Studies on Filarial Proteinases and Their Inhibitors for Development of Filarial Drugs

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1.Two aspartic proteinases were purified from the crude extract of boviae filarial parasites (Setcria digitata) collected in Sri Lanka by sucessive steps of chromatography on columns of DEAE-cellulose, Sephacryl S-200, pepstatia-Sepharose, and monoQ, and their enzymat.ic and molecular properties were investigated and the N-terminal sequences were determined. In addition, neutral proteinases were partially purified.2.cDNA libraries were prepared from the mRNAs of human filarial parasites, including Brugia malayi. Ozwhocerca volvulus and Brugia phangi, and genomic DNA libraries from Brugia malayi and Wuchereria bancrofti. Then, full-length cDNAs of two aspartic proteinases, Asp2 and Asp3. and a partial length cDNA of one aspartic proteinase, Aspl, were isolated from the cDNA libraries of Brugia malayi and their base sequences were determined and amin acid sequences deduced. A phylogenetic tree of aspartic proteinases includingAsp2 and Asp3 was constructed. indicating. that Asp2 somewhat … More resembles mammalian cathepsin D, whereas Asp3 is unique in that it is significantly diverged from both cathepsin D and pepsin. AspI was shown to be fairly similar in sequence to Asp2.3, From the cDNA library of Brugia malayi, full-length cDNAs of two cysteine proteinases, Cysl and Cys2, were isolated, and their base sequences were determined and amino acid sequences deduced. The sequences are fairly similar between Cys1 and Cys2, but are markedly different from those of mammalian cysteine proteinases.4.In addition, purification and/or characterization studies were performed for a novel inembrane-bound inetalloendopeptidase cleaving progastrin C-terminal (88-101) peptide from bovine brain, a porcine brain endopeptidase specific for the C-terminal CAAX motif of Ras and related proteins, porcine . enteropeptidase, pancreatic trypsin and alpha-chymotrypsin, a rat liver microsomal membrane- bound serine proteinase(hepsin), colopsin (a novel membrane-bound serine proteinase from intestine), human and mouse cathepsin E, coelacant pepsinogen, nope nthesin, mold acid proteinases A and B, bacterial metalloendopeptidases, sigaital peptidase and brotnelain inhibitors. Less