title: Inactivation of tyrosine 3-monooxygenase by acetone precipitation and its restoration by incubation with a sulfhydryl agent and iron.
abstract: The acetone precipitation of a partially purified tyrosine 3-monooxygenase (L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2) resulted in the complete loss of enzymatic activity. The enzymatic activity was restored by incubation with iron and dithiothreitol. The restoration of the activity was a pH-, temperature- and time-dependent reaction. Since cobalt, nickel, copper, zinc, manganese, cadmium, magnesium calcium and barium ions were all ineffective in restoring activity, iron ion appeared to be specifically required in the restoration of the enzyme activity. Dithiothreitol could be partially replaced in the restoration step by glutathione, 2-mercaptoethanol or cysteine.
mesh_terms: D000096:Acetone / Q000494:pharmacology*; D000313:Adrenal Medulla / Q000201:enzymology; D000818:Animals; D011232:Chemical Precipitation; D004229:Dithiothreitol / Q000494:pharmacology; D004793:Enzyme Reactivators; D066298:In Vitro Techniques; D007501:Iron / Q000494:pharmacology*; D051381:Rats; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004793:Enzyme Reactivators; D013439:Sulfhydryl Reagents; D000096:Acetone; D007501:Iron; D014446:Tyrosine 3-Monooxygenase; D004229:Dithiothreitol