title: Lipase immobilization on smectite nanoclays: characterization and application to the epoxidation of alpha-pinene.
abstract: The immobilization of lipase B from Candida antarctica on smectite group nanoclays (Laponite, SWy-2 and Kunipia), as well as on their organically modified derivatives, was investigated. A combination of techniques, namely X-ray diffraction, thermal analysis, X-ray photoelectron and FT-IR spectroscopy, was used for characterization of the novel immobilized biocatalyst. Structural and biochemical characterization have revealed that the hydrophobic microenvironment created by the organo-modified clays induces minor changes on the secondary structure of the enzyme, resulting in enhanced catalytic behaviour in hydrophobic media. The immobilized lipase on such modified nanoclays can be effectively applied for the indirect epoxidation of alpha-pinene using hydrogen peroxide as substrate. The amount of alpha-pinene epoxide produced in a single-step biocatalytic process is up to 3-fold higher than that of free enzyme or enzyme immobilized in non-modified clays. Moreover, lipase immobilized in modified clays retains up to 90% of its initial activity, even after 48h of incubation in the presence of oxidant, and up to 60% after four reaction cycles, while other forms of the enzyme retain less than 10%.
authors.affiliation: Department of Biological Applications and Technologies, University of Ioannina, GR-45110 Ioannina, Greece.
authors.forename: Aikaterini A
authors.initials: AA
authors.lastname: Tzialla
authors.forename: Ioannis V
authors.initials: IV
authors.lastname: Pavlidis
authors.forename: Marcella P
authors.initials: MP
authors.lastname: Felicissimo
authors.forename: Petra
authors.initials: P
authors.lastname: Rudolf
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Gournis
authors.forename: Haralambos
authors.initials: H
authors.lastname: Stamatis
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D000081008:Bicyclic Monoterpenes; D002175:Candida / Q000201:enzymology; D002384:Catalysis; D000077215:Clay; D004800:Enzymes, Immobilized; D004852:Epoxy Compounds / Q000737:chemistry; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000737:chemistry; D008049:Lipase / Q000737:chemistry*; D039821:Monoterpenes / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014961:X-Ray Diffraction; D014965:X-Rays
chemical_list: D000538:Aluminum Silicates; D000081008:Bicyclic Monoterpenes; D004800:Enzymes, Immobilized; D004852:Epoxy Compounds; D039821:Monoterpenes; D016877:Oxidants; D006861:Hydrogen Peroxide; D008049:Lipase; C005451:alpha-pinene; D000077215:Clay