Lignin peroxidase from Phanerochaete chrysosporium. Molecular and kinetic characterization of isozymes.

Five isozymes of lignin peroxidase from Phanerochaete chrysosporium were purified and their physical, molecular and kinetic properties determined. The isozymes differ from each other in terms of their isoelectric point, molecular mass, sugar content, spectral characteristics, substrate specificity and stability. The N-terminal sequence of amino acids was different for each isozyme suggesting they are different gene products. The isozyme with the highest carbohydrate level was most sensitive to changes in environmental factors. The kinetic behaviour of the isozymes varied clearly when tert-butyl hydroperoxide instead of hydrogen peroxide was used as the oxidant. Two out of five isozymes had very similar substrate specificity. The results are discussed in relation to the role which lignin peroxidase isozymes may play in lignin biodegradation.