Separation of pectin methylesterases and polygalacturonases on monolithic columns

The most abundant isoforms of tomato pectin methylesterase (PME; EC 3.1.1.11; M(r) 26 kDa), polygalacturonase (PG; EC 3.2.1.15; PG1 with M(r) 82 kDa) and a basic protein with M(r) 42 kDa and unknown function were isolated from fresh tomato fruit by a fast chromatographic procedure on a Convective Interaction Media (CIM) short monolithic disk column bearing carboxymethyl (CM) groups. The extraction of the targeted enzymes with 1.2M NaCl solution was followed by precipitation with ammonium sulfate at 60% of saturation, solubilisation of the pellet in 0.5M NaCl and fractionation using a linear gradient from 0 to 700 mM NaCl. Among six fractions five had PME activity and four had PG activity, while one fraction containing a pure protein with M(r) 42 kDa with neither of these activities. Two concentrated fractions, one with PG and one with PME were further purified. A linear gradient from 0 to 500 mM NaCl with 20% CH(3)CN in the mobile phase was used for the PG fraction and two CM disks and a linear gradient from 0 to 200 mM NaCl were used for the PME fraction as a greater capacity was necessary in this case. From 4 kg of fresh tomato flesh we obtained 22 mg of purified PME, 1.8 mg of purified, active PG1, 13.5mg of additional basic protein and a fraction with PG2 contaminated by a PME isoform. Carboxymethyl CIM disk short monolithic columns are convenient for semi-preparative and analytical work with tomato fruit pectolytic enzymes.