A table-top prototype has been constructed that uses the enzyme malate dehydrogenase to recognize input signal patterns.
Output is monitored spectroscopically.
Injection along neither or both lines results in an output of 0. The enzyme in effect is used as a transform that converts the linearly inseparable exclusive-or problem into a linearly separable problem. Enzymes are molecular pattern recognizers that respond to specific features of a complex chemical milieu. This requires that the device give a 1 output in response to binary signal inputs 01 and 10 and a 0 output to 00 and 11 input patterns. The XOR operation is linearly inseparable, corresponding to the fact that input patterns cannot be separated into the output categories by a single threshold.