Lipase B of Candida antarctica Co -adsorbed with Polyols onto TiO 2 Nanoparticles for Improved Biocatalytic Performance

LLERENA-SUSTER, C.R.; TOLEDO, M.V:; FITTIPALDI, A.; MORCELLE DEL VALLE, S.; BRIAND, L.E.

journal of chemical technology and biotechnology

John Wiley & Sons

Año: 2017

BACKGROUND The immobilization of the lipase B of Candida antarctica CALB over TiO2 nanoparticles was thoroughly investigated with the isotherms of adsorption at various temperatures with and without the addition of sorbitol and glycerol. Additionally, the surface composition, secondary structure of the protein and the effect of the addition of the polyols in the catalytic performance of the biocatalysts in the kinetic resolution of R/S-ibuprofen have been addressed in this investigation. RESULTS The maximum dispersion limit of protein on TiO2 NPs is 7.6x10-2mol.m-2 which represents 50% of the theoretical monolayer according to the Langmuir model. The protein and polyols such as glycerol and sorbitol co-adsorb on the surface of the TiO2 NPs. This molecular self-association exerts a positive cooperativism since prevents the aggregation of the protein and protects its active conformation.In fact, the residual esterase activity of the immobilized CALB compared with the free lipase depends directly on the amount of co-adsorbed polyols. The optimized 0.06 CALBGS30/TiO2 catalyzes the esterification of R/S-ibuprofen with ethanol up to 52 % (0.31 mol.min-1.mg-1) and 41 % of enantiomeric excess towards S(+)-ibuprofen in 24 hs of reaction. Under similar reaction conditions, the commercial counterpartNovozym® 435 showed a specific activity of 0.091 ± 0.003 mol.min-1.mg-1 and 16 % of enantiomeric excess.CONCLUSIONS There is a correlation between the temperature of the preparation of the biocatalysts, the amount of adsorbed polyols, the secondary structure of the protein and the catalytic activity. In fact, the higher the temperature of the preparation, the lower is the amount of adsorbed polyols which in turn leads to a higher contribution of aggregates and the lower the catalytic activity.