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Active site specificity of plasmepsin II
Author(s) -
Westling Jennifer,
Cipullo Patty,
Hung SuHwi,
Saft Howard,
Dame John B.,
Dunn Ben M.
Publication year - 1999
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.8.10.2001
Subject(s) - chemistry
Members of the aspartic proteinase family of enzymes have very similar three‐dimensional structures and catalytic mechanisms. Each, however, has unique substrate specificity. These distinctions arise from variations in amino acid residues that line the active site subsites and interact with the side chains of the amino acids of the peptides that bind to the active site. To understand the unique binding preferences of plasmepsin II, an enzyme of the aspartic proteinase class from the malaria parasite, Plasmodium falciparum , chromogenic octapeptides having systematic substitutions at various positions in the sequence were analyzed. This enabled the design of new, improved substrates for this enzyme (Lys‐Pro‐Ile‐Leu‐Phe*Nph‐Ala/Glu‐Leu‐Lys, where * indicates the cleavage point). Additionally, the crystal structure of plasmepsin II was analyzed to explain the binding characteristics. Specific amino acids (Met13, Ser77, and Ile287) that were suspected of contributing to active site binding and specificity were chosen for site‐directed mutagenesis experiments. The Met13Glu and Ile287Glu single mutants and the Met13Glu/Ile287Glu double mutant gain the ability to cleave substrates containing Lys residues.