Endo-beta-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-contain ing 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 i ncreased if a protease inhibitor was not used during extraction. The enzyme was found in the ripe fruits of many other species, and was particularly a ctive in those of muskmelon (Cucumis melo L. Cantalupensis Group) and water melon [Citrullus lanatus (Thunb,) Matsum, and Nak,], In most fruits, enzyme activity was localized in the skin and the epidermal and subepidermal regi ons. The enzyme in several fruits had a molecular weight of approximate to 40,000 and reacted immunologically with the tomato seed endo-beta -mannanas e antibody.