Improved Stability of Aspergillus oryzae α-Amylase Immobilized on Polyaniline Tin Oxide Nanocomposites

Abstract: In the present study, an immobilization support, Polyaniline tin oxide nanocomposite (PANI-SnO2- NC) was synthesized by in situ polymerization of aniline and ammonium peroxydisulphate. The prepared nanocomposite was characterized by various state-of-the-art techniques. The average size of native SnO2-NPs and PANI-SnO2-NC was 65±19 nm and 93±15 nm, respectively. An important industrial enzyme, α-amylase from Aspergillus oryzae was immobilized on PANI-SnO2-NC, which retained 87% enzyme activity. The improved stability of the immobilized enzyme was noticed against pH and temperature, as it retained 65% activity at 60 °C while the free enzyme exhibited 41% activity under similar experimental conditions. Moreover, PANI-SnO2- NC-immobilized α-amylase produced starch (26.42 mg mL–1) more efficiently than free enzyme (20.90 mg mL– 1) after 8 h in batch hydrolysis. PANI-SnO2-NC-bound α-amylase exhibited 54% activity after eight repeated uses. Molecular docking analysis of α-amylase with PANI suggested the ligand binding site to be located quite far away from the active site of the enzyme.