From the Guidelines
Ubiquinone plays a crucial role in the electron transport chain as an electron and proton carrier, facilitating cellular energy production by shuttling electrons from complex I or II to complex III, as evident in the 2022 espen micronutrient guideline 1. The electron transport chain is a series of protein complexes located in the mitochondrial inner membrane, and ubiquinone, also known as coenzyme Q10, is a vital component of this process.
- Its primary function is to accept electrons from complex I and complex II, and then donate these electrons to complex III, thereby facilitating the generation of a proton gradient across the membrane.
- This proton gradient is essential for the production of ATP, which is the primary energy currency of the cell, as highlighted in the guideline 1.
- Ubiquinone's ability to cycle between its oxidized and reduced states makes it an essential component of the electron transport chain, allowing it to continuously shuttle electrons and protons, and ultimately enabling the cell to harness energy from nutrients through oxidative phosphorylation. Key aspects of ubiquinone's role in the electron transport chain include:
- Its lipid-soluble nature, which allows it to move freely within the phospholipid bilayer of the membrane, as noted in the guideline 1.
- Its ability to accept and donate electrons, which is critical for the generation of the proton gradient, and its role in protecting cellular membranes against the toxic effects of free radicals, as discussed in the 2022 study 1. Overall, ubiquinone's role in the electron transport chain is critical for maintaining the flow of electrons and protons, and ultimately enabling the cell to produce energy through oxidative phosphorylation, as emphasized in the espen micronutrient guideline 1.
From the Research
Role of Ubiquinone in the Electron Transport Chain
- Ubiquinone, also known as coenzyme Q, plays a crucial role in the mitochondrial electron transport chain (ETC) as an electron transporter 2.
- It is extremely hydrophobic and resides in membranes, allowing it to facilitate the transfer of electrons in the ETC 2.
- Ubiquinone is central to the entire redox balance of the cell and its structure and properties have remained unchanged from bacteria to vertebrates 2.
Mechanism of Action
- Ubiquinone carries electrons in the mammalian electron transport chain, preferentially delivering them to the terminal electron acceptor oxygen (O2) 3.
- In hypoxia, ubiquinol diverts these electrons onto fumarate instead, highlighting the flexibility of the ETC 3.
- The role of ubiquinone in complex I function exceeds that of a mere substrate or electron acceptor, and it may be the redox element coupling electron transfer to proton translocation 4.
Importance in Cellular Processes
- Ubiquinone is required for several crucial cellular processes, including the synthesis of adenosine triphosphate (ATP) and the regulation of reactive oxygen species production 5.
- Deficiencies in ubiquinone, either primary or secondary, can have significant biological consequences, including mitochondrial disorders and aging 2.
- Supplementation with ubiquinol, a reduced form of coenzyme Q10, may improve endothelial function in patients with heart failure with reduced ejection fraction 6.