Endo-β-mannanase activity in tomato and other ripening fruits

High amounts of endo-beta -mannanase (EC 3.2.1.78) activity were extracted from tomato (Lycopersicon esculentum Mill.) fruits when a high-salt-containing buffer was used. Two pI forms of the fruit enzyme were identified, one being much more basic than the many seed isoforms, The number of isoforms increased if a protease inhibitor was not used during extraction. The enzyme was found in the ripe fruits of many other species, and was particularly active in those of muskmelon (Cucumis melo L. Cantalupensis Group) and watermelon [Citrullus lanatus (Thunb,) Matsum, and Nak,], In most fruits, enzyme activity was localized in the skin and the epidermal and subepidermal regions. The enzyme in several fruits had a molecular weight of approximate to 40,000 and reacted immunologically with the tomato seed endo-beta -mannanase antibody.