Purification and characterization of an extracellular lipase from Penicillium candidum

Penicillium candidum produces and secretes a single extracellular lipase wi th a monomer molecular weight of 29 kDa. However, this enzyme forms dimers and higher molecular weight aggregates under nondenaturing conditions. The lipase from P, candidum was purified 37-fold using Octyl-Sepharose CL-4B an d DEAE-Sephadex columns. The optimal assay conditions for lipase activity w ere 35 degreesC and pH 9. The lipase was stable in the pH range of 5-6 with a pi of 5.5, but rapid loss of the enzyme activity was observed above 25 d egreesC. Tributyrin was found to be the best substrate for the P. candidum lipase, among those tested. Metal ions such as Fe2+ and Cu2+ inhibited enzy matic activity and only Ca2+ was able to slightly enhance lipase activity. Ionic detergents inhibited the activity of the enzyme, whereas nonionic det ergents stimulated lipase activity.