Purification and characterisation of an alkaliphilic esterase from a culinary medicinal mushroom, Sparassis crispa

In this study, we found that the fruiting body of the medicinal and edible mushroom Sparassis crispa produces an alkaliphilic esterase. The substrate specificity of this esterase was high for a p-nitrophenyl acetate substrate. The S. crispa esterase was purified using ammonium sulphate precipitation, anion exchange and gel filtration chromatography. The recovery and purification yields of the enzyme were 15–17% and 70–73 folds from six different strains of S. crispa, respectively. The molecular weight of the purified enzyme was approximately 60 kDa, as determined by SDS–PAGE. A zymogram analysis using a tributyrin substrate revealed that this enzyme is an esterase. The optimum pH and temperature were 8.0 and 50 °C, respectively. The pH and temperature stability profiles show that this enzyme is more stable under alkaline conditions and at 30–40 °C. Km and Vmax for this esterase enzyme acting on p-nitrophenyl acetate were 0.2 mM and 0.5 U/mg proteins, respectively.