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The properties of enzymatic systems based on horseradish root peroxidase immobilized on magnetic particles were studied. Magnetic Fe3O4 nanoparticles were synthesized by co-precipitation. Then, horseradish root peroxidase was immobilized on their surface in two ways by covalent crosslinking. For this purposes, in the first case, Fe3O4 was sequentially treated with tetraethoxysilane, 3-minopropyltriethoxysilane, glutaraldehyde and HRP. In the second case, before immobilization of HRP, 3-minopropyltriethoxysilane, glutaraldehyde and HRP were sequentially deposited onto the support surface. The activity of the synthesized biocatalysts was evaluated spectrophotometrically in the oxidation reaction of 2,2’-azino-bis (3-ethylbenzothiazolin-6-sulfonate) ammonium with hydrogen peroxide. The kinetic parameters K m and V max were also calculated for all types of catalysts, including native HRP. Among all biocatalytic systems, the best values, compared with the native enzyme (K m = 4 mmol/L and V max = 12.6 · 10−4, mmol/L·s), were obtained for the first type of biocatalyst (K m = 5 mmol / L and V max = 2.5 · 10−4, mmol/L·s). It was also determined that the optimum pH is 7.2.

ABSTRACT:In this article we finalize our experimental and theoretical studies on the ( 2 -C 60 )Pd(PPh 3 ) 2 palladium-phosphine fullerene complex. Full scale ab initio quantum-chemical calculations up to the B3LYP/SDDALL level of theory have been performed to determine the structure and electronic spectrum of ( 2 -C 60 )Pd(PPh 3 ) 2 . Based on the results of calculations and experimental data we conclude that the preliminary interaction of the catalyst with the substrate facilitates the interaction of the substrate-catalyst complex with H 2 by decreasing the energy barrier. In conclusions we summarize the results of our studies of the structure and electronic spectrum of the investigated complex, the kinetics of catalytic reactions, the influence of the solvents on the catalyst's activity in the heterogeneous phase, and provide the possible mechanism of catalytic reaction.