Following the Energy: the Hopfield Barrier as an Organising Principle

Jeremy Gunawardena (June 25, 2019)

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Hopfield's classic paper on kinetic proofreading conceals an important observation. If a biochemical system implementing a given information processing task is operating at thermodynamic equilibrium, there is an upper limit to how well it can perform that task; the only way to exceed this limit is to maintain the system away from equilibrium by expending energy. We call the limit the Hopfield barrier for the task in question. We will discuss some examples and suggest that identifying Hopfield barriers for the various tasks which biological cells undertake offers a systematic way to rise above molecular complexity and discern the underlying Rules of Life.