Electron transport chain

The electron transport chain (ETC) is a crucial process in cellular metabolism that involves the transfer of electrons from high-energy molecules to oxygen, resulting in the production of ATP and the generation of reactive oxygen species (ROS).

The mammalian mitochondrial ETC includes complexes I-IV, as well as the electron transporters ubiquinone and cytochrome c 2. However, the conventional view that high metabolic rate leads to increased ROS production is disputed, as 98-99% of ROS are generated during reverse electron flow, which occurs when there is a block at one or more of the ETC complexes 3. This leads to a buildup of electrons and thus ROS generation.

The ETC can be bypassed or impaired by various factors, including the presence of unsaturated fatty acids, which can inhibit oxidative metabolism and lead to mitochondrial dysfunction 7. Inhibiting the ETC, specifically complex I, can also reliably cause bipolar disorder in animal models 8. Furthermore, reductive stress, caused by the leakage of excess electrons through the inner membrane, can drive pathogenesis and progression of infectious diseases, such as tuberculosis 6.

Methylene blue, an electron acceptor, can help restore electron flow along the ETC in case of damage and speed it up even more when the ETC is functioning well 4. This highlights the importance of maintaining proper electron flow through the ETC for optimal cellular function.

In summary, the electron transport chain is a critical process in cellular metabolism that can be impaired by various factors, leading to the generation of ROS and mitochondrial dysfunction.