Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30044 (antioxidant enzyme)
 8,037 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence suggests that the helminth antioxidant enzyme superoxide dismutase (SOD) may play a role in parasite's defense against the cellular immune mechanisms of the host. In order to investigate this for the human parasite Onchocerca volvulus, the enzyme activity was characterized, the release of SOD by the parasite was examined, and a complete cDNA encoding the O. volvulus SOD was identified. The SOD activity in adult O. volvulus was found to be 8.1 +/- 4.2 U/mg of protein. A Cu/Zn-containing enzyme was demonstrated by its sensitivity towards cyanide, azide, and hydrogen peroxide. Isoelectric focusing, combined with an enzyme activity assay, revealed two activities at pI 6.8 and 7.6, with both activities inhibited by KCN. Adult parasites, maintained in vitro, released SOD into the culture medium, which was detected by enzyme activity. In parallel, lactate production was measured to ensure the viability of the parasite. Oligonucleotides (based upon conserved sequences in the SOD genes of other organisms) and the polymerase chain reaction were used to identify a portion of the SOD gene from O. volvulus genomic DNA. A cDNA library was constructed in lambda unizapII and screened with the genomic polymerase chain reaction fragment. A complete cDNA encoding the Cu/Zn SOD was identified, and its nucleotide sequence was determined. Southern blot hybridization experiments indicated that the Cu/Zn SOD is encoded by a single-copy gene with at least one intron.
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PMID:Characterization and molecular cloning of a Cu/Zn superoxide dismutase from the human parasite Onchocerca volvulus. 203 66

Random screening of an Onchocerca volvulus third-stage (L3) cDNA library identified a highly abundant cDNA encoding a newly discovered antioxidant enzyme, thioredoxin peroxidase (TPx), a member of the peroxidoxin superfamily. This TPx cDNA (Ov-tpx-2) encodes a polypeptide of 199 amino acid residues with a calculated molecular weight of 21,890 Da. The Ov-tpx-2 cDNA represents roughly 2.5% of the total cDNAs from the L3 cDNA library. The gene was expressed in Escherichia coli and the protein product was shown to have antioxidant activity. Antiserum raised against Ov-TPX-2 recognized a native protein from extracts of both the L3 and adult-stages with a molecular weight of 22 kD. The localization and stage-specificity of Ov-TPX-2 protein was analyzed by immunocytochemistry and immunoelectron microscopy using monospecific antibodies. Expression was detected in late first-stage larvae during development in the vector and increased in intensity during differentiation to the infective L3-stage. The antigen was also detected in post-infective larvae and adult worms. In larvae, Ov-TPX-2 protein was predominantly localized to the hypodermis and cuticle, with additional sites in the hypodermal chords and multivesicular bodies. In adult worms, the primary sites of expression were the uterine epithelium and intestine, with additional labeling of the body wall and cuticle. Developing embryos and microfilariae in utero were bathed in Ov-TPX-2 protein discharged from epithelial cells. These results suggest that Ov-TPX-2 may protect the parasites from being damaged by host-generated oxidative stress and that Ov-TPX-2 protein provides the H2O2-detoxifying activity predicted but not previously identified in filarial parasites. Its highly upregulated expression in infective larvae may aid in parasite establishment following transmission to the definitive host.
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PMID:Thioredoxin peroxidase from Onchocerca volvulus: a major hydrogen peroxide detoxifying enzyme in filarial parasites. 956 16