Topic: tyrosine

Phenylketonuria (PKU) is a rare, metabolic disease caused by a mutation in the gene for the enzyme phenylalanine hydroxylase (PAH). The resulting enzyme defect reduces the transformation of phenylalanine (Phe) to tyrosine and causes the accumulation of Phe in blood and brain. This elevated Phe concentration obstructs the entry of essential amino acids, which serve as neurotransmitter precursors in the brain, affecting proper brain function. It has been observed that PKU is also associated with alterations in circadian rhythms and sleep patterns. However, available data are limited.The Pahenu2

Tyrosine (Y), a non-essential amino acid, is synthesized de novo from phenylalanine and converted into L-DOPA in mammals. In the brain, ROS and RNS are increased both in acute and chronic stress conditions, leading peroxynitrite (PN) production. PN can attack Y residues of functional proteins and turn off their normal functions by nitration, called Y-nitration. Under chronic immobilization stress (CIS), glutamine synthetase (GS) activity is decreased without expression change and the decrement of glutamine (Gln) and glutamate (Glu) is found in the prefrontal cortex (PFC), which results in low-