Investigating lignin from Canna edulis ker residues induced activation of α-amylase: Kinetics, interaction, and molecular docking.

The lignin isolated from C. edulis ker residues showed a significant activating effect on alpha-amylase. Further studies revealed that the isolated lignin formed a 1:1 complex with alpha-amylase through hydrogen bonding and quenched fluorescence of alpha-amylase with a static quenching procedure. Binding with lignin led to conformational and granular size changes of alpha-amylase. Two-dimensional nuclear Overhauser spectroscopy (2D-NOESY) spectra suggested that -OH in G units and beta-O-4 structure were the major binding sites of lignin on the alpha-amylase molecule. Molecular docking studies indicated that the binding residue on alpha-amylase for lignin was not the same as for chloride ions, and the major binding force was hydrogen bonding. Furthermore, the docking results also showed the structural change of lignin induced by alpha-amylase. Thus, this work provided a new insight into the interaction between lignin from Canna edulis ker residues and alpha-amylase, which may be beneficial to apply lignin in the food industry.