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Molecules Derived from Amino Acids: -Aromatic Amino Acids Are Precursors of Many Plant Substances

المؤلف:  David L. Nelson، Michael M. Cox

المصدر:  Lehninger Principles of Biochemistry

الجزء والصفحة:  859

2026-07-06

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Molecules Derived from Amino Acids: -Aromatic Amino Acids Are Precursors of Many Plant Substances

Phenylalanine, tyrosine, and tryptophan are converted to a variety of important compounds in plants. The rigid polymer lignin, derived from phenylalanine and tyro sine, is second only to cellulose in abundance in plant tissues. The structure of the lignin polymer is complex and not well understood. Tryptophan is also the pre cursor of the plant growth hormone indole-3-acetate, or auxin (Fig. 1a), which has been implicated in the regulation of a wide range of biological processes in plants. Phenylalanine and tyrosine also give rise to many commercially significant natural products, including the tannins that inhibit oxidation in wines; alkaloids such as morphine, which have potent physiological effects; and the flavoring of cinnamon oil (Fig. 1b), nutmeg, cloves, vanilla, cayenne pepper, and other products.

FIGURE 1 Biosynthesis of two plant substances from amino acids. (a) Indole-3-acetate (auxin) and (b) cinnamate (cinnamon flavor).