Polyethylene glycol promotes autoxidation of cytochrome c
Abstract
Cytochrome c (Cyt c) was rapidly oxidized by molecular oxygen in the presence, but not absence of PEG. The redox potential of heme c was determined by the potentiometric titration to be +236 ± 3 mV in the absence of PEG, which was negatively shifted to +200 ± 4 mV in the presence of PEG. The underlying the rapid oxidation was explored by examining the structural changes in Cyt c in the presence of PEG using UV–visible absorption, circular dichroism, resonance Raman, and fluorescence spectroscopies. These spectroscopic analyses suggested that heme oxidation was induced by a modest tertiary structural change accompanied by a slight shift in the heme position (<1.0 Å) rather than by partial denaturation, as is observed in the presence of cardiolipin. The near-infrared spectra showed that PEG induced dehydration from Cyt c, which triggered heme displacement. The primary dehydration site was estimated to be around surface-exposed hydrophobic residues near the heme center: Ile81 and Val83. These findings and our previous studies, which showed that hydrated water molecules around Ile81 and Val83 are expelled when Cyt c forms a complex with CcO, proposed that dehydration of these residues is functionally significant to electron transfer from Cyt c to CcO.
Journal
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- Biochimica et Biophysica Acta (BBA) - General Subjects
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Biochimica et Biophysica Acta (BBA) - General Subjects 1862 (6), 1339-1349, 2018-06
Elsevier
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Keywords
Details 詳細情報について
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- CRID
- 1050001339057636864
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- NII Article ID
- 120006585774
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- HANDLE
- 2115/72937
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- ISSN
- 03044165
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- Text Lang
- en
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- Article Type
- journal article
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- Data Source
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- IRDB
- Crossref
- CiNii Articles
- KAKEN