Schistosoma mansoni and Fasciola hepatica are parasitic trematodes which contain cytochrome c peroxidase (CcP) in their mitochondria, an enzyme that is absent in mammalian tissues. CcP reduces hydrogen peroxide to H2O using cytochrome c as the electron donor. Both parasites are catalase deficient; thus, cytochrome c peroxidase and glutathione peroxidase are the enzymes involved in the detoxification of H2O 2 in these organisms. The enzymatic activity of these two peroxidases may enable S. mansoni and F. hepatica to survive oxidative stress. The main objective of this study was to characterize cytochrome c peroxidase from S. mansoni and F. hepatica . Kinetic studies of this enzyme in crude homogenate and isolated mitochondria of S. mansoni were initially performed, followed by purification studies from S. mansoni and F. hepatica . The parasite enzyme has affinity for horse heart and yeast cytochrome c and it is inhibited by sodium azide and potassium cyanide. CcP was purified close to homogeneity and identified as a protein containing heme. The antioxidant capability of F. hepatica CcP was tested in vitro , demonstrating that CcP protected the sugar deoxyribose from oxidative degradation. Exposure of adult worms to H2O2 caused a decrease in S. mansoni CcP activity in vivo. An attempt was made to clone the S. mansoni CcP gene. The experiments did not result in the cloning of the CcP gene, but led to the identification and cloning of another protein, a component of a cytosolic chaperonin, t-complex polypeptide one (TCP-1). TCP-1 from S. mansoni is highly homologous to TCP-1 proteins from different organisms including, Chinese hamster, human, Drosophila and yeast and carries ATP binding amino acid motifs indicating that it has ATPase activity.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.37700 |
| Date | January 1996 |
| Creators | Campos, Elida Geralda. |
| Contributors | Prichard, R. K. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Institute of Parasitology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001809641, proquestno: NQ70179, Theses scanned by UMI/ProQuest. |
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