title: Kinetic analysis of plasmepsins I and II aspartic proteases of the Plasmodium falciparum digestive vacuole.
abstract: Plasmepsins I and II are Plasmodium falciparum aspartic proteases implicated in hemoglobin degradation. Using a synthetic fluorogenic peptide substrate based on the initial hemoglobin cleavage site, we have analyzed kinetic parameters of the two enzymes in native and recombinant forms. Both native plasmepsins cleave the model substrate well. Recombinant plasmepsin II behaves similarly to native enzyme, substantiating its usefulness for inhibition and structural studies. In contrast, recombinant plasmepsin I does not resemble its native homolog kinetically. A hybrid molecule, in which the polyproline loop of plasmepsin I has been replaced by the homologous sequence from plasmepsin II, still maintains the specificity/kinetics of plasmepsin II. This suggests that the polyproline loop, important for substrate recognition in the mammalian aspartic protease renin, does not play a similar role in the plasmepsins.
authors.affiliation: Howard Hughes Medical Institute, Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Luker
authors.forename: S E
authors.initials: SE
authors.lastname: Francis
authors.forename: I Y
authors.initials: IY
authors.lastname: Gluzman
authors.forename: D E
authors.initials: DE
authors.lastname: Goldberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism*; D002863:Chromogenic Compounds; D005456:Fluorescent Dyes; D005914:Globins / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D017421:Sequence Analysis; D014617:Vacuoles / Q000201:enzymology*
chemical_list: D002863:Chromogenic Compounds; D005456:Fluorescent Dyes; D006454:Hemoglobins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D005914:Globins; D016282:Aspartic Acid Endopeptidases; C089643:plasmepsin; C100637:plasmepsin II