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CuZn superoxide dismutase activities from Fasciola hepatica

Published online by Cambridge University Press:  01 December 1998

L. PIACENZA
Affiliation:
Unidad de Biología Parasitaria, Facultad de Ciencias, Instituto de Higiene, Av. A. Navarro 3051 CP11600, Montevideo, Uruguay
R. RADI
Affiliation:
Departamento de Bioquímica, Facultad de Medicina, Gral Flores 2125 CP11800, Montevideo, Uruguay
F. GOÑI
Affiliation:
Departamento de Immunología, Facultad de Química, Instituto de Higiene Av. A. Navarro 3051 CP11600, Montevideo, Uruguay
C. CARMONA
Affiliation:
Unidad de Biología Parasitaria, Facultad de Ciencias, Instituto de Higiene, Av. A. Navarro 3051 CP11600, Montevideo, Uruguay

Abstract

The levels of superoxide dismutase (SOD) were determined in detergent-soluble, somatic and excretion–secretion (E–S) preparations from adult Fasciola hepatica using the xanthine oxidase system and visualized in substrate gels. Compared to detergent-soluble and somatic extracts, E–S products showed the highest SOD activity (88 ·5 U/mg), indicating active release to the medium in which parasites were maintained. SOD specific activity was also detected at high levels in E–S products from 3-week-old and 5-week-old immature migrating flukes (25 and 143 U/mg, respectively). In all preparations except for the somatic extract, the activity was characterized as cyanide-sensitive CuZn SOD. Differences in SOD isoenzyme profiles between the extracts were observed in native polyacrylamide gel electrophoresis: the somatic and detergent-soluble extracts exhibited 1 band of activity while the E–S products from immature and adults flukes contained 2 and 3 migrating bands, respectively. SOD was purified from the detergent-soluble extract and E–S products of adult worms by a combination of ultrafiltration, gel filtration on Sephacryl S-200 HR and ion-exchange chromatography on QAE Sephadex A-50. The SOD from detergent-soluble extract showed, by SDS–PAGE analysis, 1 band of 16 kDa apparent molecular weight. The SOD from E–S products showed 2 bands of 16 and 60 kDa apparent molecular weight. N-terminal sequence analysis of the 16 kDa band from the detergent-soluble preparation showed some similarity with Schistosoma mansoni cytoplasmic SOD. These enzymes may have a potential role in the evasion of the oxidative burst killing mechanism by immune cells.

Type
Research Article
Copyright
1998 Cambridge University Press

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