Using Laccases in the Nanoflower to Synthesize Viniferin

Zhuofu Wu, Heng Li, XueJun Zhu, Shuai Li, Zhi Wang, Lei Wang, Zhengqiang Li, Guang Chen
2017 Catalysts  
The laccase-incorporated nanoflower was fabricated and characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM images indicate that the laccase-incorporated nanoflower has a high surface area, which may facilitate the mass transfer of the substrate and the product. FTIR spectrums identify the existence of laccase in the nanoflowers. The novel immobilized laccase was used for the synthesis of viniferin. The reaction conditions had been
more » ... and the laccase-incorporated nanoflower can show its maximum specific activity (16.3 µmol/g/h) under the optimal reaction conditions. The specific activity of the laccase in the nanoflowers is enhanced about 2.2-fold compared with free laccase in solution without copper (II) ions. Furthermore, the laccase in the nanoflowers shows an increase in specific activity of~180% compared with free laccase in a solution containing high concentrations (similar to the concentration in the flower) of copper (II) ions. The results also indicate that the laccase in the nanoflowers retain 93.2% of its initial specific activity even after ten continuous batches. Enzyme immobilization can overcome these limitations [12] [13] [14] [15] . Besides increasing the enzyme reusability and stability, enzyme immobilization can also greatly improve the enzyme activity [16] [17] [18] . The specific activity of the organophosphorus hydrolase can be enhanced about 2.0-fold by entrapping it into the HOOC-functionalized mesoporous silica [19] [20] [21] . M. miehei lipase adsorbed on hydrophobic support is even 20 times more active than its free enzyme [22] . The specific activity of encapsulated β-galactosidase from Aspergillus oryzae increases 1.8-fold compared with the free enzyme [23] . In 2012, a simple and versatile immobilization technology was reported by Zare and his colleagues to gain hybrid organic-inorganic nanoflower composed by various proteins and Cu 3 (PO 4 ) 2 ·3H 2 O [24]. Such hybrid organic-inorganic nanoflowers use copper (II) ions as the inorganic component and various proteins as the organic component. The growth of nanoflower is dominated by the coordination between nitrogen atoms of the amide groups in the protein backbone and copper ions. The laccase-Cu 3 (PO 4 ) 2 ·3H 2 O nanoflowers were also obtained through this method [24] . When the enzyme was used as the protein component of the hybrid nanoflower, the enhanced specific activity and stability could be obtained [25] . In our previous work, we had successfully adopted this method to prepare a novel immobilized lipase for resolution of (R,S)-2-pentanol in organic solvents [26] and found that the lipase in the nanoflowers can exhibit perfect specific activity and excellent reusability. In this study, we prepared the laccase-incorporated nanoflower for efficiently synthesizing viniferin (Scheme 1). The fabricated laccase-incorporated nanoflower was characterized by a scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The reaction conditions for the synthesis of viniferin catalyzed by the immobilized laccase had been optimized and the reusability of the immobilized laccase had also been investigated.
doi:10.3390/catal7060188 fatcat:qhryjsfb7jbcheu6msctvayqyy