JBC, Vol. 252, Issue 10, 3160-3169, May, 1977
Bovine adrenal tyrosine hydroxylase: purification and properties
R. Hoeldtke and S. Kaufman
Bovine adrenal tyrosine hydroxylase has been obtained in a form that is 85
to 90% pure. Sodium dodecyl sulfate-gel electrophoresis and density
gradient centrifugation studies have established that the subunit molecular
weight of the chymotrypsin-solubilized enzyme is 34,000. The presence of
iron in the purified enzyme (0.50 to 0.75 mol of iron/mol of enzyme) has
been established. Crude particulate tyrosine hydroxylase can be activated
by the phospholipid, phosphatidyl-L-serine, or by exposure to enzymatic
phosphorylating conditions. Both forms of activation lower the Km of the
enzyme for its 2-amino-4-hydroxypteridine cofactor. By contrast, tyrosine
hydroxylase that has been solubilized by chymotrypsin cannot be activated
by either of these methods.