Hydrolysis of Phosphoric Acid Ester across an Enzyme Membrane

Acid phosphatase from potato was immobilized onto the surface of the external solution side of a perfluorocarboxylate ionomer membrane using a cross-linking reagent. Based on the distinct difference in membrane permeabilities to 4-nitrophenol and 4-nitrophenyl phosphate, a membrane reactor system using the immobilized enzyme has been designed for the recovery of the reaction product of enzymatic hydrolysis. To observe the recovery rate for the hydrolysis product, the flux from the external solution side to the internal solution side crossing the membrane was measured in the substrate concentration range below 1 × 10-2 mol dm-3. The recovery rate was found to obey a Michaelis-Menten type equation. The Michaelis constant for the immobilized enzyme was smaller than that for the free enzyme obtained from the kinetic properties in the bulk solution. The optimum pH value for the immobilized enzyme membrane was investigated.