Optimization of immobilization conditions of Mucor miehei lipase onto Florisil via polysuccinimide spacer arm using response surface methodology and application of immobilized lipase in asymmetric acylation of 2-amino-1-phenylethanols

Hydroxyapatite/Glycyrrhizin/Lithium-Based Metal-Organic Framework (HA/GL/Li-MOF) Nanocomposite as Support for Immobilization of Thermomyces lanuginosus Lipase

The hydroxyapatite/glycyrrhizin/lithium-based metal-organic framework (HA/GL/Li-MOF) nanocomposites were synthesized via the hydrothermal method in the presence of lecithin and glycyrrhizin. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) were applied for characterization of the fabricated nanocomposites. The HA/GL/Li-MOF and Li-MOF nanocomposites were employed as support for immobilization of Thermomyces lanuginosus lipase (TLL). The Plackett-Burman and Box-Behnken designs were used for screening and optimizing of variables affecting the immobilization conditions, respectively. The optimum specific activity of immobilized TLL on HA/GL/Li-MOF and Li-MOF nanocomposites (41.8 ± 1.2 U/mg and 39.4 ± 3.1 U/mg, respectively) was predictably determined at support concentration of 0.5 mg/mL, glutaraldehyde concentration of 5 mM, and enzyme activity of 20 U/mg, while the specific activities of TLL@ HA/GL/Li-MOF and TLL@Li-MOF were experimentally found to be 39.5 ± 3.7 U/mg and 38.5 ± 2.3 U/mg, respectively. The stability results showed that the TLL@ HA/GL/Li-MOF has suitable stability against pH and thermal denaturation. However, the immobilized TLL on Li-MOF represented lower stability compared with that of the HA/GL/Li-MOF. The immobilized TLL on HA/GL/Li-MOF maintained near 70% of its original activity after 15 days' storage and during 5 runs of application. In addition, TLL@HA/GL/Li-MOF exhibited higher enzyme-substrate affinity (K_m, 10.1 mM) compared to that of TLL@Li-MOF (K_m, 23.4 mM). Therefore, these findings demonstrated the potential use of HA/GL/Li-MOF nanocomposites for enzyme immobilization.

Exploring experimental fitness landscapes for chemical synthesis and property optimization

The topology of experimental fitness landscapes for chemical optimization objectives is assessed through svr-based HDMR modeling.

Efficient kinetic resolution of (±)-menthol by a lipase from Thermomyces lanuginosus

A lipase from Thermomyces lanuginosus (Lipozyme TL IM) exhibited high enantioselectivity for kinetic resolution of (±)-menthol in organic solvent. The various reaction parameters affecting the conversion and enantioselectivity were studied. The optimum reaction conditions for the transesterification reaction were found with vinyl acetate in the solvent of methyl tert-butyl ether with a vinyl acetate:(±)-menthol molar ratio of 5:1 and an enzyme concentration of 200 g/L at 30 °C. In these conditions, (-)-menthyl acetate with 99.3% enantiomeric excess was obtained, whereas the conversion was 34.7% with the reaction time of 12 H at the substrate concentration of 0.5 M. In addition, the enzyme allowed the substrate loading to be increased up to 1.5 M without the decrease of the enantioselectivity. These results indicated that Lipozyme TL IM was a promising biocatalyst in the resolution of (±)-menthol.