The influence of metal ions on endopolygalacturonase from Aspergillus niger 71 soluble and immobilized by NH2 or COOH groups

Abstract Purified endopolygalacturonase (EC 3.2.1.15) from Aspergillus niger 71 was immobilized covalently by NH 2 or COOH groups to the supports. The influence of Ca, Mg, Mn, Zn, Cu as well as of Pb, Hg and Cd ions in concentrations from 0.1 to 1.2 mM on the soluble and immobilized enzyme was shown. Endopolygalacturonase activity after immobilization is stabilized even in the presence of Pb, Hg and Cd ions. When this enzyme was immobilized by COOH groups with the support, the metal ions used decreased its activity more effectively than that of the soluble form of this enzyme. In contrast, when endopolygalacturonase was immobilized by NH 2 groups, the activity of this enzyme was not only stabilized, but Cu, Mg and Cd ions also caused a 40 to 60% increase in the enzyme activity.