Purification of isocitrate lyase from Escherichia coli and watermelon using fast protein liquid chromatography

The enzyme isocitrate lyase has been purified to gel electrophoretic homogeneity from Escherichia coli and watermelon. From cotyledons of the latter source, the enzyme is obtained in less than 8 hours after precipitation with (NH4)2 SO4 followed by fractionation on cationic Mono S microbeads and anionic Mono Q microbeads using Fast Protein Liquid Chromatography (FPLC). From a genetically engineered E. coli strain, in which high-level expression of isocitrate lyase occurs, the enzyme has been purified in one step from the high-speed supernatant using a Mono Q column with FPLC. These purifications, both of which give satisfactory yields, potentiate rapid access to isocitrate lyase from both prokaryotic and eukaryotic sources.