Studies on compound I formation of the lignin peroxidase from Phanerochaete chrysosporium.
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.
Andrawis
A
A
Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802.
Johnson
K A
KA
Tien
M
M
D000595:Amino Acid Sequence; D002912:Chrysosporium / Q000201:enzymology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D003904:Mitosporic Fungi / Q000201:enzymology*; D009566:Nitrates / Q000378:metabolism; D009994:Osmolar Concentration; D010105:Oxygenases / Q000378:metabolism*; D010544:Peroxidases; D013054:Spectrophotometry, Atomic
D009566:Nitrates; D006861:Hydrogen Peroxide; D010544:Peroxidases; C042858:lignin peroxidase; D010105:Oxygenases; C044391:ligninase