J. Biol. Chem., Vol. 263, Issue 3, 1195-1198, Jan, 1988
Studies on compound I formation of the lignin peroxidase from Phanerochaete chrysosporium
A Andrawis, KA Johnson and M Tien
Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802.
Ligninase, isolated from the wood-destroying fungus Phanerochaete
chrysosporium, catalyzes the oxidation of lignin and lignin-related
compounds. Ligninase reacts with H2O2 to form the classical peroxidase
intermediates Compounds I and II. We have determined the activation energy
of ligninase Compound I formation to be 5.9 kcal/mol. The effect of pH and
ionic strength on the rate of ligninase Compound I formation was studied.
In contrast to all other peroxidases, no pH effect was observed. This is
despite homology of active-site amino acids residues (Tien, M., and Tu,
C.-P. D. (1987) Nature 326, 520-523) which are proposed to affect the pH
profile of Compound I formation. Ligninase Compound I formation can also be
supported by organic peroxides. The second-order rate constants with the
organic peroxides are lower, suggesting that H2O2 is the preferred
substrate.