MODULATION OF FIREFLY LUCIFERASE BIOLUMINESCENCE AT BIOELECTROCHEMICAL INTERFACES

This paper describes a method by which the activity of an immobilized enzyme can be modulated electrochemically at an electrode. The particu lar example studied, involving the enzyme firefly luciferase being imm obilized in a gelatin film of thickness <1 mu m, provides a useful mod el system since changes in the catalytic activity can be measured inst antaneously through the natural bioluminescent emission. Using this bi ointerfacial arrangement, we have been able to demonstrate the reversi ble switching off and on of the enzyme's activity. Through a series of mechanistic studies, we have been able to determine that the biolumin escence response is modulated (on long time scales) as a consequence o f the electrochemical depletion of protons at the electrode interface resulting in a local increase in pH.