The addition of polyethyleneimine with a molecular weight of 2000 to chloroperoxidase from Caldariomyces fumago dramatically improved the stability of the enzyme towards peroxide dependent inactivation. The rate constant for the H 2 O 2 -dependent inactivation of chloroperoxidase decreased from 0.0016s -1 to 1.1 * 10 -5 s -1 in the presence of 1% polyethyleneimine. The stabilising effect towards tert-butyl hydroperoxide was even more impressive. The half-life of the chloroperoxidase when exposed to a solution of 40 mM tert-butyl hydroperoxide increased from 3.2 minutes to ≥ 70 hours in presence of 0.1% polyethyleneimine.
