The immobilized mercuric reductase covalently coupled to porous glass was prepared and its properties were investigated. Mercuric reductase immobilized on arylamino and carboxyl derivatives exhibited high relative activities about 20-30% compared with soluble enzymes. The optimum pH of mercuric reductase immobilized on these derivatives was 7.5, slightly higher than that of soluble state (7.0-7.2). The stability of mercuric reductase increased with immobilization onto arylamino derivative and the immobilized enzyme maintained at 30°C for 29 days showed 80-90% of initial activity. As the application of immobilized enzyme, mercuric ion sensor was prepared and it was found that mercuric ion higher than 0.5μM was detectable with this sensor.
