A Biophysical Characterization of the Iron Coordination Environment in Wheat Germ Peroxidase

FERNANDEZ, C O; PODESTA, O; CONVERSO, D A; FERNANDEZ, M E; VILA, AJ

Journal Of Biological Inorganic Chemistry

Society Of Biological Inorganic Chemistry

Año: 1997 vol. 2 p. 218 - 224

0949-8257

The heme protein wheat germ peroxidase (isoenzyme C2) and its cyanide-inhibited form have been investigated by means of electronic, CD and paramagnetic NMR spectroscopy. The data indicate a protein environment of the active site distinct from that of horseradish peroxidase (HRP), with a larger solvent accessibility. The iron is pentacoordinated at neutral and low pH, whereas a hydroxyl anion may be bound at alkaline pH. The fifth axial ligand is a His residue with a partial anionic character, as found in other peroxidases. A spin equilibrium is observed at high enzyme concentrations.