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|Type:||Artigo de periódico|
|Title:||Leishmania infantum: Provision of reducing equivalents to the mitochondrial tryparedoxin/tryparedoxin peroxidase system|
|Abstract:||Within the mitochondrion of Leishmania infantum, hydroperoxide metabolism relies on the activity of tryparedoxin-dependent peroxidases (TXNPxs). Tryparedoxins (TXNs) are thioredoxin-related oxidoreductases, which in vitro are reduced by the trypanothione reductase/trypanothione [TR/T(SH)(2)] redox couple. Still, there is no evidence that this actually occurs in the mitochondrion. This communication addresses the question of how the mitochondrial TXN/TXNPx system is reduced. First, using a digitonin fractionation assay, we show that TR activity is absent from the L. infantum mitochondrion. The possibility that this organelle possesses alternative electron sources for TXN/TXNPx is then investigated. Biochemical assays performed with purified recombinant enzymes, revealed that TR and T(SH)(2) can be replaced, albeit less efficiently, by the dihydrolipoamide dehydrogenase/lipoamide redox system as TXN/TXNPx electron donor. This result challenges the classical view that T(SH)(2) is the only reductant for TXNs and add new prospects regarding the involvement of 2-oxo acid dehydrogenase complexes in L. infantum mitochondrial hydroperoxide metabolism. (C) 2008 Elsevier Inc. All rights reserved,|
Trypanosoma brucei, Trypanosoma cruzi, Leishmania spp., trypanosomatids
|Editor:||Academic Press Inc Elsevier Science|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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