Dopamine, in the presence of tyrosinase, covalently modifies and inactivates tyrosine hydroxylase

Yimei Xu, Alan H. Stokes, Robert Roskoski, Kent Vrana

Research output: Contribution to journalArticle

138 Citations (Scopus)

Abstract

Dopamine has been implicated as a potential mediating factor in a variety of neurodegenerative disorders. Dopamine can be oxidized to form a reactive dopamine quinone that can covalently modify cellular macromolecules including protein and DNA. This oxidation can be enhanced through various enzymes including tyrosinase and/or prostaglandin H synthase. One of the potential targets in brain for dopamine quinone damage is tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis. The present studies demonstrated that dopamine quinone, the formation of which was enhanced through the activity of the melanin biosynthetic enzyme, tyrosinase, covalently modified and inactivated tyrosine hydroxylase. Dihydroxyphenylalanine (DOPA; the catechol-containing precursor of dopamine) also inactivated tyrosine hydroxylase under these conditions. Catecholamine- mediated inactivation occurred with both purified tyrosine hydroxylase as well as enzyme present in crude pheochromocytoma homogenates. Inactivation was associated with covalent incorporation of radiolabelled dopamine into the enzyme as assessed by immunoprecipitation, size exclusion chromatography, and denaturing sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis. Furthermore, the covalent modification and inactivation of tyrosine hydroxylase was blocked by antioxidant compounds (dithiothreitol, reduced glutathione, or NADH). In addition to kinetic feedback inhibition and the formation of an inhibitory dopamine/Fe+3 complex, these findings suggest that a third mechanism exists by which dopamine (or DOPA) can inhibit tyrosine hydroxylase, adding further complexity to the regulation of catecholamine biosynthesis.

Original languageEnglish (US)
Pages (from-to)691-697
Number of pages7
JournalJournal of Neuroscience Research
Volume54
Issue number5
DOIs
StatePublished - Dec 1 1998

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Monophenol Monooxygenase
Tyrosine 3-Monooxygenase
Dopamine
Catecholamines
Enzymes
Dihydroxyphenylalanine
Dithiothreitol
Melanins
Pheochromocytoma
Prostaglandin-Endoperoxide Synthases
Immunoprecipitation
Neurodegenerative Diseases
NAD
Gel Chromatography
Glutathione
Polyacrylamide Gel Electrophoresis
Antioxidants
Sodium
DNA
Brain

All Science Journal Classification (ASJC) codes

  • Cellular and Molecular Neuroscience

Cite this

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title = "Dopamine, in the presence of tyrosinase, covalently modifies and inactivates tyrosine hydroxylase",
abstract = "Dopamine has been implicated as a potential mediating factor in a variety of neurodegenerative disorders. Dopamine can be oxidized to form a reactive dopamine quinone that can covalently modify cellular macromolecules including protein and DNA. This oxidation can be enhanced through various enzymes including tyrosinase and/or prostaglandin H synthase. One of the potential targets in brain for dopamine quinone damage is tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis. The present studies demonstrated that dopamine quinone, the formation of which was enhanced through the activity of the melanin biosynthetic enzyme, tyrosinase, covalently modified and inactivated tyrosine hydroxylase. Dihydroxyphenylalanine (DOPA; the catechol-containing precursor of dopamine) also inactivated tyrosine hydroxylase under these conditions. Catecholamine- mediated inactivation occurred with both purified tyrosine hydroxylase as well as enzyme present in crude pheochromocytoma homogenates. Inactivation was associated with covalent incorporation of radiolabelled dopamine into the enzyme as assessed by immunoprecipitation, size exclusion chromatography, and denaturing sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis. Furthermore, the covalent modification and inactivation of tyrosine hydroxylase was blocked by antioxidant compounds (dithiothreitol, reduced glutathione, or NADH). In addition to kinetic feedback inhibition and the formation of an inhibitory dopamine/Fe+3 complex, these findings suggest that a third mechanism exists by which dopamine (or DOPA) can inhibit tyrosine hydroxylase, adding further complexity to the regulation of catecholamine biosynthesis.",
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Dopamine, in the presence of tyrosinase, covalently modifies and inactivates tyrosine hydroxylase. / Xu, Yimei; Stokes, Alan H.; Roskoski, Robert; Vrana, Kent.

In: Journal of Neuroscience Research, Vol. 54, No. 5, 01.12.1998, p. 691-697.

Research output: Contribution to journalArticle

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T1 - Dopamine, in the presence of tyrosinase, covalently modifies and inactivates tyrosine hydroxylase

AU - Xu, Yimei

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