A highly efficient immobilized MAS1 lipase for the glycerolysis reaction of n-3 PUFA-rich ethyl esters

Efficient Enzymatic Enrichment of High-purity Nervonic Acid from Malania oleifera Seed Oil

Nervonic acid (NA) is a monounsaturated fatty acid vital for brain health and is of emerging importance in various industrial applications, including therapeutics, food, and cosmetics. Given the growing demands of the food and pharmaceutical industries, there's a pressing need for high-purity NA. Previously, NA constituents in plant seed oils were chemically transformed into nervonic acid ethyl ester (NAEE) to facilitate extraction from seed oils. In this study, we present an enzymatic approach to convert NA constituents in Malania oleifera seed oil to NAEE. Combined with the utilization of the semi-preparative chromatography, we achieved a remarkable purity of 97.52% NAEE. Compared to conventional chemical preparations characterized by multiple steps, prolonged processing times, and low yields and purities, our enzymatic method stands out as a more efficient and advantageous alternative. On top of that, this innovative approach is environmentally friendly and circumvents health and safety issues associated with chemical processes.

Structural Basis for the Regiospecificity of a Lipase from Streptomyces sp. W007

The efficiency and accuracy of the synthesis of structural lipids are closely related to the regiospecificity of lipases. Understanding the structural mechanism of their regiospecificity contributes to the regiospecific redesign of lipases for meeting the technological innovation needs. Here, we used a thermostable lipase from Streptomyces sp. W007 (MAS1), which has been recently reported to show great potential in industry, to gain an insight into the structural basis of its regiospecificity by molecular modelling and mutagenesis experiments. The results indicated that increasing the steric hindrance of the site for binding a non-reactive carbonyl group of TAGs could transform the non-specific MAS1 to a α-specific lipase, such as the mutants G40E, G40F, G40Q, G40R, G40W, G40Y, N45Y, H108W and T237Y (PSI > 80). In addition, altering the local polarity of the site as well as the conformational stability of its composing residues could also impact the regiospecificity. Our present study could not only aid the rational design of the regiospecificity of lipases, but open avenues of exploration for further industrial applications of lipases.

Immobilized MAS1 Lipase-catalyzed Synthesis of n-3 PUFA-rich Triacylglycerols in Deep Eutectic Solvents

n-3 polyunsaturated fatty acids (PUFA)-rich triacylglycerols (TAG) with many beneficial effects are still difficult to be synthesized efficiently and rapidly by current synthetic techniques. This study reports the fatty acid specificity of immobilized MAS1 lipase and its efficient synthesis of n-3 PUFA-rich TAG by esterification of glycerol with n-3 PUFA in natural deep eutectic solvents (NADES) systems. Immobilized MAS1 lipase showed the highest preference for capric acid [C10:0, the highest specificity constant (1/α)=1] whereas it discriminated strongly against docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) due to their lowest specificity constants (1/α=0.19 and 0.2). Moreover, the highest n-3 PUFA-rich TAG content (55.8%) with similar n-3 PUFA composition to the substrate was obtained in choline chloride/glycerol (CG) system. There was a 1.38-fold increase of TAG content in CG system compared with that in the solvent-free system. Interestingly, immobilized MAS1 lipase exhibited no regiospecificity in the solvent-free and various NADES systems. Besides, the potential reaction mechanism of immobilized MAS1 lipase-catalyzed esterification of glycerol with n-3 PUFA in NADES systems was described. It was found that the use of NADES as solvents could greatly enhance TAG content, and make it easy to separate the product. These results indicated that immobilized MAS1 lipase is a promising biocatalyst for the efficient synthesis of n-3 PUFA-rich TAG by esterification of glycerol with n-3 PUFA in NADES systems.

An Efficient Synthesis of Lysophosphatidylcholine Enriched with n-3 Polyunsaturated Fatty Acids by Immobilized MAS1 Lipase

n-3 polyunsaturated fatty acid (PUFA)-rich lysophosphatidylcholine (LPC) with many beneficial effects was effectively synthesized by immobilized MAS1 lipase-catalyzed esterification of n-3 PUFA with sn-glycero-3-phosphatidylcholine (GPC) under vacuum in a solvent-free system. Immobilized MAS1 lipase was found to be a more suitable catalyst for the production of n-3 PUFA-rich LPC when compared with Novozym 435. The maximal GPC conversion and LPC content (93.12% and 90.77 mol %) were obtained under the optimized conditions (enzyme loading of 300 U/g substrate, temperature of 55 °C, and n-3 PUFA/GPC molar ratio of 20:1). Moreover, it was observed that 1-acyl-sn-glycero-3-lysophosphatidylcholine (sn-1 acyl LPC) was the main reaction product, as demonstrated by molecular docking. These results showed that immobilized MAS1 lipase had high phospholipase activity with a predominant specificity for the sn-1 hydroxyl position of GPC to efficiently synthesize highly pure n-3 PUFA-rich LPC from GPC for industrial application.

