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Infect. Immun., 06 1995, 2120-2125, Vol 63, No. 6
F Salas, J Fichmann, GK Lee, MD Scott and PJ Rosenthal
Erythrocytic malaria parasites degrade hemoglobin as a principal source of
amino acids for parasite protein synthesis. We have previously shown that a
Plasmodium falciparum trophozoite cysteine proteinase, now termed
falcipain, is required for hemoglobin degradation, and we have hypothesized
that this proteinase is responsible for initial cleavages of hemoglobin. To
further evaluate the biological role of falcipain, we expressed the enzyme
in bacterial and viral expression systems. After expression in the
baculovirus system, falcipain was enzymatically active and had biochemical
properties very similar to those of the native proteinase. Recombinant
falcipain rapidly hydrolyzed both denatured and native hemoglobin.
Hemoglobin hydrolysis was blocked by cysteine proteinase inhibitors but not
by inhibitors of other classes of proteinases. Our results support our
hypothesis that falcipain is a critical malarial hemoglobinase that is
responsible for both initial cleavages of hemoglobin and the subsequent
hydrolysis of globin into small peptides.
Copyright © 1995, American Society for Microbiology
Functional expression of falcipain, a Plasmodium falciparum cysteine proteinase, supports its role as a malarial hemoglobinase
Department of Medicine, San Francisco General Hospital, University of California 94143, USA.
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