Hyperactivation and thermostabilization of Phanerochaete chrysosporium lignin peroxidase by immobilization in xerogels

This is a continuation of our previous paper on production of lignin peroxidase (LiP) by Phanerochaete chrysosporium in solid substrate fermentation (SSF) medium of corncobs. The enzyme was purified by ammonium sulphate precipitation and ion-exchange fast protein liquid chromatography. Maximum yield of LiP was 13.7 U/gds (units per gram dry substrate) after 5 days of SSF with 70% moisture and 20% (v/w) inoculum. The approximate molecular mass of purified LiP, estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, was 38 kDa. The pH and temperature optima for the LiP were 4 and 40 degrees C, respectively. Immobilization of LiP in hydrophobic xerogels caused hyperactivation of LiP and enhanced its thermostability properties. The K-M and V-max values for immobilized LiP were 10.56 mg/ml and 16.67 mu mol/min (120.49 U/mg of protein) as compared to 13 mg/ml and 11.76 mu mol/min (85 U/mg of protein), respectively, for free LiP using veratryl alcohol as substrate.