Molecular rules for selectivity in lipase-catalysed acylation of lysine

Biocatalytic Regioselective O-acylation of Sesquiterpene Lactones from Chicory: A Pathway to Novel Ester Derivatives

We report the first biocatalytic modification of sesquiterpene lactones (STLs) found in the chicory plants, specifically lactucin (Lc), 11β,13-dihydrolactucin (DHLc), lactucopicrin (Lp), and 11β,13-dihydrolactucopicrin (DHLp). The selective O-acylation of their primary alcohol group was carried out by the lipase B from Candida antarctica (CAL-B) using various aliphatic vinyl esters as acyl donors. Perillyl alcohol, a simpler monoterpenoid, served as a model to set up the desired O-acetylation reaction by comparing the use of acetic acid and vinyl acetate as acyl donors. Similar conditions were then applied to DHLc, where five novel ester chains were selectively introduced onto the primary alcohol group, with conversions going from >99 % (acetate and propionate) to 69 % (octanoate). The synthesis of the corresponding O-acetyl esters of Lc, Lp, and DHLp was also successfully achieved with near-quantitative conversion. Molecular docking simulations were then performed to elucidate the preferred enzyme-substrate binding modes in the acylation reactions with STLs, as well as to understand their interactions with crucial amino acid residues at the active site. Our methodology enables the selective O-acylation of the primary alcohol group in four different STLs, offering possibilities for synthesizing novel derivatives with significant potential applications in pharmaceuticals or as biocontrol agents.

Lipopeptides as tools in catalysis, supramolecular, materials and medicinal chemistry

Lipopeptides are amphiphilic peptides in which an aliphatic chain is attached to either the C or N terminus of peptides. Their self-assembly - into micelles, vesicles, nanotubes, fibres or nanobelts - leads to applications in nanotechnology, catalysis or medicinal chemistry. Self-organization of lipopeptides is dependent on both the length of the lipid tail and the amino acid sequence, in which the chirality of the peptide sequence can be transmitted into the supramolecular species. This Review describes the use of lipopeptides to design synthetic advanced dynamic supramolecular systems, nanostructured materials or self-responsive delivery systems in the area of medical biotechnology. We examine the influence of external stimuli, the ability of lipopeptide-derived structures to adapt over time and their application as medicinal agents with antibacterial, antifungal, antiviral or anticancer activities. Finally, we discuss the catalytic efficiency of lipopeptides, with the aim of building minimal synthetic enzymes, and recent efforts to incorporate metals into lipopeptide assemblies.

Yeast Lipid Produced through Glycerol Conversions and Its Use for Enzymatic Synthesis of Amino Acid-Based Biosurfactants

The aim of the present work was to obtain microbial lipids (single-cell oils and SCOs) from oleaginous yeast cultivated on biodiesel-derived glycerol and subsequently proceed to the enzymatic synthesis of high-value biosurfactant-type molecules in an aqueous medium, with SCOs implicated as acyl donors (ADs). Indeed, the initial screening of five non-conventional oleaginous yeasts revealed that the most important lipid producer was the microorganism Cryptococcus curvatus ATCC 20509. SCO production was optimised according to the nature of the nitrogen source and the initial concentration of glycerol (Glyc0) employed in the medium. Lipids up to 50% w/w in dry cell weight (DCW) (SCO_max = 6.1 g/L) occurred at Glyc0 ≈ 70 g/L (C/N ≈ 80 moles/moles). Thereafter, lipids were recovered and were subsequently used as ADs in the N-acylation reaction catalysed by aminoacylases produced from Streptomyces ambofaciens ATCC 23877 under aqueous conditions, while Candida antarctica lipase B (CALB) was used as a reference enzyme. Aminoacylases revealed excellent activity towards the synthesis of acyl-lysine only when free fatty acids (FAs) were used as the AD, and the rare regioselectivity in the α-amino group, which has a great impact on the preservation of the functional side chains of any amino acids or peptides. Aminoacylases presented higher α-oleoyl-lysine productivity and final titer (8.3 g/L) with hydrolysed SCO than with hydrolysed vegetable oil. The substrate specificity of both enzymes towards the three main FAs found in SCO was studied, and a new parameter was defined, viz., Specificity factor (Sf), which expresses the relative substrate specificity of an enzyme towards a FA present in a FA mixture. The Sf value of aminoacylases was the highest with palmitic acid in all cases tested, ranging from 2.0 to 3.0, while that of CALB was with linoleic acid (0.9-1.5). To the best of our knowledge, this is the first time that a microbial oil has been successfully used as AD for biosurfactant synthesis. This bio-refinery approach illustrates the concept of a state-of-the-art combination of enzyme and microbial technology to produce high-value biosurfactants through environmentally friendly and economically sound processes.

