Characterization of the Interactions between Polyethylene Glycol and Cellulase during the Hydrolysis of Lignocellulose

Abstract

The interaction between polyethylene glycol (PEG) and the substrate has been widely examined for the purpose of using it to improve the enzymatic hydrolysis efficiency of lignocellulosic biomass. However, the knowledge about the positive effect of PEG on cellulase remains very limited and the mechanism underlying this positive effect has not been clearly elucidated. Our study found that the conversion rates of corn stover and Avicel PH101 increased to 53.8 and 86.8 %, respectively, with the pretreatment using PEG 6000 prior to hydrolysis. After incubation for 48 h, 68.2 % of the enzymatic activity was retained in the solution, whereas in the control, only 38.6 % of the enzyme activity was retained. The existence of this interaction and entropy generation was qualitatively confirmed by calorimetric titration. Moreover, entropy was identified as a reason for the hydrolytic acceleration. Additionally, hydrophobic effects and the hydrogen bonds formed between PEG and key amino acids contributed to cellulase activity enhancement. These results provide insight into the observed positive effects of PEG on cellulase function and indicate that PEG pretreatment would be beneficial to reduce enzyme load.