Electric field control of lipase membrane activity

Lipase (EC 3.1.1.3., from Pseudomonas sp.) was entrapped in collagen membrane containing liquid crystal (4-methoxybenzilidene-4'-n-butylaniline). The activity of the lipase-liquid crystal membrane at an applied voltage of 4 V was 3.4 compared to a membrane tested without imposition of an external electric field. A linear relationship was observed between the activity of the lipase-liquid crystal membrane and the current. The apparent Michaelis constant (K'm) of the lipase-liquid crystal membrane under electric field was identical to that of the membrane under ordinary condition. Activation of the lipase-liquid crystal membrane was observed repeatedly, i.e., activation in the presence of an electric field and reversion to a basal level upon removal of the field occurred cyclically. Activity control of immobilized enzymes is desirable for switching devices of a bioreactor. Possible mechanisms of the lipase activation by electric field are discussed.