title: A selenium-containing phospholipid-hydroperoxide glutathione peroxidase in Schistosoma mansoni.
abstract: The 100000Xg supernatant parasite platyhelminth Schistosoma mansoni exhibits a glutathione peroxidase activity with the substrate phosphatidylcholine hydroperoxide. Purification yielded a protein of 20 kDa molecular mass both on gel filtration column chromatography and SDS/PAGE, thus suggesting that S. mansoni expresses a protein similar to the mammalian selenoenzynic phospholipid-hydroperoxide glutathione peroxidase. Kinetic analysis and substrate specificity corroborated this assumption, the second-order rate constants for the oxidation of the ground-state enzyme (k+1) being higher with phosphatidylcholine hydroperoxide than with other peroxide substrates, such as cumene liydroperoxide or H2O2, and quantitatively similar to those of mammalian phospholipid-hydroperoxide glutathione peroxidase. Partial sequencing of the protein and selenium measurement by neutron activation analysis established that the purified peroxidase corresponded to the product of the S. mansoni gene previously reported and supposed to encode a selenium-containing glutathione peroxidase [Roche, C., Williams, D. L., Khalife, J., LePresle, T., Capron, A. & Pierce, R. J. (1994) Cloning and characterization of gene encoding Schistosoma mansoni glutathione peroxidase, Gene 138, 149 - 152]. S. mansoni thus contains a scienoperoxidase sharing molecular mass, catalytic efficiency and substrate specificity with phospholipid-hydroperoxide glutathione peroxidase, dismantling the concept that those enzymes are unique to vertebrate organisms.
authors.affiliation: Dipartimento di Chimica Biologica, Università di Padova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Maiorino
authors.forename: C
authors.initials: C
authors.lastname: Roche
authors.forename: M
authors.initials: M
authors.lastname: Kiess
authors.forename: K
authors.initials: K
authors.lastname: Koenig
authors.forename: D
authors.initials: D
authors.lastname: Gawlik
authors.forename: M
authors.initials: M
authors.lastname: Matthes
authors.forename: E
authors.initials: E
authors.lastname: Naldini
authors.forename: R
authors.initials: R
authors.lastname: Pierce
authors.forename: L
authors.initials: L
authors.lastname: Flohé
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D017238:Genes, Helminth; D005979:Glutathione Peroxidase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D012550:Schistosoma mansoni / Q000737:chemistry / Q000201:enzymology*; D012643:Selenium / Q000032:analysis / Q000737:chemistry; D013379:Substrate Specificity
chemical_list: D010446:Peptide Fragments; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D012643:Selenium