The effect of protein concentration on adsorption of β-glucosidases to lignin for Cellic® CTec2 (CC2) and Novozym 188 (NZ188). (a) Relative amount of free β-glucosidase activity and (b) stain-free SDS-PAGE. Total β-glucosidase activity 500 nkat/mL. Protein concentrations in experiment: Cellic CTec2, 2.1 mg/mL; Cellic CTec2 + BSA, 28.0 mg/mL; and Novozym 188, 28.0 mg/mL. The activities are relative to the controls without added substrate (and BSA) for each enzyme. BSA, bovine serum albumin.