Protein-Coated Microcrystals from Candida rugosa Lipase: Its Immobilization, Characterization, and Application in Resolution of Racemic Ibuprofen

Abstract

In this study, an economical heterogeneous biocatalyst, protein-coated microcrystals (PCMCs), was prepared from a commercial Candida rugosa lipase (CRL) and used for catalyzing esterification of (R, S)-ibuprofen enantiomers with isooctanol in isooctane. The main variables controlling the process (precipitating solvents, pH, saturated K2SO4 solution, and water content) were optimized via single-factorial experiments. Under optimum conditions, the enantiomeric excess of active S(+)-ibuprofen and total conversion rate were 97.34 and 49.83 %, respectively, and the corresponding enzyme (PCMC-CRL) activity attained 387.29 μmol/min/g protein, a 5.78-fold enhancement over the free lipase powder. Additionally, the thermostability, organic-solvent tolerance, and operational stability of PCMC-CRL were greatly improved as compared to the free enzyme. Fourier transform infrared (FTIR) spectroscopy was employed to reveal the correlation between conformation and enzyme activity enhancement. Moreover, the PCMC-CRL retained most of its original activity following use in more than 15 successive batches, suggesting that it exhibits adequate operational stability. These results indicate that PCMC-CRL is of great potential use in industrial applications.