Fig. 1.

Activation model of EcPOX. At low pyruvate concentrations, the enzyme is located in the cytosol and exhibits a low basal activity and low substrate affinity. High pyruvate concentrations cause reduction of the flavin and a structural rearrangement that exposes the C terminus as a high affinity lipid binding site. Binding of the reduced enzyme to the membrane (in vivo) or mild proteolytic digestion (in vitro) lock in the activated conformation with elevated activity and substrate affinity (17).