Insight into the Modification of Phosphatidylcholine with n-3 Polyunsaturated Fatty Acids-Rich Ethyl Esters by Immobilized MAS1 Lipase

This study reported the modification of phosphatidylcholine (PC) with n-3 polyunsaturated fatty acids (PUFA)-rich ethyl esters (EE) by immobilized MAS1 lipase-catalyzed transesterification in the solvent-free system. Effects of n-3 PUFA-rich EE/PC mass ratio, enzyme loading, reaction temperature, and water dosage on the incorporation of n-3 PUFA into PC were investigated, respectively. The results indicate that the maximum incorporation of n-3 PUFA into PC reached 33.5% (24 h) under the following conditions: n-3 PUFA-rich EE/PC mass ratio of 6:1, enzyme loading of 20%, reaction temperature of 55 °C, and water dosage of 1.0%. After 72 h of reaction, the incorporation of n-3 PUFA into PC was 43.55% and the composition of the reaction mixture was analyzed by ³¹P nuclear magnetic resonance (NMR). The results show that the reaction product consisted of 32.68% PC, 28.76% 1-diacyl-sn-glycero-3-lysophosphatidylcholine (sn-1 LPC), 4.90% 2-diacyl-sn-glycero-3-lysophosphatidylcholine (sn-2 LPC), and 33.60% sn-glycero-3-phosphatidylcholine (GPC). This study offers insight into the phospholipase activity of immobilized MAS1 lipase and suggests the extended applications of immobilized MAS1 lipase in the modification of phospholipids for industrial purpose.

A Thermostable Monoacylglycerol Lipase from Marine Geobacillus sp. 12AMOR1: Biochemical Characterization and Mutagenesis Study

Lipases with unique substrate specificity are highly desired in biotechnological applications. In this study, a putative marine Geobacillus sp. monoacylglycerol lipase (GMGL) encoded gene was identified by a genomic mining strategy. The gene was expressed in Escherichia coli as a His-tag fusion protein and purified by affinity chromatography with a yield of 264 mg per liter fermentation broth. The recombinant GMGL shows the highest hydrolysis activity at 60 °C and pH 8.0, and the half-life was 60 min at 70 °C. The GMGL is active on monoacylglycerol (MAG) substrate but not diacylglycerol (DAG) or triacylglycerol (TAG), and produces MAG as the single product in the esterification reaction. Modeling structure analysis showed that the catalytic triad is formed by Ser97, Asp196 and His226, and the flexible cap region is constituted by residues from Ala120 to Thr160. A mutagenesis study on Leu142, Ile145 and Ile170 located in the substrate binding tunnel revealed that these residues were related with its substrate specificity. The k_cat/K_m value toward the pNP-C6 substrate in mutants Leu142Ala, Ile145Ala and Ile170Phe increased to 2.3-, 1.4- and 2.2-fold as compared to that of the wild type, respectively.

Two-Stage Enzymatic Preparation of Eicosapentaenoic Acid (EPA) And Docosahexaenoic Acid (DHA) Enriched Fish Oil Triacylglycerols

Fish oil products in the form of triacylglycerols generally have relatively low contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and so it is of potential research and industrial interest to enrich the related contents in commercial products. Thereby an economical and efficient two-stage preparation of EPA and DHA enriched fish oil triacylglycerols is proposed in this study. The first stage was the partial hydrolysis of fish oil by only 0.2 wt.‰ AY "Amano" 400SD which led to increases of EPA and DHA contents in acylglycerols from 19.30 and 13.09 wt % to 25.95 and 22.06 wt %, respectively. Subsequently, products of the first stage were subjected to transesterification with EPA and DHA enriched fatty acid ethyl esters (EDEE) as the second stage to afford EPA and DHA enriched fish oil triacylglycerols by using as low as 2 wt % Novozyme 435. EDEEs prepared from fish oil ethyl ester, and recycled DHA and EPA, respectively, were applied in this stage. Final products prepared with two different sources of EDEEs were composed of 97.62 and 95.92 wt % of triacylglycerols, respectively, with EPA and DHA contents of 28.20 and 21.41 wt % for the former and 25.61 and 17.40 wt % for the latter. Results not only demonstrate this two-stage process's capability and industrial value for enriching EPA and DHA in fish oil products, but also offer new opportunities for the development of fortified fish oil products.