Possible Interaction: Tryptophan and Tyrosine

“Amino acid tyrosine Tyr ) that usually coexist with Trp in biological fluids can significantly interfere with reliable determination of Trp.”

“The ingestion of large neutral amino acids (LNAA), notably tryptophan, tyrosine and the branched-chain amino acids (BCAA), modifies tryptophan and tyrosine uptake into brain and their conversion to serotonin and catecholamines, respectively.”

“ Tyrosine phosphorylation of TRP family members also results in increased channel activity; however, the link between the two events is unclear.”

“In consideration of combined participation of tyrosine and tryptophan in the synthesis of melanin and its breakdown, the possible influence of different enzymatic reactions, like mono-oxygenase, dioxygenase, and deamination, has been suggested.”

“It has been suggested that tyrosine may compete with tryptophan for uptake into the central nervous system, and or inhibit tryptophan hydroxylase activity reducing serotonin production.”

“Here, I propose a chaos theory for schizophrenia, mania, and depression using the competitive interaction between tryptophan and tyrosine with regard to the blood-brain barrier and coenzyme tetrahydrobiopterin.”

“ L-Trp also had much higher inhibitory activity on the cytochrome P-450-dependent lipid peroxidation than the previously identified antioxidants of HPE, L-phenylalanine, L-tyrosine and uracil.”

“Since diet-… in plasma tryptophan and tyrosine ratios in animal are known … parallel alterations in brain tryptophan and tyrosine and levels, and thus in the rates of brain serotonin and catecholamines synthesis, out data … the ingestion of carbohydrates and protein may also normally affect brain monoamine synthesis in humans.”

“However, a competitive reciprocity exists between the uptake of tryptophan and tyrosine because TRP increases significantly in the platelets after administration, and tyrosine is reduced.”

“Since diet-induced … plasma trypotphan and tyrosine ratios in animals are known … cause parallel alterations in brain tryptophan and tyrosine levels, and thus in the rates of brain serotonin and catecholamine synthesis, our data … that ingestion of carbohydrates and protein may also normally affected brain monoamine synthesis in humans.”