-Carotene

-Carotene is an isoprenoid found abundantly in carrots that is an accessory photosynthetic pigment and a precursor of all-trans-retinol (Vitamin A) (Figure 19.25).

> -carotene + 2 NADH (or NADPH) + H+ <=> 2 All-trans-Retinol + 2 NAD+ (or 2 NADP+) (two reactions catalyzed by a dioxygenase and a reductase)

-Carotene is made in plants from lycopene.

See also: Lipid-Soluble Vitamins, Figure 17.7, Lycopene

INTERNET LINK: Retinol Metabolism