title: Self-proteolysis of the cysteine proteinase, cruzipain, from Trypanosoma cruzi gives a major fragment corresponding to its carboxy-terminal domain.
abstract: The major cysteine proteinase (cruzipain) purified from Trypanosoma cruzi epimastigotes catalyzes its own degradation in the presence of beta-mercaptoethanol, at 56 degrees C and pH 6. The reaction is affected by the same inhibitors which inhibit the azocaseinase activity, and yields a major 25-kDa fragment, which contains carbohydrate, few, if any, aromatic amino acids, and presents a proline-rich N-terminus (GPGPXPEP...), in addition to a number of small peptides, which can be isolated by reversed-phase HPLC, but are lost during electrophoresis. The results, together with recently published evidence of Mottram et al. and Eakin et al., are compatible with a structure for cruzipain consisting of a conventional cysteine proteinase moiety, linked to a long C-terminal extension including the 25-kDa fragment, which would contain a high proportion of the carbohydrate and the proline residues present in the original 60-kDa molecule.
authors.affiliation: Ludwig Institute for Cancer Research, Uppsala Branch, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Hellman
authors.forename: C
authors.initials: C
authors.lastname: Wernstedt
authors.forename: J J
authors.initials: JJ
authors.lastname: Cazzulo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003546:Cysteine Endopeptidases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008623:Mercaptoethanol / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D015800:Protozoan Proteins; D012689:Sequence Homology, Nucleic Acid; D014346:Trypanosoma brucei brucei / Q000201:enzymology; D014349:Trypanosoma cruzi / Q000201:enzymology*; D014357:Trypsin
chemical_list: D002241:Carbohydrates; D010446:Peptide Fragments; D015800:Protozoan Proteins; D008623:Mercaptoethanol; D014357:Trypsin; D003546:Cysteine Endopeptidases; C063214:cruzipain