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>i.e.</i> 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.

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>i.e.</i> 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.

Hydrolytic depolymerization of corncob lignin in the view of a bio-based rigid polyurethane foam synthesis

Corncob lignin was efficiently depolymerized in an isopropanol–water mixture with NaOH as catalyst into bio-polyols with low molecular weight and suitable hydroxyl number in view of the preparation of a bio-based rigid polyurethane foam.

Energy Efficiency Analysis of PET Hydrolyzed by Different Ways of Microwave Irradiation

The effect of microwave irradiation way on hydrolytic depolymerization of poly (ethylene terephthalate) (PET) was studied at 175°C, 180°C and 185°C. Based on this study, an additional experiment that the intermittent radiation time was one tenth of total reaction time (intermittent radiation (1/10)) was conducted to research the microwave energy utilization. The results showed that the energy efficiency increased as the temperature rose. And the energy utilization of intermittent radiation (1/10) was 16.7% higher than that of the continuous radiation at 175°C.

End-Group Method for Molecular Weight Determination of PET Depolymerization under Microwave Irradiation

A series of catalysis hydrolytic depolymerization of PET catalyzed by zinc acetate, zinc sulfate, stannous oxide respectively under microwave irradiation at different temperature with time was studied, in which the microwave power was 260W, the ratio of water to PET was 10:1 and the dosage of the catalysts was 0.5% of PET. The relative number average molecular weight of the undepolymerized PET was determined by end-group method. The results show that the molecular weight of the undepolymerized PET decreases with the reaction time increasing, and tends to be stable at the end of the depolymerization reaction. Under the same time, the temperature is higher, the molecular weight is smaller. The molecular weight of the undepolymerized PET reduces most quickly with stannous oxide among the three catalysts.