An extracellular lipase, which is produced by theNeurospora sp. TT-241 strain, grown on wheat bran at 30°C for 4 d, was purified 370-fold with an overall yield of 16%. The molecular weight was determined to be 55 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimal pH at 30°C and optimal temperature at pH 6.5 were 7 and 45°C, respectively. The lipase was stable in the pH range of 5 to 8, and it was temperature-sensitive. It was active on a wide range of natural substrates of either vegetable or animal origins and towardp-nitrophenyl esters, greatly favoring those containing C4 acyl groups. It cleaved all of the ester bonds of triolein; however, the 1- or 3-ester bond was the preferred target. A complete inhibition by diisopropyl fluorophosphate suggested the presence of a serine residue at the active site. Partial inhibition was shown by either Hg2+ or chloramine T. Enzyme activity persisted in nonionic surfactants, a water-miscible solvent (dimethylsulfoxide), and a water-immiscible solvent (hexane).
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