Principles of Biochemistry Volume 1 - A. Lehninger 1985

Biomolecules
Vitamins and Trace Elements: Their Role in Enzyme Function
Vitamin E protects cell membranes from oxygen

Vitamin E represents a group consisting of at least three compounds: a-, ß-, and у-tocopherol; of these, a-tocopherol is of the greatest importance (Fig. 10-23). Tocopherols are found in vegetable oils, with wheat germ being particularly rich in them. Vitamin E deficiency in rats and other animals leads to Skin flaking, Muscle weakness, and sterility. The term "tocopherol" originates from the Greek word "tokos," which translates to "childbirth." However, it remains unknown whether vitamin E affects human fertility. Tocopherol deficiency in humans causes symptoms such as Liver degeneration and impaired membrane function. Tocopherol molecules consist of an aromatic ring and a long isoprenoid side chain. The precise biological function of vitamin E has not yet been established; it is hypothesized to be involved in protecting Cell Membrane Lipids from the damaging effects of oxygen (Sec. 12.2).

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Fig. 10-21. Different forms of vitamin D

Fig. 10-22. Formation and function of the active form of vitamin D3 — 1,25-dihydroxycholecalciferol.

Fig. 10-23. Vitamin E (a-tocopherol). Isoprene units in the side chain are separated by red dashed lines.



Last update: 06/08/2026

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