Detection and characterization of a selective endopeptidase from Plasmodium berghei by using fluorogenic peptidyl substrates.

By using fluorogenic peptidyl-3-amino-9-ethyl-carbazole a highly selective endopeptidase for the Val-Leu-Gly-Arg sequence was demonstrated in endoerythrocytic stages of Plasmodium berghei. Val-Leu-Gly-Arg-endopeptidase showed a maximum activity in pH range 7.0-8.0; it was completely inhibited by 1 mM leupeptin and 1 mM antipain. A complete inhibition was also obtained by 15 mM chloroquine. This trypsin-like activity was negligible in uninfected red blood cells. The high sensitive fluorogenic procedure could be performed on cell fractions, cell lysates as well as supernatants.