Immobilization of digitoxin 12β-hydroxylase, a cytochrome P-450-dependent enzyme from cell cultures of Digitalis lanata EHRH.

Attempts were made to immobilize digitoxin 12β-hydroxylase, a membrane-bound, cytochrome P-450-dependent monooxygenase from cell cultures of Digitalis lanata. The optimum procedure was the entrapment of microsomes in 2% alginate by crosslinking the polysaccharide chains with CaCl2. After the immobilization of the enzyme about 70% of its activity was retained. The kinetic data such as the pH optimum and the optimum substrate concentrations were identical for the immobilized enzyme and freely suspended microsomes. Using β-methyldigitoxin as a substrate enzyme activity could be observed for more than 20 h. A continuous flow system for immobilized digitoxin 12β-hydroxylase is described.