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Tyrosine Hydroxylase Information

Tyrosine hydroxylase or tyrosine 3-monooxygenase is the enzyme responsible for catalyzing the conversion of the amino acid L-tyrosine to dihydroxyphenylalanine (DOPA).[1][2] It does so using tetrahydrobiopterin as a coenzyme. DOPA is a precursor for dopamine, which, in turn, is a precursor for norepinephrine (noradrenaline) and epinephrine (adrenaline). In humans, tyrosine hydroxylase is encoded by the TH gene.[2]

Contents

Reaction

The enzyme, an oxygenase, is found in the cytosol of all cells containing catecholamines. This initial reaction is the rate limiting step in the production of catecholamines.

The enzyme is highly specific, not accepting indole derivatives - which is unusual as many other enzymes involved in the production of catecholamines do.

Tyrosine hydroxylase catalyzes tyrosine to dihydroxyphenylalanine

Clinical significance

Tyrosine hydroxylase can be inhibited by the drug α-methyl-para-tyrosine (Metirosine). This inhibition can lead to a depletion of dopamine and norepinepherine in the brain due to the lack of the precursor L-Dopa (L-3,4-dyhydroxyphenylalanine) which is synthesized by tyrosine hydroxylase. This drug is rarely used and can cause depression, but it is useful in treating pheochromocytoma and also resistant hypertension.

Dopamine

Tyrosine hydroxylase is an autoantigen in Autoimmune Polyendocrine Syndrome (APS) type I.[3]

Older examples of inhibitors mentioned in the literature include oudenone[4] and aquayamycin.[5]

References

  1. ^ Kaufman S (1995). "Tyrosine hydroxylase". Adv. Enzymol. Relat. Areas Mol. Biol. 70: 103–220. doi:10.1002/9780470123164.ch3. PMID 8638482.
  2. ^ a b Nagatsu T (1995). "Tyrosine hydroxylase: human isoforms, structure and regulation in physiology and pathology". Essays Biochem. 30: 15–35. PMID 8822146.
  3. ^ Hedstrand H, Ekwall O, Haavik J, Landgren E, Betterle C, Perheentupa J, Gustafsson J, Husebye E, Rorsman F, Kämpe O (January 2000). "Identification of tyrosine hydroxylase as an autoantigen in autoimmune polyendocrine syndrome type I". Biochem. Biophys. Res. Commun. 267 (1): 456–61. doi:10.1006/bbrc.1999.1945. PMID 10623641.
  4. ^ Ono M, Okamoto M, Kawabe N, Umezawa H, Takeuchi T (March 1971). "Oudenone, a novel tyrosine hydroxylase inhibitor from microbial origin". J. Am. Chem. Soc. 93 (5): 1285–6. doi:10.1021/ja00734a054. PMID 5545929.
  5. ^ Ayukawa S, Takeuchi T, Sezaki M, Hara T, Umezawa H (May 1968). "Inhibition of tyrosine hydroxylase by aquayamycin". J. Antibiot. 21 (5): 350–3. PMID 5726288.

Further reading

· · PDB gallery
1toh: TYROSINE HYDROXYLASE CATALYTIC AND TETRAMERIZATION DOMAINS FROM RAT
2toh: TYROSINE HYDROXYLASE CATALYTIC AND TETRAMERIZATION DOMAINS FROM RAT

External links

· · Carrier proteins, metalloproteins: iron-binding proteins
heme Ferritin (Bacterioferritin) - Lactoferrin - Transferrin
nonheme Hemerythrin - Inositol oxygenase - Iron-sulfur protein - Lipoxygenase - Tyrosine hydroxylase
· · Oxidoreductases: dioxygenases, including steroid hydroxylases (EC 1.14)
1.14.11: 2-oxoglutarate Prolyl hydroxylase - Lysyl hydroxylase
1.14.13: NADH or NADPH Flavin-containing monooxygenase (FMO1, FMO2, FMO3, FMO4, FMO5) - Nitric oxide synthase (NOS1, NOS2, NOS3) - Cholesterol 7 alpha-hydroxylase - Methane monooxygenase - 3A4 - Lanosterol 14 alpha-demethylase
1.14.14: reduced flavin or flavoprotein 19A1 - 2D6 - 2E1
1.14.15: reduced iron-sulfur protein 11B1 - 11B2 - 11A1
1.14.16: reduced pteridine (BH4 dependent) Phenylalanine hydroxylase - Tyrosine hydroxylase - Tryptophan hydroxylase
1.14.17: reduced ascorbate Dopamine beta hydroxylase
1.14.18-19: other Tyrosinase - Stearoyl-CoA desaturase-1
1.14.99 - miscellaneous Cyclooxygenase - Heme oxygenase (HMOX1) - Squalene monooxygenase - 17A1 - 21A2
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· · Metabolism: amino acid metabolism · neurotransmitter enzymes
monoamine
histidinehistamine anabolism: Histidine decarboxylase catabolism: Histamine N-methyltransferase · Amine oxidase
tyrosinedopamineepinephrine anabolism: Tyrosine hydroxylase · Aromatic L-amino acid decarboxylase · Dopamine beta hydroxylase · Phenylethanolamine N-methyltransferase catabolism: Catechol-O-methyl transferase · Monoamine oxidase
glutamateGABA anabolism: Glutamate decarboxylase catabolism: 4-aminobutyrate aminotransferase · 4-aminobutyrate transaminase
tryptophanserotoninmelatonin Tryptophan hydroxylase · Aromatic L-amino acid decarboxylase · Acetylserotonin O-methyltransferase
arginineNO Nitric oxide synthase (NOS1, NOS2, NOS3)
cholineAcetylcholine anabolism: Choline acetyltransferase catabolism: Cholinesterase (Acetylcholinesterase, Butyrylcholinesterase)

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Categories: Human proteins | Enzymes | EC 1.14.16

 

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