期刊
JOURNAL OF PHYSICAL CHEMISTRY B
卷 118, 期 41, 页码 11863-11872出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp504518g
关键词
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资金
- FAPESP (Fundacao de Amparo a Pesquisa do Estado de sao Paulo) [2012/07456-7, 2012/50680-5, 2012/12663-1]
- CNPq (Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico)
- CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)
- UFABC/Nucleo de Bioquimica e Biotecnologia (NBB)
- Central Experimental Multiusuarios (CEM)
- PRONEX/FINEP (Programa de Apoio aos Nucleos de Excelencia)
- PRPUSP (Pro-Reitoria de Pesquisa da Universidade de Sao Paulo)
- Instituto do Milenio-Redoxoma [420011/2005-6]
- INCT Redoxoma (FAPESP/CNPq/CAPES) [573530/2008-4]
- NAP Redoxoma (PRPUSP) [2011.1.9352.1.8]
- CEPID Redoxoma (FAPESP) [2013/07937-8]
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [12/50680-5] Funding Source: FAPESP
Fluorescence quenching of lipid-bound pyrene was used to assess the binding of cytochrome c (cyt c) to liposomes that mimic the inner mitochondrial membrane (IMM) POPC/DOPE/TOCL, with the conditions that it did or did not contain oxidized phosphatidylcholine molecules, i.e., 1-O-hexadecyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC), or a mixture of two hydroperoxide isomers derived from POPC (POPCOX). The binding isotherms reveal two dissociation constants, KD(1) and KD(2), representing, respectively, the low- and high-affinity states of the membrane. These dissociation constants probably are due to the lipid reorganization promoted by cyt c, as observed in giant unilamellar vesicles that contain fluorescent cardiolipin (CL). The presence of PazePC, which has a nonreactive carboxylic group, increased the KD(1) and KD(2) values 1.2- and 4.5-fold, respectively. The presence of POPCOX which has a reactive peroxide group, decreased the KD(1) value 1.5-fold, increased the KD(2) value 10-fold, and significantly reduced the salt-induced detachment of cyt c. MALDI-TOF spectrometry analysis of cyt c incubated with liposomes containing POPCox demonstrated a mass increase corresponding to the formation of nonenal adducts as hydrophobic anchors. Electronic absorption spectroscopy, circular dichroism, and magnetic circular dichroism demonstrated that all of the lipids studied promoted changes in the cyt c coordination sphere. Therefore, in the presence of CL, the oxidation of zwitterionic lipids also promotes changes in the cyt c structure and in the affinity for lipid bilayers.
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