Disease relevance of m-Tyrosine

• This phenomenon has been investigated in two patients with phenylketonuria using the putative precursor L-m-tyrosine labelled with deuterium [1].
• For the electrophilic preparation of 6-[18F]fluoro-L-m-tyrosine ([18F]FMT), a PET tracer for measuring changes in dopaminergic function in movement disorders, a novel precursor, N-(tert-butoxycarbonyl)-3-(tert-butoxycarbonyloxy)-6-trimethylstannnyl-L-phenylalanine ethyl ester, was synthesized in four steps and 26% yield starting from L-m-tyrosine [2].

High impact information on m-Tyrosine

• The transamination occurs in about 0.02% of decarboxylations of dopa and m-tyrosine and in about 2% of decarboxylations of alpha-methyldopa and alpha-methyl-m-tyrosine [3].
• After i.v. administration in nonhuman primates and rodents, these new radiofluorinated m-tyrosine analogs accumulate selectively in striatal structures and allow for the detection of additional innervation sites (e.g., brain stem) rich in aromatic amino acid decarboxylase [4].
• These radiofluorinated m-tyrosine presynaptic dopaminergic probes, resistant to peripheral 3-O-methylation, offer a nonpharmacological alternative to the use of catechol-O-methyltransferase inhibitors [4].
• To determine whether hydroxyl radical (HO.) is generated in the human oral cavity during chewing of betel quid, the formation of o- and m-tyrosine from L-phenylalanine was measured [5].
• Purified tyrosine decarboxylase activity also decarboxylated L-DOPA, 5-hydroxytryptophan, 3,4-dihydroxyphenylserine, o-tyrosine, m-tyrosine, phenylalanine, histidine, and tryptophan, which suggested that the purified enzyme was aromatic L-amino acid decarboxylase [6].

Anatomical context of m-Tyrosine

• Measurement of o- and m-tyrosine as markers of oxidative damage in motor neuron disease [7].

Associations of m-Tyrosine with other chemical compounds

• In vitro experiments with rat brain homogenates showed that L-m-tyrosine, m-tyramine and m-octopamine enhanced in efflux of exogenous labeled monamines from brain particles, whereas D-m-tyrosine was completely ineffective [8].
• The O-methylation of labelled catechols is blocked with specific enzyme inhibitors, but dopa decarboxylase substrates derived from m-tyrosine may supplant the catechol tracers [9].
• This suggests that alpha2-adrenoreceptors are involved in m-tyrosine analgesia and that it differs in mechanism from nefopam analgesia [10].
• Such data along with other recently published results permit the conclusion that m-tyramine arises from phenylalanine via m-tyrosine and that p-tyramine arises by decarboxylation of p-tyrosine [11].
• L-5-Hydroxytryptophan, m-tyrosine and o-tyrosine interfered with the decarboxylation of L-dopa in a way that suggested a high activity also towards those substrates [12].

Analytical, diagnostic and therapeutic context of m-Tyrosine

• Assay for L-p-tyrosine in plasma and brain by column liquid chromatography with electrochemical detection using m-tyrosine as the internal standard [13].
• However, although m-tyrosine causes analgesia, it is blocked by yohimbine [10].

References