Comparison of the enzyme kinetics and immunological properties of catalase immobilized by microencapsulation and catalase in free solution for enzyme replacement

Abstract

The enzyme kinetics and immunological properties of catalase (H 2O 2:H 2O 2 oxidoreductase, EC 1.11.1.6) immobilized by microencapsulation are studied and compared to catalase in free solution. In vitro studies show that the K m for both forms of catalase is 0.55 M. The V of the microencapsulated catalase is 0.5 mM/min while that of catalase in free solution is 2.5 mM/min. The in vivo enzyme kinetics were studied using Feinsteins's acatalasemic mice which have a hereditary deficiency in catalase. These in vivo studies show that microencapsulated catalase is as effective as the same assayed amount of catalase in free solution in reducing total body substrates in the form of exogenous perborates. After injection, microencapsulated catalase with an in vivo half-life of 4.4 days is more stable than catalase in free solution which has an in vivo half-life of 2.0 days. In vitro studies show that the enclosing membranes of semipermeable microcapsules are impermeable to beef catalase antibodies. Repeated injection of beef catalase solution into acatalasemic mice sensitized the mice to a large dose of the enzyme in solution, but not to the same dose of enzyme immobilized within semipermeable microcapsules. Injection of catalase in free solution is removed very rapidly from the circulation of acatalasemic mice immunized to catalase. Catalase in free solution was not effective in reducing total body sodium perborate levels in immunized mice, while microencapsulated catalase acted efficiently when injected into the immunized mice.