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AN ENDO‐POLYGALACTURONASE IN CUCUMBER FRUIT 1
Author(s) -
MCFEETERS R. F.,
BELL T. A.,
FLEMING H. P.
Publication year - 1980
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1980.tb00873.x
Subject(s) - pectinase , enzyme , chemistry , chromatography , sephadex , enzyme assay , substrate (aquarium) , pectinesterase , biochemistry , pickling , biology , ecology
A homogenous endo‐polygalacturonase (EC 3.2.1.15, ) has been isolated from mature pickling cucumbers. This is the first report of an endo‐polygalacturonase in cucumbers. The enzyme was purified by three chromatography steps on Sephadex cation exchangers. The molecular weight is 35,000 daltons. With polygalacturonic acid as the substrate at an ionic strength (μ) of 0.15, the pH optimum is 5.6. The enzyme is not active at μ= 0.027. Maximum activity occurred at μ= 0.2. The half‐life of the enzyme is 1.2 min at 70°C in pH 5.2, 0.1 M acetate buffer. An inhibitor, isolated from the sericea lespedeza, which inhibits polygalacturonases from fungal sources, also inhibits the cucumber enzyme. This enzyme may be involved in tissue breakdown during the latter stages of fruit development.