Molecular computing: the lock-key paradigm

M. Conrad
1992 Computer  
The powerful information-processing capabilities of biological systems derive from molecular mechanisms unique to carbon polymers. This article discusses how these mechanisms can combine to yield networks that perform useful computational functions. M olecular computing as a technological field is in an early -but rapidstage of development. Primitive prototypes are beginning to appear. The more elaborate designs are paper constructions linking processes that have an isolated laboratory
more » ... . The computing concepts that fit most naturally to molecular interactions are radically different from and complementary to those that fit to existing electronic machines. Hybrid systems that combine conventional and biomolecular technologies should be able to exploit this domain complementarity and obtain powerful computational synergies. Looking in the opposite direction. working up new models of computation specifically suited to biomolecular materials may well have a salubrious impact on the understanding of biological computation itself. Molecular computers are natural or artificial systems in which macromolecules individually mediate critical information-processing functions. Biological organisms are the naturally occurring examples. Their information-processing virtuosity traces ultimately to the fact that macromolecules, most notably proteins, can recognize specific molecular objects in their environment in a manner that uses shape and depends sensitively on physiochemical context. What are the ultimate capabilities of this shape-based mode of computing? What conceptual and technological implications might this mode have? This article addresses these issues, first by introducing some basic principles and then by considering some ways that they might combine to yield new approaches to information technology. The lock-key model Electronic switches -whether household light switches. vacuum tubes, or transistors -are three-terminal devices comprising a source of electrons, a sink for electrons, and a control over their flow. A potential applied to the control terminal triggers the flow by inducing a slight shift in the concentration of electrons (or holes) away from equilibrium. Silicon is well-suited for this purpose because (in bulk) it can undergo a transition from an insulating to a conducting (metal-like) state. The switching property derives from donor and acceptor impurities that vary
doi:10.1109/2.166400 fatcat:hogtx7ykerep5av7q3wxgn634u