Abstract
Background: Bovine serum albumin (BSA), polyethylene glycol (PEG) and lignosulfonate (LS) have been extensively employed as synergistic agents in lignocellulose saccharification, albeit it has not been fully understood how they interact with enzymes from the perspectives of molecular interactions. Herein, we attempted to unveil the promotion mechanisms of BSA, PEG and LS for lignocellulose saccharification from the perspective of their respective interaction with cellulase using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Surface Plasmon Resonance (SPR), and Small Angle X-ray Scattering (SAXS) to investigate their respective interaction and the complex formation. In the meanwhile, we compared the effects of adding these additives into the enzymatic hydrolysis of pure cellulose (Avicel) and green liquor-pretreated lignocellulose (GL).Results: The results showed that BSA and LS could bind to cellulase to form complexes, whereas PEG did not. However, PEG had a high affinity to lignin or lignin derivatives. In term for Avicel and GL substrates, the results showed that BSA and PEG promoted the enzymatic hydrolysis of both substrates, while LS had a promoting effect for GL only and inhibited some extent for Avicel. Conclusions: This study showed that synergistic agents of LS, BSA, and PEG have different interaction modes with cellulase. BSA and LS form complexes with cellulase and the formed complexes prevent from nonproductive binding by residue lignin; whereas PEG prevents from nonproductive binding by forming a thin layer on residue lignin which actually serve as steric hindrance. This investigation will help us to understand the sophisticated interactions among the components in the complicated enzymatic system, especially the interactions between enzymes and synergistic agents. It will be helpful in the design and utilization of synergistic additives in the lignocellulose biorefinery process as well.
Comparison of the Interaction Modes Between Cellulase and Bovine Serum Albumin /Lignosulfonate /Polyethylene Glycol in Promoting Lignocellulose Saccharification
