Esterification of R/S-ketoprofen with 2-propanol as reactant and solvent catalyzed by Novozym® 435 at selected conditions

MARÍA VICTORIA TOLEDO; CARLA JOSÉ; SEBASTIÁN E. COLLINS ; RITA D. BONETTO; MARÍA LUJÁN FERREIRA; LAURA E. BRIAND

JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 83 p. 108 - 119

1381-1177

The effect of contacting 2-propanol: H2O mixture on Novozym® 435 was investigated at 45 °C for an extended period of time (8 days). Similarly, to previous studies on the effect of ethanol, 2-propanol dissolves the polymethylmethacrylate (PMMA) that constitutes the support of the Candida antarctica B lipase (CALB) although in a lesser extend than ethanol. The alcohol diffuses into the biocatalyst`s beads remaining strongly adsorbed (the alcohol desorption is evidenced only upon heating at 187 °C) and altering the inner texture of the biocatalyst`s beads. Additionally, 2-propanol modifies the secondary structure of the enzyme by decreasing the beta-sheet contribution and increasing the beta-turn structure. The esterification of R/S-ketoprofen with 2-propanol: 4.76% H2O at 45 °C evidenced a lower turnover frequency than the esterification with an ethanol-water mixture. The molecular modelling of the interaction of the substrates with the catalytic triad of the lipase provides evidences that the secondary alcohol exerts an important steric hindrance for the reaction to proceed.