Rational screening and mechanistic elucidation of surfactants for mitigating phenolic inhibition in lignocellulose enzymatic hydrolysis: Combining experimental and computational approaches

Lignin-derived phenolic compounds pose a critical bottleneck in the sustainable enzymatic hydrolysis of lignocellulose by causing severe enzyme inhibition. While surfactants can significantly alleviate this inhibition, their structure-function relationships and underlying molecular mechanisms remain unclear. In this study, the mitigating effects of various surfactants were quantitatively characterized, revealing that hydrophobicity, hydrogen bonding ability, and electrophilicity are the key structural descriptors for their efficacy. Experimental analysis confirmed that selected surfactants significantly mitigated phenolic-induced enzyme deactivation and precipitation. Circular dichroism spectroscopy further revealed that surfactants effectively restored the secondary structure (specifically α-helix content) and stabilized the enzyme conformation against phenolic denaturation. Molecular docking simulations demonstrated that surfactants preferentially bind within the catalytic tunnel of cellulase with stronger affinities (from –20.08 to –29.71 kJ/mol) compared to phenolics, driven by hydrogen bond anchoring reinforced by extensive hydrophobic and π-π stacking interactions with key tunnel residues. Collectively, these findings support a competitive stabilization mechanism, providing new insights into the surfactant-mediated protection of cellulase, facilitating more efficient lignocellulose enzymatic hydrolysis.