Plasmodium falciparum: biochemical characterization of the cysteine protease falcipain-2'.
The Plasmodium falciparum cysteine proteases falcipain-2 and falcipain-3 are hemoglobinases and potential antimalarial drug targets. The falcipain-2' gene was identified recently and is nearly identical in sequence to falcipain-2. The product of this gene has not been studied previously. The mature protease domain of falcipain-2' was expressed in Escherichia coli, purified, and refolded to active enzyme. Functional analysis revealed similar biochemical properties to those of falcipain-2, including pH optima (pH 5.5-7.0), reducing requirements, and substrate preference. Studies with cysteine protease inhibitors showed similar inhibition of falcipain-2 and falcipain-2', although specificities were not identical. Considering activity against the presumed biological substrate, both enzymes readily hydrolyzed hemoglobin. Our results confirm that falcipain-2' is an active hemoglobinase and suggest that falcipain-2 and falcipain-2' play similar roles in erythrocytic parasites but that, for promising cysteine protease inhibitors, it will be important to confirm activity against this additional target.
Singh
Naresh
N
Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143-0811, USA.
Sijwali
Puran S
PS
Pandey
Kailash C
KC
Rosenthal
Philip J
PJ
D000595:Amino Acid Sequence; D000818:Animals; D003546:Cysteine Endopeptidases / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D015971:Gene Expression Regulation, Enzymologic; D006454:Hemoglobins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
D015853:Cysteine Proteinase Inhibitors; D006454:Hemoglobins; D003546:Cysteine Endopeptidases; C416224:falcipain 2