Una peptidasa ácida, insensible a inhibidores clásicos, en extractos proteicos de Trypanosoma cruzi, proveniente de una zona rural de Venezuela, endémica para la enfermedad de Chagas / Description of an acidic peptidase, insensitive to classical inhibitors, in protein extracts of Trypanosoma cruzi, from a rural area of Venezuela, where Chagas disease is endemic

RESUMEN

Mediante dos métodos de ensayo de peptidasas, uno en fase líquida y otro en fase gel (zimografía en geles), se detectó una peptidasa, en extractos proteicos crudos de epimastigotes de Trypanosoma cruzi, provenientes de un área rural de Venezuela endémica para el mal de Chagas. La peptidasa mostró actividad en el intervalo de pH comprendido entre 2,0 y 2,9. Bajo las condiciones experimentales descritas, la peptidasa resultó insensible a concentraciones usuales de inhibidores clásicos de peptidasas de tipo serina, cisteína, metalo-peptidasas y aspártico. No obstante, a semejanza de la pepsina porcina a pH 2,9, la peptidasa es inhibida en presencia de 5mM DTT.

ABSTRACT

Through two peptidase assay methods, one in liquid-phase and another, in gel-phase (gel zymography), an acid peptidase was detected in protein crude extracts of epimastigotes of Trypanosoma cruzi, from a rural area of Venezuela where Chagas disease is endemic. The peptidase shows activity at a pH range between 2.0 and 2.9. Under the experimental conditions described, the acid peptidase was insensitive to usual concentrations of peptidase inhibitors of the types serine, cysteine, aspartic and metallo-peptidases. Nevertheless, like porcine pepsin at pH 2.9, the peptidase was inhibited in the presence of 5mM DTT.