Purification and characterization of a linoleate isomerase from <i>Lactobacillus plantarum</i> ZS2058

Abstract

Linoleate isomerase (EC 5.2.1.5) catalyzes the isomerization of linoleic acid to generate conjugated linoleic acid. Previously, we isolated a strain of Lactobacillus plantarum ZS2058 with great capacity for producing conjugated linoleic acid from fermented vegetables. This work aimed to purify the linoleate isomerase from L. plantarum ZS2058 and investigate its characteristics. Electrophoresis of the purified enzyme by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed a single band of protein with a molecular mass of 66 kDa. The purified linoleate isomerase was active, with a specific activity of 3.71 nmol/ [min· (mg·protein)] and a Km of 21.5 ìM for linoleic acid. The optimal pH and temperature for enzyme activity were determined to be pH 6.5 and 35°C respectively. No external cofactors or energy sources were required for this activity. Metal chelators, ethylenediamine tetra-acetic acid (EDTA) and ethylene glycol tetraacetic acid and (EGTA), and metal ions had no effect on enzyme activity.

Key words: Conjugated linoleic acid, Lactobacillus plantarum ZS2058, linoleate isomerase, purification, characterization.