Effect of delignification on the adsorption of loofah sponge-based immobilized metal affinity chromatography adsorbent for His-tagged trehalose synthase.

The effect of delignification on the adsorption capacity of loofah sponge-based immobilized metal affinity chromatography adsorbents was investigated with recombinant His-tagged trehalose synthase as the model protein. Pretreatments with [EMIM][Ac] ionic liquid at 80 °C for 5 h and with sodium chlorite/acetic acid at 80 °C for 2 h were found effective for the removal of lignin, leading to a loss in biomass of 15.7% and 25.2%, respectively. Upon delignification, the metal chelating capacities of the loofah sponge-based adsorbents prepared with 5-h ionic liquid pretreatment (712 ± 82 μmole Cu(II)/g) and with 2-h sodium chlorite/acetic acid pretreatment (1012 ± 18 μmole Cu(II)/g) were 38% and 97% higher than that of the control (514 ± 55 μmole Cu(II)/g), adsorbent prepared with untreated loofah sponge, respectively. Results of protein adsorption study indicated that the Co(II)-loaded adsorbent prepared with 2-h sodium chlorite/acetic acid pretreatment exhibited the highest adsorption capacity and selectivity for the recombinant His-tagged trehalose synthase, giving a purification product with a specific activity of 7.62 U/mg protein. The predicted maximum adsorption capacity of the delignified loofah sponge-based adsorbent, 2.04 ± 0.14 mg/g, was 73% higher than that of the control.