title: Tyrosine hydroxylase: studies on the phosphorylation of a purified preparation of the brain enzyme by the cyclic AMP-dependent protein kinase.
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.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D004789:Enzyme Activation; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000494:pharmacology*; D014446:Tyrosine 3-Monooxygenase / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases