Plasmodium Falciparum: Chymotryptic-Like Proteolysis Associated with a 101-kDa Acidic-Base Repeat Antigen
Abstract
Malaria proteinases appear to function in the release of merozoites from infected erythrocytes and the invasion of merozoites into erythrocytes. Chymostatin, an inhibitor of chymotrypsin-like proteinases, inhibits malaria invasion and also inhibits apparent autoproteolysis of a 101-kDa acidic-basic repeat antigen (p101-ABRA) that is found in the vacuolar space surrounding merozoites in Plasmodium faiciparum-infected erythrocytes. After purification by a monoclonal antibody (MAb 3D5), p101-ABRA degrades into smaller fragments in the absence of chymostatin. In this study fluorogenic proteinase substrates of the type peptidyl-7-amino-4-trifluoromethyl coumarin with phenylalanine or tyrosine linked to AFC were used to characterize chymotryptic-like activity associated with p101-ABRA. When p101-ABRA from the cell extract of P. falciparum-schizont-infected erythrocytes was affinity purified on MAb 3D5 beads, chymotryptic-like activity bound to the beads. Seventy-four percent to 96% of the activity detected using MeOSuc-KLF-AFC, Suc-LLVY-AFC, or SY-AFC at a pH optimum of 7.0 was removed from the extract and 6 to 33% was detected on the washed beads. Attempts to recover active enzyme eluted from the beads were not successful. Enzymes cleaving two other substrates (MeOSuc-AAPM-AFC and F-AFC) did not significantly bind to mAB 3D5 beads. Chymotryptic-like activity was also associated with p101-ABRA in fractions from sequential DEAE-Sephacel chromatography, Sephacryl S-200 chromatography, and nondenaturing polyacrylamide gel electrophoresis....Malaria, Plasmodium falciparum, Antigens, Acidic-Basic Repeat Antigens(ABRA), Protease, Proteolysis, Vaccine development, Merozoite surface antigen, Protease purification and detection methods.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1992
- Accession Number
- ADA260199
Entities
People
- J. D. Haynes
- Jeffrey D. Chulay
- Mark Nwagwu
- Palmer A. Orlandi
Organizations
- Walter Reed Army Institute of Research