Purification of Soluble Membrane-Bound Ambystoma mexicanum Epidermal Lipoxygenase from E. coli and Its Growth Effect on Human Fetal Foreskin Fibroblast

Abstract

Lipoxygenases are non-heme iron-containing lipid dioxygenases enzymes that catalyze the hydroperoxidation of lipids. The Mexican axolotl (Ambystoma mexicanum) is a prominent source of the enzyme with a regeneration capacity in limbs. It has been shown that transfected human osteosarcoma and keratinocyte cells with epidermal lipoxygenase (LOXe) have an increased rate of cell migration. In the present study, LOXe, a peripheral membrane protein, was produced in Escherichia coli. The enzyme was purified using different detergents, anionic solutions, and gel filtration chromatography. Kinetic assay of the enzyme activity was carried out by the spectroscopy method using arachidonic acid as a substrate. Finally, the enzyme was characterized and its growth effect on human fibroblast cells was examined by MTT viability assay. Enzyme kinetic parameters including K_m of 90.4 µM and V_max of 2.63 IU were determined for LOXe. The enzyme with 0.1 nM end concentration promoted the growth of 5000 cells/well human fibroblast cells up to 11% (P < 0.01). In the present study, we introduce an E. coli expression system to produce an excessive amount of soluble LOXe and the efficient purification method to provide a soluble and active form of LOXe that is effective in stimulating human fibroblast cell proliferation.