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Abstract
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Oxidation of alcohols to their corresponding carbonyl products is one of the fundamental transformations in organic chemistry. Laccases (p-benzenediol: oxygen oxidoreductase)are extracellular enzymes that belong to the multicopper polyphenol oxidases, which catalyze the four single electron oxidation of electron-rich compounds, usually phenols or aromatic amines. The redox potential of laccase alone is not high enough to break carbon-hydrogen aliphatic bonds such as alcohols compound. This limitation has been overcome by using redox mediators such as 2,2',6,6'-tetramethylpiperidine-N-oxyl(TEMPO), HBT and et all in the so-called laccase-mediator systems (LMS). However, despite laccase having intrinsic appreciable stability, the enzyme is often easily inactivated in practical application due to a wide variety of environmental conditions. In addition, it is also difficult to be separated from the reaction system for reuse. It is well-known that the immobilization of enzymes on insoluble supports provides an effective way to perform enzyme reuse and to improve its stability. In this research, laccase from Trametes Versicolor was successfully immobilized through chemical bonding on an modified MNPs support and characterized using a variety of different techniques.Thermal and pH stabilities of magnetic nanoparticles immobilized Laccase (MNPs-Laccase) are improved and the their separation from the reaction mixture is rapid, simple, economical. Laccase@MNPs catalyzed selective aerobicoxidation of benzylic alcohols to corresponding aromatic aldehydes in the presence of TEMPO as a mediator with good to high yields in aqueous media at room temperature Summry, the characteristic aspects of MNPs-Laccase as a nanobiocatalyst are thermal and pH stabilities and rapid, simple and efficient separation by using an appropriate external magnet, which minimizes the loss of catalyst during separation and reusability for several times without any significant loss of activity. The method
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