EFFECTS OF SURFACTANTS ON THE STABILIZATION OF THE BOVINE LACTOPEROXIDASE ACTIVITY

Bovine lactoperoxidase (LPO) is taken as a model protein of mammalian peroxidases to investigate the activity and the stability of the enzym e in the presence of different surfactants. The cationic benzalkonium chloride (Bz) has proved efficient in preserving the enzymatic activit y for over 10 days, while the native enzyme completely lost its activi ty within 3-4 days. The presence of Bz allows the enzyme to preserve i ts secondary structure for a long time, as shown in GD spectra, and cr eates a more hydrophobic environment for the enzyme, as indicated in f luorescence studies. Moreover, this surfactant at a concentration of 0 .01% (0.3 mM) increases the lactoperoxidase activity in the first 2 h of incubation at 37 degrees C. Both hydrophobic and electrostatic inte ractions of the cationic surfactant seem to be responsible for the enz yme activation and stabilization, and this is a promising result in vi ew of industrial applications of enzymes.