ubiquinone11

Ubiquinone-11, also known as ubiquinone-11 or Q11, is a member of the ubiquinone family of lipophilic quinones characterized by a benzoquinone head and a long isoprenoid side chain containing 11 isoprene units. The length of the polyprenyl tail determines membrane affinity and localization, with longer tails resulting in stronger membrane association. In nature, ubiquinones display a range of tail lengths; ubiquinone-10 is the predominant form in humans, while Q11 has been reported in certain bacteria and archaea, though it is much less common in vertebrates. The exact distribution depends on species and environmental conditions.

The primary biological role of ubiquinones is as electron carriers in the mitochondrial or bacterial respiratory chains. The oxidized quinone accepts two electrons and two protons to become ubiquinol, and ubiquinol donates those electrons further along the chain, coupling electron transfer to proton translocation and ATP synthesis. The hydrophobic tail anchors the molecule in the lipid membrane, placing the headgroup at the membrane surface where redox reactions occur. In addition to electron transport, ubiquinones can act as antioxidants in membranes, stabilizing lipid radicals.

Biosynthesis of ubiquinones involves a conserved pathway that builds the benzoquinone head and attaches a polyprenyl tail of defined length. The tail length is controlled by specific prenyltransferases and related enzymes; variants that produce longer tails, such as Q11, are observed in some organisms, contributing to species-specific differences in respiratory efficiency and membrane properties.

In humans, ubiquinone-10 is the dominant endogenous form, and ubiquinone-11 is primarily of interest in basic biochemical research and comparative biology. Coenzyme Q10 is also used commercially as a dietary supplement; ubiquinone-11 is rarely used in supplements.