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. Author manuscript; available in PMC: 2018 Sep 1.
Published in final edited form as: Neuropharmacology. 2017 May 29;123:159–174. doi: 10.1016/j.neuropharm.2017.05.030

Table 3.

Affinity (Km) of TH v. Levels of aromatic amino acids in rat brain

Kma (μM) Tissueb (ng/mg protein) Intracellularc (μM)
L-tyrosine 8.6 – 10.8 1.1 172
L-phenylalanine 49.3 – 160 0.85 130
L-tryptophan 210 – 540 0.20 31
a

cloned rat tyrosine hydroxylase (TH) expressed heterologously and assayed in presence of tetrahydrobiopterin (Daubner et al., 1992;Fitzpatrick, 1991),

b

average tissue levels in rat medial prefrontal cortex and striatum (Bongiovanni et al., 2010),

c

calculated for 122 mg/g protein (Banay-Schwartz et al., 1992), 78% water content (Schwab et al., 1997) in rat brain tissue and assuming homogeneous distribution of amino acids in intracellular water.