IONIC ADSORPTION OF CATALASE ON BIOSKIN - KINETIC AND ULTRASTRUCTURALSTUDIES

Bioskin is a natural polymer produced by Acetobacter xylinum and sever al yeasts in culture. It contains glucosamine and N-acetyl galactosami ne which promote ionic adsorption of catalase at the adequate pH value . High values of ionic strength are required to enzyme desorption. Ads orption of catalase on bioskin fibers has been visualized by scanning electron microscopy associated to a dispersion X-ray analyzer. At low enzyme density, the affinity of the immobilized catalase for hydrogen peroxide was 30% lower than that of the free enzyme. This affinity dec reased dramatically at higher density of immobilized enzyme and could not be increased by agitation of the enzyme reaction mixture. Immobili zed catalase retains about 70% of its initial activity after 16 d stor age, whereas soluble enzyme is completely inactivated after 3 d at roo m temperature. The haeme group of catalase is not protected after immo bilization since it is accessible to both EDTA and phloroglucinol, che lating agents which inactivate catalase by removing the iron atom from the haeme group.