Enzymatic pattern processing

 A table-top prototype has been constructed that uses the enzyme malate dehydrogenase to recognize input signal patterns. The device is controlled by the enzyme in response to injection of Mg²⁺ used as a signaling substance. Output is monitored spectroscopically. If Mg²⁺ is injected along either of two signal lines (i.e., if the input signal pattern is 10 or 01) the device emits an output of 1. 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. Received: 3 April 2000 / Accepted in revised form: 16 June 2000