From the Guidelines
Ubiquinone plays a fundamental role in mitochondrial bioenergetics as an electron and proton carrier, facilitating cellular energy production in the electron transport chain. According to the espen micronutrient guideline 1, ubiquinone, also known as CoQ10, is a fat-soluble compound that serves as a mobile electron carrier in the electron transport chain. Its primary function is to shuttle electrons between complex I or II to complex III, facilitating cellular energy (ATP) production.
Key Functions of Ubiquinone
- Electron and proton carrier in the electron transport chain
- Facilitates cellular energy (ATP) production
- Crucial in tissues with high energy requirements, such as the heart, skeletal muscles, kidneys, liver, and brain
- Also acts as an antioxidant, protecting cellular membranes against the toxic effects of free radicals As noted in the guideline 1, CoQ10 is essential for the health of all tissues and organs, and its endogenous biosynthesis tends to decline with age.
Clinical Implications
- Ubiquinone's role in the electron transport chain highlights the importance of mobile electron carriers in energy production within cells
- Disruption of the electron transport chain due to ubiquinone deficiency can lead to decreased ATP production and potentially cause mitochondrial dysfunction
- The guideline 1 emphasizes the importance of CoQ10 in maintaining cellular energy production and overall tissue health.
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.