TABLE 1.

Specific activities of PfPNP and PfADA in whole cell lysates of wild type and Δpfpnp lines

Whole cell parasite lysates were obtained from infected red blood cells that were saponin lysed before freeze-thawing. The substrates used were inosine, 5′-methylthioinosine (MTI), adenosine, and 5′-methylthioadenosine (MTA). When comparing the ADA specific activity of the WT parasite lines to the Δpfpnp lines the Student's t test showed no statistical difference in specific activity between the lines with both substrates (adenosine and MTA). The limit of detection for inosine was 1.1 nmol mg⁻¹ min⁻¹ and 0.8 nmol mg⁻¹ min⁻¹ for MTI, which represents ~20 fold increase above the background for the specific activity of PNP detected in the 3D7 and hrpII integrant lines for both substrates.

Specific activity
Parasite line	PNP		ADA
	Inosine	MTI	Adenosinea	MTAb
		nmol mg−1 min−1
3D7	23.0 ± 5.1	16.1 ± 3.8	50.0 ± 7.5	131 ± 17
hrpII integrant	21.8 ± 4.5	14.8 ± 3.2	66.0 ± 8.8	148 ± 32
Δpfpnp 1	NDc	ND	42.5 ± 6.0	112 ± 15
Δpfpnp 2	ND	ND	47.3 ± 9.0	155 ± 13

^ap = 0.25.

^bp = 0.23.

^cND, not detectable.