Mutational analysis of catecholamine binding in tyrosine hydroxylase.
Gabrielle D Briggs, Sarah L Gordon, Phillip W Dickson
Biochemistry | Published : 2011
Tyrosine hydroxylase (TH) performs the first and rate-limiting step in the synthesis of catecholamines, which feed back to regulate the enzyme by irreversibly binding to a high-affinity site and inhibiting TH activity. Phosphorylation of Ser40 relieves this inhibition by allowing dissociation of catecholamine. We have recently documented the existence of a low-affinity catecholamine binding which is dissociable, is not abolished by phosphorylation, and inhibits TH by competing with the essential cofactor, tetrahydrobiopterin. Here, we have substituted a number of active site residues to determine the structural nature of the low- and high-affinity sites. E332D and Y371F increased the IC(50) ..View full abstract