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Given optimum conditions, does an enzyme have a set number of catalytic cycles it can perform? Hanson et al., working in the field of synthetic biology, addressed this question by attempting to replicate or, in some cases, even better existing cellular machinery using engineering principles and emerging methodologies.

During manufacturing processes, machined components are optimised to account for failure of parts and the finite properties of materials. In a similar vein, proteins too are perhaps liable to build up accumulative deterioration from chemical insults, such as oxidation. However, the in vivo attrition rate of cellular enzymes due to cumulative damage is unrecorded.

This work shows that, unlike manufactured items, enzymes do not experience ‘progressive degradation’. Instead, enzymes are liable to instant failure as a result of random catalytic misfire or chemical attack. This suggests enzyme inactivation is more stochastic, although it also follows that the longer an enzyme is around, the more likely it is to experience a random failure event.

Using a series of powerful experiments, the study proposes calculating an enzyme’s lifespan using a ‘catalytic cycles until replacement’ measure. This work shows that it is possible to anticipate an enzyme’s functional ‘life span’, just as could be calculated for a component of a car engine. Using these data, synthetic biologists are able to calculate an enzyme’s inherent performance, designing and generating improved versions that can outlast their biological equivalent.

Read the full article in Proceedings of the National Academy of Sciences of the USA 118 e2023348118