Dr. Paul Fitzpatrick's lab studies the regulatory and catalytic properties of the aromatic amino acid hydroxylases tyrosine hydroxylase (TyrH) and phenylalanine hydroxylase (PheH). TyrH, the key enzyme in the biosynthesis of the catecholamine neurotransmitters, utilizes a non-heme iron atom to catalyze oxygen activation and addition. The enzyme is regulated by phosphorylation and feedback inhibition.
PheH, an allosteric enzyme deficient in phenylketonuria, has a similar catalytic mechanism and a similar structure, but differs in its regulatory properties. We utilize a range of biochemical and biophysical techniques, from single turnover kinetics to NMR spectroscopy.
Wang S, Lasagna M, Daubner SC, Reinhart GD, Fitzpatrick PF. Fluorescence spectroscopy as a probe of the effect of phosphorylation at serine 40 of tyrosine hydroxylase on the conformation of its regulatory domain. Biochemistry. 2011 Mar 29;50(12):2364-70.
Fitzpatrick PF. Allosteric regulation of phenylalanine hydroxylase. Arch Biochem Biophys. 2012 Mar 15;519(2):194-201.
Daubner SC, Avila A, Bailey JO, Barrera D, Bermudez JY, Giles DH, Khan
CA, Shaheen N, Thompson JW, Vasquez J, Oxley SP, Fitzpatrick PF. Mutagenesis of a specificity-determining residue in tyrosine hydroxylase establishes that the enzyme is a robust phenylalanine hydroxylase but a fragile tyrosine hydroxylase. Biochemistry. 2013 Feb 26;52(8):1446-55.
Li J, Fitzpatrick PF. Regulation of phenylalanine hydroxylase: conformational changes upon phosphorylation detected by H/D exchange and mass spectrometry. Arch Biochem Biophys. 2013 Jul 15;535(2):115-9.
Zhang S, Huang T, Ilangovan U, Hinck AP, Fitzpatrick PF. The Solution Structure of the Regulatory Domain of Tyrosine Hydroxylase. J Mol Biol. 2013 Dec 17.