Coenzyme Q

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Last update: Friday, 17 Nov 2023 at 11.53 am.

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Coenzyme Q, ubiquinone

Coenzyme Q, semiquinone

File:Ubihydroquinone.svg

Coenzyme Q, ubiquinol

Coenzyme Q (also ubiquinone, coenzyme Q10, CoQ) belongs to oxidoreductase coenzymes. It is part of the mitochondrial respiratory chain. It contains an isoprenoid side chain and therefore belongs to the isoprenoids. It can contain a different number of isoprene units in the side chain (often 10 → therefore coenzyme Q10).

Coenzyme Q and its role in the respiratory chain[edit | edit source]

The quinone structure of ``ubiquinone (Q) can accept one electron and one proton and change to ``semiquinone (QH^.). By accepting an additional electron and proton, semiquinone produces hydroquinone (ubiquinol, QH₂').^[1] Thus, ubiquinone (Q) can accept 2 electrons and 2 protons and ubiquinol (QH₂) is formed from it.

Thanks to the isoprene side chain, coenzyme Q is anchored in the cell membrane, where it serves as a mobile electron carrier'. All 3 forms of coenzyme Q mentioned above serve to transfer electrons from complex I (or II) to complex III.