L-phenylalanine catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of phenylalanine, 2-amino-3-phenylpropanoic acid. [GOC:go_curators]

The L-phenylalanine catabolic process is a complex metabolic pathway responsible for the breakdown of the amino acid L-phenylalanine. It begins with the hydroxylation of L-phenylalanine to L-tyrosine, catalyzed by the enzyme phenylalanine hydroxylase (PAH). This step requires molecular oxygen and tetrahydrobiopterin as cofactors. L-tyrosine is then converted to L-dopa, a precursor to dopamine and other neurotransmitters, by the enzyme tyrosine hydroxylase. L-dopa can be further metabolized via two distinct pathways:

The first pathway involves decarboxylation of L-dopa to dopamine by aromatic-L-amino-acid decarboxylase. Dopamine can then be converted to norepinephrine by dopamine beta-hydroxylase, and norepinephrine can be further metabolized to epinephrine by phenylethanolamine N-methyltransferase.

The second pathway involves the conversion of L-dopa to homogentisic acid via a series of enzymatic reactions. Homogentisic acid is then further metabolized to maleylacetoacetate by homogentisate 1,2-dioxygenase. Maleylacetoacetate is subsequently isomerized to fumarylacetoacetate by maleylacetoacetate isomerase. Finally, fumarylacetoacetate is cleaved to fumarate and acetoacetate by fumarylacetoacetate hydrolase. Fumarate enters the citric acid cycle, while acetoacetate is converted to acetyl-CoA, which can be used for energy production or fatty acid synthesis.

Genetic defects in the enzymes involved in L-phenylalanine catabolism, particularly PAH, can lead to phenylketonuria (PKU), a rare metabolic disorder characterized by the accumulation of phenylalanine in the blood. PKU can cause severe neurological damage if left untreated.'
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Proteins (2)

Compounds (5)