Purification and properties of a lipase from Penicillium expansum

Penicillum expansum DSM 1994 produces a new, inducible extracellular lipase when grown in medium containing 0.1% olive oil. Maximum activity was obtained after 4 days of incubation at 20 degrees C. The enzyme was purified 219-fold by cross-flow filtration, ammonium sulfate precipitation and hydrophobic interaction chromatography to a final specific activity of 558 U/mg. The molecular weight of the homogeneous lipase was (25 kDa) determined by gel filtration and SDS-PAGE, however, it forms active dimers and higher aggregates as observed after native PAGE. The enzyme was identified as a glycoprotein with a pI of 5.5. The N-terminal sequence shows a homology to sequences of other lipase just behind their consensus sequence. Enzyme stability was enhanced by the addition of Tween 20 and Lubrol PX. The enzyme showed a maximum activity at pH 9 at 45 degrees C and was stable at a broad pH range of 6-10. Lipase of P. expansum showed a preference for triacylglycerols, but no positional specificity.