Editing Coenzyme Q10 (section)

==Biological functions==
{{See also|Q cycle}}
CoQ<sub>10</sub> is a component of the mitochondrial [[electron transport chain]] (ETC), where it plays a role in oxidative phosphorylation, a process required for the biosynthesis of adenosine triphosphate, the primary energy source of cells.<ref name=lpi/><ref name="pmid34064686"/><ref name="pmid34596729">{{cite journal |vauthors=Pradhan N, Singh C, Singh A |title=Coenzyme Q10 a mitochondrial restorer for various brain disorders |journal=Naunyn Schmiedebergs Arch Pharmacol |volume=394 |issue=11 |pages=2197–2222 |date=November 2021 |pmid=34596729 |doi=10.1007/s00210-021-02161-8}}</ref>

CoQ<sub>10</sub> is a [[Lipophilicity|lipophilic]] molecule that is located in all biological membranes of human body and serves as a component for the synthesis of ATP and is a life-sustaining cofactor for the three complexes ([[complex I]], [[complex II]], and [[complex III]]) of the ETC in the mitochondria.<ref name=lpi/><ref name="Kadian-2022"/> CoQ<sub>10</sub> has a role in the transport of [[proton]]s across [[lysosome|lysosomal]] membranes to regulate pH in lysosome functions.<ref name=lpi/>

The mitochondrial oxidative phosphorylation process occurs in the inner mitochondrial membrane of eukaryotic cells.<ref name=lpi/> This membrane is highly folded into structures called cristae, which increase the surface area available for oxidative phosphorylation. CoQ<sub>10</sub> plays a role in this process as an essential cofactor of the ETC located in the inner mitochondrial membrane and serves the following functions:<ref name=lpi/><ref name="pmid34596729"/>
* electron transport in the mitochondrial ETC, by shuttling electrons from mitochondrial complexes like [[nicotinamide adenine dinucleotide]] (NADH), [[ubiquinone reductase]] (complex I), and succinate ubiquinone reductase (complex II), the fatty acids and branched-chain amino acids oxidation (through flavin-linked dehydrogenases) to [[Ubiquinol--cytochrome-c reductase|ubiquinol–cytochrome-c reductase]] (complex III) of the ETC:<ref name=lpi/><ref name="pmid34596729"/> CoQ<sub>10</sub> participates in fatty acid and glucose metabolism by transferring electrons generated from the reduction of fatty acids and glucose to electron acceptors;<ref name="pmid33291255">{{cite journal |vauthors=Manzar H, Abdulhussein D, Yap TE, Cordeiro MF |title=Cellular Consequences of Coenzyme Q10 Deficiency in Neurodegeneration of the Retina and Brain |journal=Int J Mol Sci |volume=21 |issue=23 |date=December 2020 |page=9299 |pmid=33291255 |pmc=7730520 |doi=10.3390/ijms21239299 |doi-access=free}}{{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref>
* antioxidant activity as a lipid-soluble antioxidant together with [[vitamin E]], scavenging [[reactive oxygen species]] and protecting cells against oxidative stress,<ref name=lpi/><ref name="pmid34064686"/> inhibiting the oxidation of proteins, DNA, and use of vitamin E.<ref name=lpi/><ref name="pmid32349341">{{cite journal |vauthors=Di Lorenzo A, Iannuzzo G, Parlato A, Cuomo G, Testa C, Coppola M, D'Ambrosio G, Oliviero DA, Sarullo S, Vitale G, Nugara C, Sarullo FM, Giallauria F |title=Clinical Evidence for Q10 Coenzyme Supplementation in Heart Failure: From Energetics to Functional Improvement |journal=J Clin Med |volume=9 |issue=5 |date=April 2020 |page=1266 |pmid=32349341 |pmc=7287951 |doi=10.3390/jcm9051266 | doi-access=free}}{{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref>