Examining surface properties of cellulases to mitigate lignin adsorption

A known phenomenon that decreases the performance of cellulase cocktails is the inhibitory effect of lignin on the enzymatic hydrolysis of lignocellulosic biomass. Nonproductive adsorption of cellulases to lignin is hypothesized to be a possible source of inhibition, yet the mechanisms driving enzyme adsorption have not been elucidated. This work probes mechanisms behind the enzyme-lignin interaction by scoring enzymes according to surface properties that are hypothetically responsible for lignin binding. Quartz-Crystal Microbalance with Dissipation monitoring (QCM-D) was used to measure enzyme adsorption to lignin films. Initial biophysical measurements and structural analysis identify a surface property that correlates with the degree of adsorption in at least three enzymes. Further, the structural analysis directs mutational strategies to protein regions that are surface amino acids likely to affect lignin affinity but are far from active sites, opening the possibility of designing cellulases with similar activity as native enzymes but with decreased inhibitory binding to lignin.