Logical Nano-Computation in Enzymatic Reaction Networks

We propose a way to implement logical operations at the nanoscale by means of enzymatic reaction networks such as kinase-phosphatase networks. For this we suggest and analyze a small recurrent enzymatic reaction network with only four molecule species which contains a positive and a double negative feedback loop. The system is shown to have bistable regimes, the phase boundaries of which are analytically determined. We show that, by adjustment of the total concentrations of the species relative to the range of concentrations of the input substances, it is possible to flexibly implement logical AND, OR, and NOT gates with variable input sensitivity and output dynamic range. Finally, a realistic kinase-phosphatase implementation of the circuit is provided