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Nanoporous Zeolite-X as a new carrier for laccase immobilization and its application in dyes decolorization

Wehaidy, Hala R., Abdel-Naby, Mohamed A., El-Hennawi, Heba M., Youssef, Hanan F.
Biocatalysis and agricultural biotechnology 2019 v.19 pp. 101135
Gibbs free energy, Polyporus, activation energy, decolorization, dyes, enthalpy, entropy, half life, immobilized enzymes, laccase, nanopores, oxidation, pH, temperature, wastewater
Laccase enzyme from Polyporus durus ATCC 26726 was immobilized on nanoporous Zeolite-X (ZX), with 83% immobilization yield. The immobilization process protected laccase against pH and temperature changes. The activation energy was lowered after immobilization. Compared to the free enzyme the immobilized enzyme displayed higher Km value and lower Vmax. The immobilized laccase exhibited higher half-life values (t1/2), higher decimal reduction time (D-value) and lower deactivation rate constant (Kd) within the temperature range of 50–70 °C. The thermodynamic analysis for substrate oxidation indicated that the enthalpy (ΔH*), entropy (ΔS*), and free energy of transition state (ΔG*E–T) were lower for immobilized laccase. Furthermore, there was an increase in turnover number (kcat) after immobilization. The immobilized laccase could decolorize two dyes and two synthetic wastewater solutions. It retained 100% activity against AB 225 dye after 7 successive decolorization cycles and it could be reused for 11 times with 48% activity loss.