A panel of intramolecularly quenched fluorogenic substrates containing the conserved QVVA and LVG inhibitory sequences of cystatin inhibitors was used to describe the specificity of the major cysteine proteinase of Trypanosoma cruzi (cruzipain or cruzain). This approach was based on the observations that: (1) cruzipain is strongly inhibited by chicken cystatin and rat T-kininogen, two representative members of cystatin families 2 and 3; (2) the QVVA- and LVG-containing substrates are specifically hydrolysed by papain-like proteinases; and (3) the cystatin-like motifs are similar to the proteolytically sensitive sequences in cruzipain that separate the pro-region and/or the C-terminal extension from the catalytic domain. Specificity constants (kcat./Km) were determined and compared with those of mammalian cathepsins B and L from rat liver lysosomes. Cruzipain and the mammalian proteinases cleaved cystatin-derived substrates at the same site, but their specificities differed significantly. Increased specificity for cruzipain was obtained by replacing amino acids at critical positions on both sides of the cleavage sites, especially at position P2´. The specificity constants (kcat./Km) obtained for the two substrates with a prolyl residue at P2´ (O-aminobenzoyl-QVVAGP-ethylenediamine 2-4-dinitrophenyl and O-aminobenzoyl-VVGGP-ethylenediamine 2-4-dinitrophenyl) were about 50 times higher for cruzipain than for rat cathepsin L and about 100 times higher than for cathepsin B. Diazomethylketone derivatives, based on the non-prime sequence of cystatin-derived substrates, inhibited cruzipain irreversibly, but their inactivation rate constants were considerably lower than those for mammalian cathepsins B and L, confirming the importance of P´ residues for cruzipain specificity.
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Research Article|
February 01 1996
Investigation of the substrate specificity of cruzipain, the major cysteine proteinase of Trypanosoma cruzi, through the use of cystatin-derived substrates and inhibitors
Carole SERVEAU;
Carole SERVEAU
*Laboratory of Enzymology and Protein Chemistry, CNRS URA 1334, University François Rabelais, 2bis Bd Tonnellé, F37032 Tours Cedex, France
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Gilles LALMANACH;
Gilles LALMANACH
*Laboratory of Enzymology and Protein Chemistry, CNRS URA 1334, University François Rabelais, 2bis Bd Tonnellé, F37032 Tours Cedex, France
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Maria A. JULIANO;
Maria A. JULIANO
†Department of Biophysics, Escola Paulista de Medicina, Caixa Postal 20388, 04304 Sao Paulo, Brazil
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Julio SCHARFSTEIN;
Julio SCHARFSTEIN
‡Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21944 Rio de Janeiro, Brazil
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Luiz JULIANO;
Luiz JULIANO
†Department of Biophysics, Escola Paulista de Medicina, Caixa Postal 20388, 04304 Sao Paulo, Brazil
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Francis GAUTHIER
Francis GAUTHIER
§
*Laboratory of Enzymology and Protein Chemistry, CNRS URA 1334, University François Rabelais, 2bis Bd Tonnellé, F37032 Tours Cedex, France
§To whom correspondence should be addressed.
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Publisher: Portland Press Ltd
Received:
June 05 1995
Revision Received:
September 25 1995
Accepted:
October 04 1995
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 313 (3): 951–956.
Article history
Received:
June 05 1995
Revision Received:
September 25 1995
Accepted:
October 04 1995
Citation
Carole SERVEAU, Gilles LALMANACH, Maria A. JULIANO, Julio SCHARFSTEIN, Luiz JULIANO, Francis GAUTHIER; Investigation of the substrate specificity of cruzipain, the major cysteine proteinase of Trypanosoma cruzi, through the use of cystatin-derived substrates and inhibitors. Biochem J 1 February 1996; 313 (3): 951–956. doi: https://doi.org/10.1042/bj3130951
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