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Highlights in Chemical Science

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Logic gate operations performed by enzymes

17 March 2006

Enzymes can mimic a computational process involving a system of logic gates, say scientists in Israel. 

Itamar Willner and colleagues at The Hebrew University of Jerusalem used a simple system of two coupled enzymes (glucose dehydrogenase and horseradish peroxidase) as "AND" and "InhibAND" logic gates - the elementary building blocks of digital circuits. 

Using glucose and hydrogen peroxide as gate inputs, logic gate operations were performed in parallel, generating NADH (the reduced form of nicotinamide adenine dinucleotide) and gluconic acids as output signals. These outputs gave a simultaneous readout of the gate functions.


                      Coupled enzymes


The diversity of enzymes that can be used means that many different logic gates could be created, said Willner, leading to computational systems of enhanced complexity. Enzymes have a significant advantage over their molecular predecessors as there is no need to synthesise complex molecular structures. The chair of organic chemistry at Queen's University Belfast, A P de Silva, agrees. 'The biggest advantage is the availability of many natural enzyme cascades,' said de Silva. 

Willner and his team plan to construct biomolecule-based systems that perform parallel and sequential logic gate operations, leading to arithmetic and computational functions. 'We wish to demonstrate with such "slow" biomolecule-based computers that new functions, which cannot be reached by regular computers, may be realised,' said Willner.

He added that, in the future, biomolecule-based computers could be implanted into organs and used to follow metabolic pathways or drug delivery.

Elinor L Richards


R Baron, O Lioubashevski, E Katz, T Niazov and I Willner, Org. Biomol. Chem., 2006, 1249 (DOI: 10.1039/b518205k)