Thermostability, pH stability and dye degrading activity of a bacterial laccase are enhanced in the presence of Cu2O nanoparticles

The present study relates to a nanotechnology enabled method in which purified laccase from Escherichia coli AKL2 was supplemented with 100 μM copper oxide nanoparticles (Cu2O) (NP-laccase). The activity, half life and stability of NP-laccase were enhanced by 4, 42 and 36-fold respectively at high temperature (80 °C) and also over a wide range of pH (4–12) than laccase (in the presence of 0.18 mM CuSO4). Thermodynamic analysis of the nanoparticle-induced enzyme stability revealed an enhanced entropy–enthalpy compensation at 80 °C, which reflected the maintenance of its native structure. This was further supported by CD studies. The enhanced activity and thermostability of NP-laccase can be utilized for efficient decolorisation of dyes (both phenolic and azo).

► The activity of laccase is enhanced at high temperature in presence of Cu2O-NP.
► NP-laccase retained its activity for 2 h at 80 °C.
► NP-laccase was found to be pH stable within the range of 4–12.
► NP-laccase had enhanced entropy enthalpy compensation at high temperatures.
► NP-laccase can be potentially used for phenolic and azo dye-decolorization.