title: Antioxidants determination with laccase.
abstract: The spectrophotometric method of antioxidants determination using recombinant laccase Polyporus pinsitus (rPpL) and Myceliophthora thermophila (rMtL) was developed. The method includes simultaneous oxidation of the antioxidant and high reactive laccase substrate producing chromophoric radical cation. As laccase substrates ABTS and other high reactive phenoxazine derivatives: 2-phenoxazin-10-yl-ethanol (PET), 3-phenoxazin-10-yl-propane-1-sulfonic acid (PPSA) and 3-phenoxazin-10-yl-propionic acid (PPA) were used. The kinetic data were analysed using a scheme of simultaneous oxidation of the antioxidant and the substrate. In a range of (0.9-7.3)x10(-6)M of Trolox the measurings recovered 91 and 99% of the antioxidant if ABTS and both laccases were used. The recovery varied between 82 and 124% if phenoxazine derivatives were used. The antioxidant activity determined in rich with antioxidants food samples, i.e. date-palm, black raisin, golden raisin, skin of red grape, dice of red grape, fitted the literature data.
authors.affiliation: Institute of Biochemistry, Department of Enzyme Chemistry, Mokslininku 12, LT-08662 Vilnius, Lithuania; Vilnius Gediminas Technical University, Faculty of Fundamental Sciences, Department of Chemistry and Bioengineering, Sauletekio Avenue 11, LT-10223 Vilnius, Lithuania.
authors.forename: Juozas
authors.initials: J
authors.lastname: Kulys
authors.forename: Irina
authors.initials: I
authors.lastname: Bratkovskaja