Figure 7.

pH profiles of PfM1AAP and soluble extracts of malaria parasites. Recombinant PfM1AAP enzyme (1 μg) (A) or soluble extract of malaria parasites (5 μg) (B) was incubated in a series of pH-controlled buffers (0.1 M sodium acetate pH 5.0–5.5, 0.1 M sodium citrate pH 5.5–6.0, 0.1 M sodium phosphate pH 6.0–8.0, 0.1 M Tris buffer pH 7.5–8.5) in the presence of the fluorogenic peptide substrates H-Ala-NHMec, H-Leu-NHMec or H-Arg-NHMec. The release of the fluorophore NHMec was monitored in a fluorimeter with excitation at 360 nm and emission at 460 nm. Reaction rates were used to plot pH-activity curves.