Abstract

An extracellular lipase from Psedoxanthomonas sp. was purified 47.3 folds with an overall yield of 27% through purification procedure of acetone precipitation, ion exchange and gel filtration chromatography. Protein precipitation using acetone fractionation showed that the enzyme was precipitated at the fraction of 0 to 40%. Further purification of the enzyme by ion exchange followed by gel filtration chromatography showed that there were two types of lipases with similar molecular size at around 50 kDa. Characterization of optimum pH, temperature, and substrate specificity were carried out against the isolated lipase. Lip1 showed specific substrate preferences towards p-nitro phenyl myristate meanwhile Lip2 exhibited hydrolytic activity towards short and medium acyl chain of the substrate. Further analysis of both enzyme activities on variation of pH and temperature showed that the optimum pH and temperature for Lip1 were at pH 10.0 and 70°C, respectively while pH 8.0 and 50°C were the optimum pH and temperature for Lip2 respectively. Lyophilized lipase isolated from acetone fraction showed lipolytic activity under variation of methanol concentration up to 30%.

Key words: Pseudoxanthomonas lipase, ion exchange chromatography, gel filtration chromatography.