PURIFICATION AND PROPERTIES OF THE MAJOR PECTINESTERASES IN LEMON FRUITS (CITRUS-LIMON)

Pectinesterase from lemon was separated into seven fractions by chromatography on CM-Sephadex C-50. Purification was hindered by the presence of pectin, for which the pectinesterase had a high affinity. Two major pectinesterases were purified: one was located solely in the peel and the other in the endocarp. They possessed similar molecular weights (35 kDa and 33 kDa, respectively) and high isoelectric points (> 11, and c 9). They required the presence of cations for optimal activity, the peel pectinesterase requiring a higher concentration of cations than the endocarp enzyme. Both enzymes were completely inactivated at temperatures above 88-degrees-C. Although neither enzyme destabilised the cloud of lemon juice or of comminuted lemon beverages, they caused cloud destabilisation of orange juice.