Metal chelate-epoxy bifunctional membranes for selective adsorption and covalent immobilization of a His-tagged protein

The preparation and application of metal chelate-epoxy bifunctional membranes for the selective adsorption and covalent immobilization of His-tagged protein switch RG13 were shown in this study. By controlling the concentration of iminodiacetic acid (IDA) and reaction time during the conjugation of IDA on to the epichlorohydrin-activated regenerated cellulose membrane, 5 metal chelate-epoxy bifunctional membranes, with degrees of IDA conjugation in the range of 20%-81%, were prepared. The bifunctional membrane with an IDA conjugation degree of 30%, designated as BFM30, exhibited a sound adsorption capacity of 0.203 mg/cm2 with a relatively high content of epoxy groups for covalent immobilization, were selected. The concomitant selective adsorption and covalent immobilization of the Histagged RG13 with BFM30 were carried out by 2-h incubation for protein adsorption and subsequent 16-h incubation for covalent immobilization after the removal of undesired proteins with wash buffer, giving an immobilization yield of 63% and a global activity yield 40%. The RG13 immobilized on the metal chelate-epoxy bifunctional membrane exhibited superior operational stability in a repeated batch process, retaining 94% of its initial activity after 20 cycles. The employment of the bifunctional membranes could significant facilitate enzyme immobilization processes by eliminating the need for prior protein purification.

Automated summary

This study demonstrated the preparation and application of metal chelate-epoxy bifunctional membranes for selective adsorption and covalent immobilization of His-tagged protein switch RG13. The BFM30 membrane showed the best performance in terms of protein immobilization and operational stability. The use of bifunctional membranes can simplify the enzyme immobilization process.