Amino acid induced hyper activation of laccase and its application in dye degradation.

Abstract The catalytic efficiency of enzyme is mainly dependent on its structural conformation and its stability. In this work, laccase, the copper containing enzyme was stabilized with the help of 20 different natural amino acids by non-covalent interactions. It was seen that the positively charged amino acids viz arginine, histidine and lysine induced the favourable conformation changes in laccase which led to the enhancement in catalytic activity. Further, the thermal stability of laccase-amino acid conjugates was tested in terms of the deactivation energy (E d) and half-life (t 1/2) which showed superior thermal stability in the temperature range of 45–65 °C with respect to free form. In Michaelis-Menten kinetics studies, positively charged amino acid conjugates exhibited higher V max than free laccase. To understand the mechanism of binding of amino acids to laccase and thereby induced conformational changes in laccase, FT-IR data analysis tools and intrinsic fluorescence spectroscopy method were used. At the end, laccase-amino acid conjugates have been employed for enzymatic decolourization of dye solutions and the decolourization was found to be enhanced as compared to that by unconjugated form. Highlights • Positively charged amino acid induced hyper activation of laccase by non-covalent interaction. • In kinetics studies, positively charged amino acid conjugate exhibited higher V max than free form. • FT-IR data analysis revealed the structural conformational changes induced by amino acids. • Laccase-amino acid conjugates have been employed for enzymatic decolourization of dye solutions. [ABSTRACT FROM AUTHOR]