Sortase-Mediated Immobilization of Candida Antarctica Lipase B (Calb) on Graphene Oxide; Comparison with Chemical Approach

In this study, Candida Antarctica lipase B (CalB) was covalently immobilized on the surface of graphene oxide (GO) nanoparticles by sortase-mediated immobilization as well as a chemical attachment approach. Sortase is a transpeptidase that provides one-step purification and targeted immobilization of CalB to the support only from a specific site on the surface thus presenting oriented immobilization of CalB. Chemical immobilization, on the other hand, is considered as a random immobilization, in which the protein can bind to the support surface from different regions of the protein surface. The applied methods produced 60% and 100% immobilization yields for oriented and random immobilization, respectively. The calculated specific activity for the derivatives obtained by the oriented and random immobilization was determined to be 0.106 and 0.085 U/mg of biocatalyst, respectively. The stabilized enzyme with the sortase-mediated approach retained approximately 80% of its initial activity at 50 °C