Abstract

Peroxidase activity and 3,4-dihydroxyphenylalanine (DOPA) were found in vacuoles isolated from mesophyll protoplasts of Vicia faba L. A peroxidase isozyme localized in vacuoles migrated to the cathode during electrophoresis at pH 8.7, indicating that the vacuole peroxidase was a basic isozyme. When isolated vacuoles were treated with 2 mM H2O2, dopachrome, a product of oxidation of DOPA, was formed in a reaction that was inhibited by KCN and NaN3. These results suggest that DOPA can serve as a donor of electrons to the peroxidase in vacuoles.

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