Abstract
The last step of lignification is polymerization of monolignols by peroxidases. In the polymerization process monolignol radicals should couple to the pre-polymer radicals to produce lignin macromolecule. The detail mechanisms of peroxidase catalytic reaction on the polymerization of lignin is still uncertain, because it has not been clear whether peroxidase can oxidize pre-polymer through a direct interaction or through radical mediation. We have studied the catalytic efficiency of oxidative polymerization by a specific peroxidase or radical mediation from monolignol radicals. The coniferyl alcohol radical transferred to sinapyl alcohol very fast, but hardly transferred to sinapyl alcohol polymer. On the other hand, CWPO-C, which was isolated from the cell wall of poplar ( Populus alba L.) callus, has high catalytic ability for the oxidation of sinapyl alcohol polymer. The western analysis using polyclonal antiserum raised against CWPO-C showed that this peroxidase locates in the cell walls of poplar developing xylem.
