title: Identification of peptides inhibitory to recombinant cysteine proteinase, CPB, of Leishmania mexicana.
abstract: We have identified peptides that are relatively resistant to hydrolysis by a recombinant cysteine proteinase, CPB2.8DeltaCTE, of Leishmania mexicana, and yet exhibit inhibition constant (K(i)) values in the nanomolar range. Common to these peptides is a basic-hydrophobic-hydrophobic motif in the P3-P1 sites, which is also present in the pro-region of the enzyme. A nine-amino acid stretch, FAARYLNGA, which has good homology to the pro-region of mammalian cathepsin L was identified as the part of the pro-region most likely to interact with the active site of the parasite enzyme. This peptide is not hydrolyzed by CPB2.8DeltaCTE and inhibited it with a K(i) of 4 microM. Extension of this sequence at both the N- and C-termini and the introduction of ortho-aminobenzoic acid at the N-terminal site reduced the K(i) value to 30 nM. The best substrate for CPB2.8DeltaCTE was also well hydrolyzed by cathepsin L, however the best inhibitor of the parasite enzyme inhibit poorly cathepsin L, with K(i) value two order of magnitude higher than against the parasite enzyme. These promising data provide insights into the peculiar specificity of the parasite enzyme and will aid the design of antiparasitic drugs directed against the leishmanial enzyme.
authors.affiliation: Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Tres de Maio 100, 04044-20, São Paulo, Brazil.
authors.forename: L C
authors.initials: LC
authors.lastname: Alves
authors.forename: P M
authors.initials: PM
authors.lastname: St  Hilaire
authors.forename: M
authors.initials: M
authors.lastname: Meldal
authors.forename: S J
authors.initials: SJ
authors.lastname: Sanderson
authors.forename: J C
authors.initials: JC
authors.lastname: Mottram
authors.forename: G H
authors.initials: GH
authors.lastname: Coombs
authors.forename: L
authors.initials: L
authors.lastname: Juliano
authors.forename: M A
authors.initials: MA
authors.lastname: Juliano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000235:genetics; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D007894:Leishmania mexicana / Q000201:enzymology*; D008322:Mammals; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D010446:Peptide Fragments; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L