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Type: Artigo de periódico
Title: Liposome effect on the cytochrome c-catalyzed peroxidation of carbonyl substrates to triplet species
Author: Nantes, IL
Faljoni-Alario, A
Vercesi, AE
Santos, KE
Bechara, EJH
Abstract: Cytochrome c exhibits peroxidase activity on diphenylacetaldehyde (DPAA) and 3-methylacetoacetone (MAA), which is greatly affected by the presence and nature of charged liposome or micelle interfaces interacting with the enzyme. The ferricytochrome c reaction with DPAA is accelerated when the enzyme is attached to negatively charged interfaces. Whatever the medium, bulk solution or negatively charged dicetylphosphate (DCP), phosphatidyl coline/phosphatidylethanolamine/cardiolipin (PC/PE/CL) liposomes, this chemiluminescent reaction is accompanied by reduction of cytochrome c to its ferrous form. In turn, MAA is oxidized by cytochrome c exclusively when bound to DCP liposomes. Contrary to DPAA oxidation, the MAA reaction is followed by bleaching of cytochrome c, reflecting damage to the hemeprotein chromophore. The cytochrome-c-catalyzed oxidation of either DPAA or MAA leads to concomitant disappearance of the enzyme charge transfer absorption band at 695 nm. This suggests that the peroxidase activity of cytochrome c involves substrate-induced loss of the methionine ligand at the iron sixth coordination position, which is favored by interaction of cytochrome c with negatively charged interfaces. Accordingly, a decrease and blue shift of the charge transfer band could be observed in cytochrome-c-containing negatively charged DCP, PC/PE/CL liposomes or lysophosphatidylethanolamine micelles in the presence of DPAA or MAA.
Subject: cytochrome c
aldehyde and beta-diketone peroxidation
triplet biacetyl
triplet benzophenone
free radicals
Country: Inglaterra
Editor: Pergamon-elsevier Science Ltd
Rights: fechado
Identifier DOI: 10.1016/S0891-5849(98)00082-3
Date Issue: 1998
Appears in Collections:Unicamp - Artigos e Outros Documentos

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