Partial purification and characterization of a triacylglycerol lipase from rat liver cytosol

Abstract

A triacylglycerol lipase (EC 3.1.1.3) was purified about 60-fold from rat liver cytosol by delipidation with acetone and ethyl ether, hydroxyapatite and Sephadex G-100 column chromatographies and isoelectrofocusing electrophoresis. The partially purified enzyme had a molecular weight of approximately 42 000 and an isoelectric point of 7.2. The K m for trioleylglycerol was 0.33 mM and the pH optimum was around 8.0. The activity of the enzyme was not dependent on serum lipoproteins, but was stimulated about 2-fold by several proteins such as serum albumin, lipoproteins, γ-globulin and ovalbumin. The lipase hydrolyzed trioleylglycerol to oleic acid and glycerol. NaCl had no effect on the enzymatic activity. Some physical and kinetic properties of the partially purified lipid-free lipase were different from those of crude non-delipidated lipase and also from those of a neutral triacylglycerol lipase which was recently purified partially from pig liver cytosol (Ledford, J.H. and Alaupovic, P. (1975) Biochim. Biophys. Acta 398, 132–148).