LIGNIN PEROXIDASE FROM CHRYSONILIA-SITOPHILA - HEAT-DENATURATION KINETICS AND PH STABILITY

Many practical applications utilizing lignin peroxidases from Chrysonilia sitophila (TFB-27441 strain) have been proposed. However, more information regarding the stability of these enzymes was required to design and develop these technologies. Heat- and pH-denaturation studies were conducted on purified lignin peroxidase and on crude culture of lignin peroxidase from C. sitophila. The culture produced in a 15-l bioreactor with Fries medium was utilized to obtain purified lignin peroxidases. LIG-I, LIG-II, and LIG-III were tested in the range 28-50-degrees-C, and LIG-III was found to be the most stable in the temperature range tested. The observed k(D) values at 28, 35, and 50-degrees-C were 0.058, 0.095, and 0.111 h-1, respectively. Increasing the LIG-III concentration by 2.3-fold increased thermal stability by around twofold. The heat-denaturation kinetics under these conditions for all lignin peroxidases and for the crude culture were first-order. LIG-I and LIG-II appeared as the most representative enzymes in the crude culture, since similar k(D) values were obtained. The pH stability showed the same trends.