The potential of O-aminopropyl amylose (APA) for the stabilization of horseradish peroxidase (POD) was comprehensively studied in this research. The addition of APA was capable of stabilizing POD against heat inactivation at neutral and acidic pH. Generally, a higher degree of substitution (DS) resulted in a better stabilizing effect. A variety of parameters were tested for the cross-link reaction of APA with POD. This cross-linking resulted in a significant stabilization of POD against thermal and pH stress at alkaline and acidic pH. The major drawback of this enzyme modification method was, that POD was inactivated to a certain extend during the oxidation step. However, long-term stability could be improved for pH 10. In comparison with the common cross-linker 1,6-diaminohexane (DAH), APA showed high potential as an enzyme cross-linker. (C) 2003 Elsevier Inc. All rights reserved.