Knowra Phenylpropanoid pathway Phenylpropanoid pathway The phenylpropanoid pathway is a plant metabolic network that converts phenylalanine into diverse phenolic compounds, including lignin precursors, flavonoids, and defense chemicals.
Phenylalanine ammonia-lyase : An enzyme that converts phenylalanine into trans-cinnamic acid by removing ammonia. It catalyzes the pathway’s entry reaction, connecting primary metabolism to phenylpropanoid production.
Lignin : A complex aromatic polymer deposited in plant cell walls, where it strengthens tissues and limits water loss. Phenylpropanoid-derived monolignols are oxidatively coupled to build this polymer.
Phenylalanine : An aromatic amino acid used in protein synthesis and as a precursor for many plant specialized metabolites. It is the principal starting substrate named in the pathway’s defining reaction sequence.
Plant cell wall : A structural extracellular matrix surrounding plant cells, composed chiefly of cellulose, hemicellulose, and pectin. Lignin made through this pathway reinforces selected cell walls.
Cinnamate 4-hydroxylase : A cytochrome P450 enzyme that hydroxylates trans-cinnamic acid to form p-coumaric acid. It carries out an early oxidation step after phenylalanine ammonia-lyase.
Flavonoid : A large class of plant polyphenols with roles in pigmentation, signaling, and protection. The pathway supplies p-coumaroyl-CoA for the flavonoid biosynthetic branch.
Trans-cinnamic acid : An aromatic hydroxy-free carboxylic acid produced from phenylalanine by ammonia elimination. It is the first committed intermediate after phenylalanine is deaminated.
Plant defense against herbivory : The physical and chemical strategies plants use to reduce damage from animals that eat them. Pathway products such as tannins and other phenolics can deter feeding or impair digestion.
4-Coumarate—CoA ligase : An enzyme family that activates hydroxycinnamic acids by attaching coenzyme A. Its products feed lignin, flavonoid, and other branches of the pathway.
Anthocyanin : A water-soluble flavonoid pigment that gives many flowers, fruits, and leaves red, purple, or blue colors. Anthocyanins are colored products of a downstream branch originating in phenylpropanoid metabolism.
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