Purification and general properties of a metal-insensitive lipase from Rhizopus japonicus NR 400.

Lipase [triacylglycerol lipase, EC 3.1.1.3] has been purified to homogeneity from Rhizopus japonicus NR 400 by chromatography on hydroxylapatite, octyl-Sepharose and Sephacryl S-200. It showed a molecular weight of about 30,000 by SDS-PAGE and a specific activity of 68,900 units/mg protein. The enzyme catalyzed the hydrolysis of tricapryn and tricaprylin rapidly in comparison with other triglycerides. This lipase had an optimum pH of around 5, and albumin enhanced its activity between pH 3 and 8. The composition of fatty acids liberated from linseed oil by the lipase was similar to that in the case of pancreatic lipase. The lipase activity was not affected by the addition of 1 mM metal ions or bile salts. Stimulation of the lipase activity was observed upon addition of albumin to the reaction mixture. Immunotitration experiments were also performed with antibodies raised against the purified lipase.