INACTIVATION OF CELL-WALL ACIDIC PEROXIDASE ISOENZYMES DURING THE OXIDATION OF CONIFERYL ALCOHOL IN LUPINUS

Lignification of the cell wall of primary and secondary xylem vessels in lupin (Lupinus albus cv Multolupa) hypocotyls is associated first w ith an increase in the level of cell wall peroxidase activity, due mai nly to the specific expression of the isoenzyme A(1), followed by a de crease in the activity, caused by its disappearance. Since during the oxidation of coniferyl alcohol by cell wall acidic peroxidases from lu pin hypocotyls a specific inactivation of peroxidase isoenzyme A(1) ta kes place, this process is apparently responsible for the loss of pero xidase activity in lignified lupin cell walls.