Purification and Characterization of a Milk-clotting Enzyme from Hericium erinaceum

Abstract

In this study, a milk-clotting enzyme was partially purified from the mycelium of Hericium erinaceum (H. erinaceum) by ammonium sulfate fractionation, ion-exchange chromatography and gel filtration. The enzyme was purified at approximately 60-fold from a crude enzyme solution with 0.3% recovery of the original activity. The partially purified enzyme was found to have a molecular weight of 36 kDa as determined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and 30 kDa by gel filtration high performance liquid chromatography. The proteolysis of κ-casein by the partially purified enzyme from H. erinaceum was studied with SDS-PAGE and reverse-phase high performance liquid chromatography. The results revealed that degradation of κ-casein occurred with the partially purified enzyme from H. erinaceum, and that it might be similar to the degradation observed with chymosin.

These results indicate that a chymosin-like protease is present in the mycelium of H. erinaceum.