Kinetics of optical control of enzyme activity with photoswitchable inhibitors

This paper presents theoretical and simulation studies on controlling enzymatic reactions with photoswitchable inhibitors. It is found that the maximum attainable switching ratio (ratio of the steady state rates of product formation in the “on” and the “off” state) of a photoswitchable inhibitor is dependent on its photoswitching factor (ratio of the equilibrium constants of the photostationary states under the “off” and the “on” illuminations). Attachment of multiple photoswitchable groups to an inhibitor molecule increases the theoretically attainable switching ratio. The affinity of the enzyme for the substrate and the inhibitor is the rate-limiting factor of the switching between active and inactive states. Use of inhibitors with high enzyme affinity and photoswitchable groups with high photoswitching factor would provide high switching ratio. These results may help to design better systems for optical control of biochemical processes.