1H- and 15N-NMR study of the binding of thiocyanate to chemically modified horseradish peroxidase and involvement of salt bridge.

The chemical modification of native horseradish peroxidase (HRP) has been carried out by esterification of the heme propionic group. 15N- and 1H-NMR studies on binding of thiocyanate ion to chemically modified HRP have been utilized to demonstrate the existence of salt bridge between the heme propionic acid and distal amino acid group. The catalyzed oxidation of thiocyanate by the native HRP, and the chemically modified HRP has also been studied at different pH, and the significance of the salt bridge discussed.