Immobilization of a Mesophilic Lipase on Graphene Oxide: Stability, Activity, and Reusability Insights

Catalyst-mediated bioprocessing at an industrial scale is dependent on the sustained stability and activity of the biocatalyst. Here, we demonstrate that strategy employed to increase the stability and activity of a mesophilic lipase immobilized on graphene oxide (GO). The protein adsorption capacity of GO is much higher than of other large surface area carbonaceous materials. Its structure and physicochemical properties are reported beneficial for enzymatic activity modifications. A purified lipase from Brevibacillus borstelensis NLIP05 immobilized on GO showed remarkable increase in thermostability (at 95°C) over a broad alkaline pH range (pH 7-12) compared to the free enzyme. Thermodynamic analysis of the GO-lip showed decreases in K_m and activation energy (E_a) with increased V_max and deactivation energy (E_d) at both 45 and 95°C. The decrease in decay constant (k) coupled with the increase in t_1/2 value with temperature increase were salient features of the GO-lip system. This implies that GO-based immobilization conferred structural stability to the enzyme at higher temperature indicating chaperone like activity. Our findings support suitability of immobilized lipase on GO nanosupport for possible production of value-added materials with varied biological applications in the form of active pharmaceutical substances, synthetic building blocks, and effective synthesis of surfactants. The enhanced stability and activity of lipase indicate major application of GO on an industrial scale.