HIGH-LEVEL EXPRESSION AND CHARACTERIZATION OF PLASMEPSIN II, AN ASPARTIC PROTEINASE FROM PLASMODIUM-FALCIPARUM

DNA encoding the last 48 residues of the propart and the whole mature sequence of Plasmepsin II was inserted into the T7 dependent vector pE T 3a for expression in E. coli. The resultant product was insoluble bu t accumulated at similar to 20 mg/l of cell culture. Following solubil isation with urea, the zymogen was refolded and, after purification by ion-exchange chromatography, was autoactivated to generate mature Pla smepsin II. The ability of this enzyme to hydrolyse several chromogeni c peptide substrates was examined; despite an overall identity of simi lar to 35% to human renin, Plasmepsin II was not inhibited significant ly by renin inhibitors.