Controlling the Reactivity of Enzymes in Mechanochemistry: Inert Surfaces Protect β-Glucosidase Activity During Ball Milling

Although cellulose has been identified as the foremost candidate for the replacement of fossil fuels, its recalcitrant nature prevents the full deployment of technologies based on its saccharification. We recently reported a possible strategy to resolve this conundrum: using cellulases under “RAging” - a solvent-free process that utilizes enzymes under mechanochemical conditions - to achieve fast, efficient hydrolytic depolymerization of cellulosic materials into glucose. β-Glucosidases catalyze the last and often limiting step of this process, i.e. the formation of glucose from cellobiose. Here, we reveal the high sensitivity of β-glucosidases to ball milling, as well as an unexpected stabilization effect of inert surfaces, enabling the protection of β-glucosidases under mechanochemical treatment. This approach provides an unexpected strategy to control the reactivity of enzymes under mechanochemical conditions. Finally, our results also provide the very first demonstration of enzymatic equilibrium under mechanochemical conditions.