通过细胞染色体c氧化酶进行质子转位
M I Verkhovsky1, A Jasaitis, M L Verkhovskaya
1Helsinki Bioenergetics Group, Department of Medical Chemistry, Institute of Biomedical Sciences and Biocentrum Helsinki, University of Helsinki, Finland.
Nature
|August 10, 1999
概括
细胞染色体c氧化酶配对氧气减少到水与质子. 这项研究揭示了质子转位发生在氧化和还原阶段,挑战了以前的假设.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 生物能源学 生物能源学
背景情况:
- 细胞染色体c氧化酶对于细胞呼吸至关重要,催化氧气减少到水和质子转移.
- 质子转移与酶的催化循环的能量合,特别是氧化相对还原相,仍在争论中.
研究的目的:
- 为了研究纯化细胞染色体c氧化酶的催化循环期间的质子转位的时间和能量合.
- 解决关于质子是否仅与氧化阶段相关的争议.
主要方法:
- 时间解析的膜电位测量,使用纯化氧化酶复制成脂质体.
- 同时测量pH值以追踪质子转位事件.
主要成果:
- 质子电荷转移的一半发生在还原阶段,在氧化阶段之后.
- 在还原过程中,质子转位取决于氧化阶段立即先行.
- 在O2的酶氧化过程中,对质子转位的能量被保存.
结论:
- 通过细胞染色体c氧化酶的质子转位发生在其催化循环的氧化和还原阶段.
- 该酶在氧化过程中保存能量,其中一半用于氧化过程中的质子送,另一半在再减少过程中解锁.
相关概念视频
Electron Transport Chains
The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The electron transport chain is a set of proteins found in the inner mitochondrial membrane in eukaryotic cells. Its primary function is to establish a proton gradient that can be used during chemiosmosis to produce ATP and generate electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle.
The ETC is comprised of...
The ETC is comprised of...
Chemiosmosis
Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives many cellular processes. Oxidative phosphorylation involves two processes— the electron transport chain and chemiosmosis.
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
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Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Energy to Drive Translocation
Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
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Electron Transport Chain Components
The electron transport chain (ETC) is a crucial metabolic pathway that facilitates energy conversion in prokaryotic and eukaryotic cells. In eukaryotes, the ETC comprises four membrane-associated protein complexes in the inner mitochondrial membrane. In prokaryotes, the ETC in the plasma membrane can vary in composition, with fewer or different complexes depending on the organism and environmental conditions. These complexes transfer electrons from electron donors, such as NADH and FADH2, to...
Chemiosmosis and ATP Synthesis
The electron transport chain is a critical component of cellular respiration, occurring in the inner mitochondrial membrane. It facilitates the transfer of high-energy electrons from reduced cofactors NADH and FADH₂ to molecular oxygen, the final electron acceptor. This transfer of electrons through a series of protein complexes is tightly coupled to the translocation of protons across the membrane, generating a proton gradient essential for ATP synthesis.Electron Flow and Proton...


