COENZYME Q
Craneetal (1959) have demonstrated that coenzyme Q and certain other ubiquinones are components of mitochondrial lipids. These substances serve as electron transport agents and are involved in the formation of ATP at a cytochrome a. Roles (1967) has classified the coenzyme Q group as vitamins because of their ability to cure (or protect against) vitamin E deficiency in
several animal speces. Some of the coenzymes alsoparticipate in electron transport and/or oxidative phosphorylation. Various homologues of coenzyme Q, containing 6 to 10 isoprene units, have been isolated from various microbes, chloroplasts of green plants and mitochondria of animals. These have the same quinonoid nucleus (in Fig.) but differ in the number of isoprenoid units in the side chain. For example, coenzyme Q from animal source has 10 isoprene units and is, henceforth, called coenzyme Q10 or ubiquinone50 (50 carbon atoms, i.e., 10 isoprene units, in the side chain), where as the one from bacteria has less than 10 isoprene units. Mycobacteria, however, contain no coenzyme Q.
several animal speces. Some of the coenzymes alsoparticipate in electron transport and/or oxidative phosphorylation. Various homologues of coenzyme Q, containing 6 to 10 isoprene units, have been isolated from various microbes, chloroplasts of green plants and mitochondria of animals. These have the same quinonoid nucleus (in Fig.) but differ in the number of isoprenoid units in the side chain. For example, coenzyme Q from animal source has 10 isoprene units and is, henceforth, called coenzyme Q10 or ubiquinone50 (50 carbon atoms, i.e., 10 isoprene units, in the side chain), where as the one from bacteria has less than 10 isoprene units. Mycobacteria, however, contain no coenzyme Q. Another alleged fat-soluble vitamin is stigmasterol.
It is a plant sterol and has been isolated from soybean and wheat germ oils. It in present in alfalfa and fresh cream. Chemically, it resembles ergosterol closely and contains only 2 double bonds at carbon postitons 5—6 and 22—23 (in fig). The absence of stigmasterol causes stiffness of the wrists and elbows of the guinea pigs. For this reason, it is commonly called as ‘antistiffness factor’.The muscles atrophy and become streaked.
It is a plant sterol and has been isolated from soybean and wheat germ oils. It in present in alfalfa and fresh cream. Chemically, it resembles ergosterol closely and contains only 2 double bonds at carbon postitons 5—6 and 22—23 (in fig). The absence of stigmasterol causes stiffness of the wrists and elbows of the guinea pigs. For this reason, it is commonly called as ‘antistiffness factor’.The muscles atrophy and become streaked.
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