Biological membranes can be protected from lipid peroxidation by antioxidant enzymes including catalase (CAT) and @entity4259 -dependent @entity2041 peroxidases 1 and 4 (GPx1 and @entity70518 ). Unlike GPx1, @entity70518 can directly detoxify lipid @entity8415 in membranes without prior action of phospholipase A(2). We hypothesized that (1) @entity70518 is enhanced in species that contain elevated levels of highly oxidizable @entity1474 ( @entity5204 ) and (2) activities of antioxidant enzymes are prioritized to meet species-specific oxidative stresses. In this study we examined (i) activities of the oxidative enzyme @entity1792 synthase (CS) and antioxidant (CAT, GPx1 and @entity70518 ) enzymes, (ii) @entity70518 protein expression, and (iii) phospholipid composition in livers of five species of marine fish ( @entity14994 , @entity26962 , @entity8575 , @entity22159 and Myoxocephalus octodecemspinosus) that contain a range of @entity5204 . @entity70518 activity was, on average, 5.8 times higher in @entity22159 and @entity8575 than in the other three marine fish species sampled. Similarly, activities of CAT and GPx1 were highest in @entity8575 and @entity22159 , respectively. @entity70518 activity for all species correlates with membrane unsaturation, as well as oxidative activity as indicated by CS. These data support our hypothesis that @entity70518 level in marine fish is a function, at least in part, of high @entity5204 content in these animals. GPx1 activity was also correlated with membrane unsaturation, indicating that marine species partition resources among @entity2041 -dependent defenses for protection from the initial oxidative insult (e.g. @entity274 ) and to repair damaged lipids within biological membranes.

Relationship between oxidizable fatty acid content and level of antioxidant XXXX peroxidases in marine fish.

@entity8415 :: ('CHEBI:35924', 'Chemical') :: ['hydroperoxides'] @entity5204 :: ('CHEBI:26208', 'Chemical') :: ['PUFA'] @entity22159 :: ('8078', 'Species') :: ['Fundulus heteroclitus', 'F. heteroclitus'] @entity274 :: ('CHEBI:16240', 'Chemical') :: ['H(2)O(2)'] @entity1792 :: ('MESH:D019343', 'Chemical') :: ['citrate'] @entity4259 :: ('MESH:D012643', 'Chemical') :: ['selenium'] @entity8575 :: ('7797', 'Species') :: ['Squalus acanthias', 'S. acanthias'] @entity14994 :: ('7769', 'Species') :: ['Myxine glutinosa'] @entity2041 :: ('MESH:D005978', 'Chemical') :: ['glutathione'] @entity1474 :: ('MESH:D005231', 'Chemical') :: ['polyunsaturated fatty acids'] @entity26962 :: ('7757', 'Species') :: ['Petromyzon marinus'] @entity70518 :: ('105932462', 'Gene') :: ['GPx4']
@entity2041 :: (MESH:D005978,Chemical) :: ['glutathione']
