The use of continuous‐flow electrophoresis to remove pectin in the purification of the minor pectinesterases in lemon fruits (citrus limon)

Continuous‐flow electrophoresis was used to separate pectin and coloured substances from extracts of lemon pectinesterase. Two minor lemon pectinesterases were subsequently separated from two major pectinesterases, using chromatography on Sephadex G‐75 and CM‐Sephadex C‐50. One minor pectinesterase was stable at low pH, showed the same initial pectinesterase activity at 88°C as at 25°C, and was active at 85°C for 9 min. This enzyme destabilised the cloud of single‐strength lemon juice. It is suggested that the minor pectinesterases might not be true isozymes, but could arise from association of a major enzyme with pectin.