Investigations of stabilities,pH, and temperature profiles and kinetic parameters of glucoamylase immobilized on plastic supports

The covalent immobilization of glucoamylase on new epoxide-, isocyanate-, acid chloride-, and carboxylic acid-activated plastic supports shows the viability of such supports for immobilizing enzymes (especially those reacting with 1,6-diaminohexane and glutaraldehyde) for producing side arms. The operational stability of immobilized glucoamylase could be extended by crosslinking the enzyme, by increasing the substrate concentration, or by extending the support’s side arm. The pH curves for the immobilized enzyme were in general not found to be shifted from the pH optimum of the soluble enzyme. However, the immobilized enzyme’s temperature activity profiles were shifted to a lower temperature range when compared to the soluble enzyme. The immobilized glucoamylase Michaelis constants increased, and the maximum rates and specific activities decreased with respect to the soluble enzyme kinetic parameters.