DEACTIVATION KINETICS OF LIGNIN PEROXIDASE FROM PHANEROCHAETE-CHRYSOSPORIUM

Crude extracellular enzyme from Phanerochaete chrysosporium BKM-F-1767 (ATCC 24725) was used for kinetics and deactivation studies. The kinet ics of lignin peroxidase in the crude enzyme was fitted to a ping-pong -bi-bi model with competitive substrate (hydrogen peroxide) inhibition . Several divalent metal salts (MnCl2, MnSO4, MgCl2, and CaCl2) enhanc ed LiP activity at low concentrations (<2 mm) but inhibited at high co ncentrations (>2.5 mm). Deactivation kinetic models from series-type d eactivation mechanisms correlated well with the experimental data for peroxide-dependent and pH-dependent deactivation. UV/visible spectral changes during crude enzyme deactivation in the presence of peroxide s upported the series deactivation mechanism. Strategies to enhance lign in peroxidase stability are suggested.