Purification and characterization of an intracellular esterase from Propionibacterium freudenreichii ssp. freudenreichii ITG 14

An intracellular esterase from Propionibacterium freudenreichii ssp. freudenreichii ITG 14 was purified by anion exchange and gel filtration chromatography. The enzyme had a molecular weight of 47 400 g . mol -1 as determined by gel filtration chromatography, with an optimum activity on -naphthyl-acetate at pH 6.0 and at 65 C, with K M = 1.2 mmol . L -1 . The esterase hydrolyzed synthetic substrates of low molecular weight (C2-C4), and among triglycerides only triacetin. Sulfhydryl group reagents and metal chelators had limited or no effect on enzyme activity; highest inhibition was observed with phenylmethylsulfonylfluoride (PMSF).