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Tyrosine hydroxylase: studies on the phosphorylation of a purified preparation of the brain enzyme by the cyclic AMP-dependent protein kinase.

Authors
  • Edelman, A M
  • Raese, J D
  • Lazar, M A
  • Barchas, J D
Type
Published Article
Journal
The Journal of pharmacology and experimental therapeutics
Publication Date
Mar 01, 1981
Volume
216
Issue
3
Pages
647–653
Identifiers
PMID: 6110771
Source
Medline
License
Unknown

Abstract

Tyrosine hydroxylase [L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2](TH) was purified from bovine corpus striatum. The purification involved sequential DEAE cellulose, hydroxylapatite and CM Sephadex C-50 chromatography, followed by glycerol density gradient centrifugation. Final preparations appeared to be 90 to 100% pure as judged by polyacrylamide gel electrophoresis under denaturing conditions in acetic acid-urea. The enzyme was estimated to have a minimum molecular weight of approximately 60,000 daltons. Purified TH could be activated in vitro by incubation with magnesium adenosine triphosphate and the catalytic subunit of cyclic AMP-dependent protein kinase (ATP/protein phosphotransferase; EC 2.7.1.37). When the final purified preparation of TH was incubated under these conditions utilizing [gamma-32P]ATP, it was found to incorporate 0.7 to 0.9 mol of phosphorus/mol of protein. These results suggest that the activation of TH in the presence of phosphorylating conditions is due to its phosphorylation by cyclic AMP-dependent protein kinase.

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