NMR study of the exchange coupling in the trinuclear cluster of the multicopper oxidase Fet3p

MARÍA-EUGENIA ZABALLA; LYNN ZIEGLER; DANIEL J. KOSMAN; ALEJANDRO J. VILA

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2010 vol. 132 p. 11191 - 11196

0002-7863

Fet3p from Saccharomyces cerevisiae is a multicopper oxidase (MCO) which oxidizes Fe2+to Fe3+. The electronic structure of the different copper centers in this family of enzymes has beenextensively studied and discussed for years with a particular focus on the exchange coupling regimein the trinuclear cluster (TNC). Using NMR spectroscopy we have quantified the exchange coupling constant in the type 3 center in a fully metalated oxidase; this value in Fet3p is significantly higher than that reported for proteins containing isolated type 3 centers as tyrosinase. We also provide evidence of exchange coupling between the type 2 and the type 3 Cu2+ ions, which supports the crystallographic evidence of dioxygen binding to the TNC. This work provides the foundation for the application of NMR to these complex systems.