Thin-layer isoelectric focusing of multiple forms of tomato pectinesterase

Commercial tomato pectinesterase has been separated into at least eight multiple forms by thin-layer isoelectric focusing. The enzyme components were basic proteins in the range pH 7–9.3, the predominant form having an isoelectric point of 8.6. The enzyme was detected with a staining procedure, employing the reaction of hydroxylamine with the ester groups of pectin. The MW's of the multiple forms of pectinesterase were in the range of 27000 ± 5000.