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Partial Separation and Characterization of Papaya Endo‐ and Exo‐Polygalacturonase
Author(s) -
CHAN HARVEY T.,
TAM STEVEN Y.T.
Publication year - 1982
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1982.tb04965.x
Subject(s) - chemistry , pectinase , size exclusion chromatography , enzyme , chromatography , kinetics , biochemistry , physics , quantum mechanics
Exo‐ and endo‐polygalacturonases (EC 3.2.1.40 and EC 3.2.1.15) in papayas were extracted, purified 20‐ and 90‐fold, respectively, and characterized. Both enzymes functioned optimally at pH 4.6 and 45°C. Heat inactivation of the papaya PGases was biphasic and both phases followed first order kinetics. Decreasing the pH from 4.6 to 3.6 decreased the time required for their heat inactivation. The activation energies for the thermal inactivation at pH 3.6 and 4.6 were 85 and 92 kcal/mol, respectively, for endo‐PGase (PG I) and 140 and 102 kcal/mol, respectively, for exo‐PGase (PG II). The apparent molecular weight was determined by gel filtration to be 164,000 daltons for PG I and 34,000 daltons for PG II.