The Hierarchy of Structural Transitions Induced in Cytochrome c by Anionic Phospholipids Determines Its Peroxidase Activation and Selective Peroxidation during Apoptosis in Cells

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• 作者：Alexander A. Kapralov ; Igor V. Kurnikov ; Irina I. Vlasova ; Natalia A. Belikova ; Vladimir A. Tyurin ; Liana V. Basova ; Quing Zhao ; Yulia Y. Tyurina ; Jianfei Jiang ; Hulya Bayir ; Yuri A. Vladimirov ; Valeri
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：December 11, 2007
• 年：2007
• 卷：46
• 期：49
• 页码：14232 - 14244
• 全文大小：474K
• 年卷期：v.46,no.49(December 11, 2007)
• ISSN：1520-4995

文摘

Activation of peroxidase catalytic function of cytochrome c (cyt c) by anionic lipids is associatedwith destabilization of its tertiary structure. We studied effects of several anionic phospholipids on theprotein structure by monitoring (1) Trp₅₉ fluorescence, (2) Fe-S(Met₈₀) absorbance at 695 nm, and (3)EPR of heme nitrosylation. Peroxidase activity was probed using several substrates and protein-derivedradicals. Peroxidase activation of cyt c did not require complete protein unfolding or breakage of theFe-S(Met₈₀) bond. The activation energy of cyt c peroxidase changed in parallel with stability energiesof structural regions of the protein probed spectroscopically. Cardiolipin (CL) and phosphatidic acid (PA)were most effective in inducing cyt c peroxidase activity. Phosphatidylserine (PS) and phosphatidylinositolbisphosphate (PIP₂) displayed a significant but much weaker capacity to destabilize the protein andinduce peroxidase activity. Phosphatidylinositol trisphosphate (PIP₃) appeared to be a stronger inducer ofcyt c structural changes than PIP₂, indicating a role for the negatively charged extra phosphate group.Comparison of cyt c-deficient HeLa cells and mouse embryonic cells with those expressing a fullcomplement of cyt c demonstrated the involvement of cyt c peroxidase activity in selective catalysis ofperoxidation of CL, PS, and PI, which corresponded to the potency of these lipids in inducing cyt c'sstructural destabilization.