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

An intracellular esterase from Propionibacterium freudenreichii ssp. freude nreichii ITG 14 was purified by anion exchange and gel filtration chromatog raphy. The enzyme had a molecular weight of 37 400 g.mol(-1) as determined by gel filtration chromatography, with an optimum activity on a-naphthyl-ac etate at pH 6.0 and at 65 degreesC, with K-M = 1.2 mmol.L-1. The esterase h ydrolyzed synthetic substrates of low molecular weight (C2-C4), and among t riglycerides only triacetin. Sulfhydryl group reagents and metal chelators had limited or no effect on enzyme activity; highest inhibition was observe d with phenyl methylsulfonylfluoride (PMSF).