Investigation of steapsin lipase for kinetic resolution of secondary alcohols and synthesis of valuable acetates in non-aqueous reaction medium

Computational and experimental identification of an exceptionally efficient ethyl ester synthetase with broad substrate specificity and high product yield, suggests potential for industrial biocatalysis

Transesterification plays a crucial role in the synthesis of diverse esters in organic synthesis but is barely reported in biocatalysis. Here, we computationally identify the salicylic acid-binding protease 2 (SABP2) as an efficient ethyl ester bond synthetase by QM/MM MD and free energy simulations and present the practical and effective utilization of SABP2 as an eco-friendly biocatalyst for transesterification reactions by a series of experiments. Our findings demonstrate that SABP2 efficiently catalyzes the transesterification reaction between the carboxyl acid group of promiscuous aromatic substrates and ethanol to produce the corresponding ethyl esters. Notably, while SABP2 exhibits its native capability to catalyze the hydrolysis of the methyl salicylate (MeSA), the transesterification rate (producing ethyl salicylate, EtSA) is about 3500 times higher than the hydrolysis rate. Additionally, a range of aromatic methyl esters are employed in the transesterification process, resulting in high yields (up to 98.9 %) of the corresponding ethyl esters. These results indicate a broad substrate scope for SABP2-catalyzed transesterification reactions, demonstrating its potential as a valuable biocatalyst for ester synthesis in industry.

Immobilization of Candida antarctica Lipase on Nanomaterials and Investigation of the Enzyme Activity and Enantioselectivity

This study defines the lipase immobilization protocol and enzymatic kinetic resolution of 1-phenyl ethanol with the use of immobilized lipases (LI) as a biocatalyst. Commercially available lipase Candida antarctica B (Cal-B) was immobilized onto graphene oxide (GO), iron oxide (Fe₃O₄) nanoparticles, and graphene oxide/iron oxide (GO/Fe₃O₄) nanocomposites. Characterization of pure and enzyme-loaded supports was carried out by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The influences of pH, temperature, immobilization time, crosslinker concentration, glutaraldehyde (GLA), epichlorohydrin (EPH), and surfactant concentrations (Tween 80 and Triton X-100) on the catalytic activity were evaluated for these three immobilized biocatalysts. The highest immobilized enzyme activities were 15.03 U/mg, 14.72 U/mg, and 13.56 U/mg for GO-GLA-CalB, Fe₃O₄-GLA-CalB, and GO/Fe₃O₄-GLA-CalB, respectively. Moreover, enantioselectivity and reusability of these immobilized lipases were compared for the kinetic resolution of 1-phenyl ethanol, using toluene as organic solvent and vinyl acetate as acyl donor. The highest values of enantiomeric excess (ee_s = 99%), enantioselectivity (E = 507.74), and conversion (c = 50.73%) were obtained by using lipase immobilized onto graphene oxide (GO-GLA-CalB). It was obtained that this enzymatic process may be repeated five times without important loss of enantioselectivity.

Biocatalysis of aromatic benzyl-propionate ester by different immobilized lipases

Benzyl propionate is an aromatic ester that possesses a fruity odor and is usually found in nature in the composition of some fruits such as plums and melons. This work aimed for the benzyl propionate synthesis by esterification using a new immobilized enzyme preparation with low-cost material from Candida antarctica (NS 88011) and three commercial immobilized lipases (Novozym 435, Lipozyme TL-IM and Lipozyme RM-IM). Novozym 435 had the best performance even when the solvent tert-butanol was absent of the reaction medium. Results from a 2² factorial design showed that an increase in the enzyme amount led to a higher conversion, even when the temperature was kept at the low value. Currently, no research had synthesized successfully benzyl propionate via esterification mediated by lipases; and we reached an ester conversion of ~ 44% after 24 h indicating that it is a promising route for benzyl propionate biotechnological production.

Highly efficient synthesis of arbutin esters catalyzed by whole cells ofCandida parapsilosis

Acylation modification of phenol glycosides is currently of great interest due to the improved bioavailability and multiple functions.

Efficient kinetic resolution of secondary alcohols using an organic solvent-tolerant esterase in non-aqueous medium

OBJECTIVE

To identify an esterase-mediated kinetic resolution of secondary alcohols in non-aqueous medium.

RESULTS

An esterase, EST4, from a marine mud metagenomic library, showed high activity and enantioselectivity for the kinetic resolution of secondary alcohols in non-aqueous medium. Using 1-phenylethanol as the model alcohol, the effects of organic solvents, acyl donors, molar ratio, temperatures and biocatalyst loading on the kinetic resolution catalyzed by the EST4 whole-cell biocatalyst were investigated and optimized. The optimized methodology was effective on resolving 16 various racemic secondary alcohols in neat n-hexane, providing excellent enantiomeric excess (up to 99.9 % ee). Moreover, EST4 exhibited a strong tolerance for high substrate concentration (up to 1 M), and the optical purity of the desired secondary alcohols was kept above 99 % ee.

CONCLUSION

The esterase EST4 is a promising biocatalyst for the enantioselective synthesis of various alcohols and esters with interesting practical applications.

Kinetic resolution of secondary alcohols with Burkholderia cepacia lipase immobilized on a biodegradable ternary blend polymer matrix as a highly efficient and heterogeneous recyclable biocatalyst

A greener and superficial protocol for the synthesis of enantiomerically pure alcohols and their enantioriched acetate derivatives using a biodegradable heterogeneous recyclable catalyst with high conversion has been developed.

Lipase-catalyzed kinetic resolution of (±)-1-(2-furyl) ethanol in nonaqueous media

S-1-(2-Furyl) ethanol serves as an important chiral building block for the preparation of various natural products, fine chemicals, and is widely used in the chemical and pharmaceutical industries. In this work, lipase-catalyzed kinetic resolution of (R/S)-1-(2-furyl) ethanol using different acyl donors was investigated. Vinyl esters are good acyl donors vis-à-vis alkyl esters for kinetic resolution. Among them, vinyl acetate was found to be the best acyl donor. Different immobilized lipases such as Rhizomucor miehei lipase, Thermomyces lanuginosus lipase, and Candida antarctica lipase B were evaluated for this reaction, among which C. antarctica lipase B, immobilized on acrylic resin (Novozym 435), was found to be the best catalyst in n-heptane as solvent. The effect of various parameters was studied in a systematic manner. Maximum conversion of 47% and enantiomeric excess of the substrate (ees ) of 89% were obtained in 2 h using 5 mg of enzyme loading with an equimolar ratio of alcohol to vinyl acetate at 60 °C at a speed of 300 rpm in a batch reactor. From the analysis of progress curve and initial rate data, it was concluded that the reaction followed the ordered bi-bi mechanism with dead-end ester inhibition. Kinetic parameters were obtained by using nonlinear regression. This process is more economical, green, and easily scalable than the chemical processes.