Ortho- and Meta-tyrosine
Three isomers of tyrosine are known. In addition to common amino acid L-tyrosine, which is the para isomer (para-tyr, p-tyr or 4-hydroxyphenylalanine), there are two additional regioisomers, namely meta-tyrosine (m-tyr or 3-hydroxyphenylalanine or L-m-tyrosine) and ortho-tyrosine (o-tyr or 2-hydroxyphenylalanine), that occur in nature. The m-tyr and o-tyr isomers, which are rare, arise through non-enzymatic free-radical hydroxylation of phenylalanine under conditions of oxidative stress.
m-Tyrosine and analogues (rare in nature but available synthetically) have shown application in Parkinson's Disease, Alzheimer's disease and arthritis.
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