Deoxyribozyme (DNAzyme) carrying peroxidase activity was immobilized on two types of particles and the enzymatic activity was measured. The DNA recognizing porphyrin were prepared according to Travascio et al. ([1998] Chem Biol 5:505 - 517) and the interactions with hemin were investigated by ultraviolet absorbance and circular dichroism spectroscopies. The DNA interacted with hemin and significant conformational change was induced by the interaction. Therefore, the end of this DNA was modified with a thiol group and it was immobilized on thick containing polysaccharide beads or on gold particles. The DNA immobilized on the gold particle showed activity catalyzing the peroxidation reaction. No significant reduction of activity was observed even after immobilization. The immobilized DNAzyme could be repeatedly utilized without significant loss of activity. In addition, heat treatment did not reduce the activity, although a protein enzyme, horseradish peroxidase, lost its activity after the heat treatment. The repertoire of DNAzyme is still currently limited. However, in the future the utilization of DNAzyme in the field of biotechnology will be important with the increase of discoveries of new functional DNAzymes. (C) 2004 Wiley Periodicals.