Mitochondrial electron transport chain complexes and reactive oxygen species pools (ETC/ROS)

The mitochondrial electron transport chain (ETC) is a series of multi-subunit protein complexes (Complexes I-IV) and electron carriers located in the inner mitochondrial membrane that facilitate oxidative phosphorylation [1]. Its primary biological function is to transfer electrons from NADH and FADH2 to molecular oxygen, creating a proton gradient that drives ATP synthesis via ATP synthase [1]. During this process, reactive oxygen species (ROS) such as superoxide are generated as natural byproducts of electron leakage, primarily at Complexes I and III [2]. While low levels of ROS function in cellular signaling, excessive ROS production leads to oxidative stress, damaging lipids, proteins, and DNA, which is a hallmark of neurodegenerative diseases, cardiovascular disorders, and aging [2]. Pharmacological intervention targets this system in two main ways: by inhibiting specific complexes to modulate metabolism (e.g., metformin inhibiting Complex I for type 2 diabetes or cancer) or by using mitochondria-targeted antioxidants (e.g., MitoQ) to neutralize ROS pools [3, 4]. However, targeting the ETC carries significant safety risks, including the potential for systemic toxicity or lactic acidosis due to the impairment of essential cellular respiration [3, 8].

Other names

Mitochondrial respiratory chainOxidative phosphorylation systemOXPHOSMitochondrial redox system

Inhibition of electron transport through specific complexes (e.g., Complex I or III) to alter metabolic flux or scavenging of mitochondrial reactive oxygen species to prevent oxidative damage [3, 4, 5].