Enzymatic dimerization of phenylacetylene by laccase immobilized on magnetic nanoparticles via click chemistry

• Published in: Biocatalysis and biotransformation 2019-11, Vol.37 (6), p.455-465
• Main Authors: Mogharabi-Manzari, Mehdi, Heydari, Marjan, Sadeghian-Abadi, Salar, Yousefi-Mokri, Mahsa, Faramarzi, Mohammad Ali
• Format: Article
• Language: English
• Subjects: click chemistry; enzyme immobilization; heterogeneous catalyst; Laccase; phenylacetylene
• ISSN: 1024-2422; 1029-2446
• DOI: 10.1080/10242422.2019.1611788

A heterogeneous biocatalyst composed of laccase immobilized on Fe 3 O 4 magnetic nanoparticles was prepared via a click chemistry reaction for dimerization of phenylacetylene. The physical and chemical characteristics of the catalyst were investigated. Yield and efficiency of immobilization were 68.7% and 76.4%, respectively. The apparent K m value of the immobilized laccase on nanoparticles was 1.5-fold greater than the value of the free enzyme, and the calculated V max of free and immobilized laccase was 65 mM min ‒1 and 43 mM min ‒1 , respectively. While the free enzyme completely lost its activity, more than 60% of the initial activity of immobilized laccase was conserved after 30 days. Oxidative dimerization of phenylacetylene was performed using the prepared catalyst and 2,2,6,6-tetramethylpiperidine1-oxyl (TEMPO) as a mediator. The maximum yield was obtained at optimal conditions: immobilized laccase (100 mg, ∼80 U), TEMPO (4 mol%), 40 °C, pH 4.5, and 6 h incubation time. Additional environmental and eco-friendly aspects of this heterogeneous biocatalyst are its potential catalytic activity and ease of separation of the catalyst from the reaction mixture by an external magnetic field. Highlights A heterogeneous biocatalyst was prepared by immobilization of laccase on Fe 3 O 4 nanoparticles. 6-Hepynoic acid was used as a linker via a click reaction. The heterogeneous biocatalyst was used in dimerization of phenylacetylene. A maximal yield was obtained after a 6 h-incubation at 40 °C and a pH of 4.5. The catalyst was reused up to 15 runs with more than 80% conversion.