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an organic molecule, usually containing phosphorus and some vitamins, sometimes separable from the enzyme protein; a coenzyme and an apoenzyme must unite in order to function (as a holoenzyme).
coenzyme A a coenzyme essential for carbohydrate and fat metabolism; among its constituents are pantothenic acid and a terminal SH group, which forms linkages with various acids, e.g., acetic acid (acetyl CoA) and fatty acids (acyl CoA); abbreviated CoA.
coenzyme Q any of a group of related quinones occurring in the lipid fraction of mitochondria and serving, along with the cytochromes, as an intermediate in electron transport; they are similar in structure and function to vitamin K1.
co·en·zyme Q (CoQ, Q),(kō-en'zīm),
Designation applied to ubiquinones with isoprenoid side chains consisting of variable numbers of isoprene units. CoQ mediates electron transfer between cytochromes b and c, and is chemically similar to vitamins E and K and to other tocopherols, quinones, and tocols. the length of the isoprenoid side chain distinguishes one type of CoQ from another; for example, ubiquinone-10, the typical mammalian ubiquinone, has a side-chain of 10 isoprene units.
Quinones with isoprenoid side chains (specifically, ubiquinones) that mediate electron transfer between cytochrome b and cytochrome c.