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Phenylalanine ball and stick model spinning. Phenylalanine (symbol Phe or F) [3] is an essential α-amino acid with the formula C 9 H 11 NO 2.It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine.
Phenylalanine is a large, neutral amino acid (LNAA). LNAAs compete for transport across the blood–brain barrier (BBB) via the large neutral amino acid transporter (LNAAT). If phenylalanine is in excess in the blood, it will saturate the transporter. Excessive phenylalanine levels tend to decrease the levels of other LNAAs in the brain.
A small subset of patients with hyperphenylalaninemia shows an appropriate reduction in plasma phenylalanine levels with dietary restriction of this amino acid; however, these patients still develop progressive neurologic symptoms and seizures and usually die within the first 2 years of life ("malignant" hyperphenylalaninemia).
Dopamine has a number of important functions in the brain. This includes critical role in the reward system , motivation and emotional arousal. It also plays an important role in fine motor control and Parkinson's disease has been linked to low levels of dopamine due to the loss of dopaminergic neurons in substantia nigra pars compacta . [ 27 ]
The amino acids phenylalanine and tyrosine are precursors for catecholamines. Both amino acids are found in high concentrations in blood plasma and the brain. In mammals, tyrosine can be formed from dietary phenylalanine by the enzyme phenylalanine hydroxylase, found in large amounts in the liver.
D-Phenylalanine is a psychostimulant and selective norepinephrine releasing agent (NRA) or norepinephrine-preferring norepinephrine–dopamine releasing agent (NDRA). [ 1 ] [ 2 ] The EC 50 Tooltip half-maximal effective concentration values of D -phenylalanine for monoamine release are 106 nM for norepinephrine, 1,355 nM for dopamine , and ...
A ketogenic amino acid is an amino acid that can be degraded directly into acetyl-CoA, which is the precursor of ketone bodies and myelin, particularly during early childhood, when the developing brain requires high rates of myelin synthesis. [1] This is in contrast to the glucogenic amino acids, which are converted into glucose.
Tryptophan hydroxylase (TPH) is an enzyme (EC 1.14.16.4) involved in the synthesis of the monoamine neurotransmitter serotonin. Tyrosine hydroxylase, phenylalanine hydroxylase, and tryptophan hydroxylase together constitute the family of biopterin-dependent aromatic amino acid hydroxylases.