L-Tyrosine-13C9,15N

L-Tyrosine-13C9,15N is intended for use as an internal standard for the quantification of L-tyrosine by GC- or LC-MS. L-Tyrosine is a non-essential amino acid.1It is produced by hydroxylation of phenylalanine by phenylalanine hydroxylase but can also be obtained from dietary sources or degradation of endogenous proteins, resulting in L-tyrosine release.1,2L-Tyrosine is a precursor in the biosynthesis of catecholamine neurotransmitters, melanins, and thyroid hormones.3Plasma, skeletal muscle, and erythrocyte levels of L-tyrosine are decreased in patients with chronic kidney disease.1