TOMATO FRUIT CARBOXYPEPTIDASE - PROPERTIES, INDUCTION UPON WOUNDING, AND IMMUNOCYTOCHEMICAL LOCALIZATION

Carboxypeptidase activity was characterized during ripening and woundi ng of tomato (Lycopersicon esculentum) fruit. The fruit enzyme shares substrate specificity and susceptibility to the inhibitors diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride with other plant ca rboxypeptidases. The abundance and stability of wound-induced carboxyp eptidase were developmentally regulated. Oxidative stress caused by cu pric ions impaired the membrane permeability in the slices from pink f ruit, resulting in leakage of the carboxypeptidase into the medium and in its redistribution in the cell. The patterns of carboxypeptidase a ctivity did not parallel the cupric ion effect on ethylene levels. Imm unogold electron microscopy studies indicated that the fruit carboxype ptidase is associated with electron-dense inclusions in the vacuole.