Isolation and characterization of an extracellular lipase from the conidia of Neurospora cvassa

Abstract

A triacylglycerol lipase (EC 3.1.1.3) from the conidia of Neurospora crassa was purified and characterized. The enzyme was purified by Sephadex G-100 column chromatography. Homogeneity was checked by PAGE, and isoelectric focusing gave a single band corresponding to a pI of 6.4. The enzyme had an apparent M_r 54000≥1000 as determined by gel filtration. SDS-PAGE gave a single band of M_r 27000, suggesting the presence of two identical subunits. This lipase preferred triglycerides with C₁₆- and C₁₈-fatty acyl chains. It cleaved only the primary groups of triglycerides. The lipase also exhibited a marked preference for substrates containing endogenously occurring fatty acids and so may prove useful in detailed studies on the physiological relevance of fatty acyl specificity of lipases. The enzyme was not affected by detergents, or thiol-binding agents. Modification of free amino groups caused 90% inhibition, suggesting a role of these groups in the maintenance of lipase activity.