S. Granick

Catalytic Enzymes as Active Matter

Pioneering experiments of Ayusman Sen and coworkers challenged the traditional view that enzyme kinetics is only a matter of catalyzing chemical reactions; they show that catalysis enhances enzyme mobility. This is significant to programming spatio-temporal patterns of molecular response to chemical stimulus. This talk will report that the enhanced diffusivity of enzymes is a “run-and-tumble” process analogous to that performed by swimming microorganisms, executed in this situation by molecules that lack the decision-making machinery of microorganisms. One consequence is that enzymes migrate in the direction of lesser reactant concentration when they turn over substrate; they display “anti-chemotaxis.” This run-and-tumble process offers the possible biological function to homogenize product concentration, which could be significant in situations when the reactant concentration varies from spot to spot. Attempts will be made to place these and our related recent findings in the context of larger puzzles in the active matter intellectual community.