pH-dependent Release of Catecholamines From Tyrosine Hydroxylase and the Effect of Phosphorylation of Ser-40

FEBS Lett. 1990 Mar 26;262(2):363-5. doi: 10.1016/0014-5793(90)80230-g.

Abstract

Bovine adrenal tyrosine hydroxylase (TH) is isolated in a partially inhibited state with the feed-back inhibitors adrenaline and noradrenaline tightly coordinated to high-spin (S = 5/2) Fe(III) at the active site. In addition to the charge-transfer interaction with iron, an additional charged group in the polypeptide chain, with an apparent pKa of about 5.3 at 4 degrees C, is involved in the binding of catecholamines. Protonation of this group increases the pseudo-first order rate constant for the dissociation of the TH-[3H]noradrenaline complex more than 100-fold at 4 degrees C. At pH 7.0 and 30 degrees C, phosphorylation of Ser-40 causes a 6-fold increase in the rate constant for this dissociation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Glands / enzymology*
  • Animals
  • Binding Sites
  • Cattle
  • Epinephrine / metabolism*
  • Hydrogen-Ion Concentration
  • Kinetics
  • Norepinephrine / metabolism*
  • Phosphorylation
  • Rats
  • Serine / metabolism
  • Tyrosine 3-Monooxygenase / metabolism*

Substances

  • Serine
  • Tyrosine 3-Monooxygenase
  • Norepinephrine
  • Epinephrine