Invertase was immobilized onto the granular dimer acid-co-alkyl polyamine after activation with carbodiimide. The K-m value for immobilized enzyme (53.6 mM) was much greater than that of the free enzyme (20.6 mM). V-max values were 6.44x10(-5) mol dm(-3) min(-1) and 5.45x10(-5) mol dm(-3) min(-1) for free and bound, respectively. The optimal pH values for free and covalently bonded enzymes were 4.56 and 5.50, respectively. The optimum temperature for both free and covalent invertase was 55 degrees C. The enzyme activities, after storage for 1 month, were found to be 21.0 and 99.0% of the initial activity values for free and covalently bonded, respectively. The immobilized enzyme that was used 50 times in 5 days in repeated batch experiments showed 100% of its original activity. (C) 2000 Elsevier Science Ltd. All rights reserved.