (108 cells ml-1) with the pharmacological agents in MOPS buffer with 1 mM calcium in a 1 ml cuvette.. The fluorescence was measured continuously (acquisition rate: every 0.5 seconds) for 400 seconds.