Microbial Lipases and Their Potential in the Production of Pharmaceutical Building Blocks

Processes involving lipases in obtaining active pharmaceutical ingredients (APIs) are crucial to increase the sustainability of the industry. Despite their lower production cost, microbial lipases are striking for their versatile catalyzing reactions beyond their physiological role. In the context of taking advantage of microbial lipases in reactions for the synthesis of API building blocks, this review focuses on: (i) the structural origins of the catalytic properties of microbial lipases, including the results of techniques such as single particle monitoring (SPT) and the description of its selectivity beyond the Kazlauskas rule as the “Mirror-Image Packing” or the “Key Region(s) rule influencing enantioselectivity” (KRIE); (ii) immobilization methods given the conferred operative advantages in industrial applications and their modulating capacity of lipase properties; and (iii) a comprehensive description of microbial lipases use as a conventional or promiscuous catalyst in key reactions in the organic synthesis (Knoevenagel condensation, Morita–Baylis–Hillman (MBH) reactions, Markovnikov additions, Baeyer–Villiger oxidation, racemization, among others). Finally, this review will also focus on a research perspective necessary to increase microbial lipases application development towards a greener industry.

Industrial biotransformations catalyzed by microbial lipases: screening platform and commercial aspects

The successfulness of a lipase-catalyzed industrial process depends on a proper lipase selection. In this work, an alternative screening platform for industrially important biotransformations catalyzed by microbial lipases was proposed. Thus, the reactivity of sixty lipase activities from spore-forming microorganisms towards hydrolytic and transesterification reactions by using p-nitrophenyl palmitate as a chromogenic acyl donor substrate was explored. Only three biocatalysts were capable of catalyzing all reactions tested. Fourteen biocatalysts did not show hydrolytic activity at all; however, they displayed transesterification activities using ethanol, starch, low-methoxyl (LM) pectin, high-methoxyl (HM) pectin, or vitamin C as acyl acceptors. Using heat-treated biocatalysts, hydrolytic activities were not highly correlated with the corresponding transesterification activities using ethanol (r =  -0.058, p = 0.660), starch (r = 0.431, p = 0.001), LM pectin (r =  -0.010, p = 0.938), HM pectin (r = 0.167, p = 0.202), and vitamin C (r =  -0.048, p = 0.716) as acyl acceptor. In addition, to the best of our knowledge, several transesterification activities produced from microorganisms of the genus Bacillus, Brevibacillus, Lysinibacillus, Geobacillus, or Sporosarcina were reported for first time. Finally, the global lipase market was presented and segmented by date, application, geography and player highlighting the commercial contribution of microbial lipases.

Effect of the acyl-group length on the chemoselectivity of the lipase-catalyzed acylation of propranolol-a computational study

The selective N-acylation of 1,2-amino alcohols has been proposed to occur through the proton shuttle mechanism. However, the O-acetylation of propranolol catalyzed by Candida antarctica lipase B is an exception. We investigated the relation between the chemoselectivity of this reaction and the acyl group length. For this purpose, we compared the acyl groups: ethanoyl, butanoyl, octanoyl, and hexadecanoyl. We studied the Michaelis complexes between serine-acylated Candida antarctica lipase B and propranolol, employing a computational approach that involved sampling Michaelis complex conformations through ensemble docking plus consensus scoring and molecular dynamics simulations. The conformations were then classified as near attack conformations for acylation of the amino or hydroxy group. The relative populations of these two classes of conformations were found to be consistent with the experimentally observed chemoselective O-acetylation. We predict that increasing the length of the hydrocarbon chain of the acyl group will cause O-acylation to be unfavorable with respect to N-acylation. The nucleophilic attack of propranolol to the acylated lipase was found to be more favorable through the classical mechanism when compared with the proton shuttle mechanism.

One-Step Synthesis of 4-Octyl Itaconate through the Structure Control of Lipase

4-Octyl itaconate is a novel antiviral and immunoregulatory small molecule showing great potential in the treatment of various autoimmune diseases and viral infections. It is difficult to selectively esterify the C4 carboxyl group of itaconate acid via one-step direct esterification using chemical catalysts, while the two-step route with itaconic anhydride as an intermediate is environmentally unfriendly and costly. This research investigated the one-step and green synthesis of 4-octyl itaconate through the structure control of lipase, obtaining 4-octyl itaconate with over 98% yield and over 99% selectivity. Multiscale molecular dynamics simulations were applied to investigate the reaction mechanism. The cavity pocket of lipases resulted in a 4-octyl itaconate selectivity by affecting distribution of substrates toward the catalytic site. Toluene could enhance monoesterification in the C4 carboxyl group and contribute to a nearly 100% conversion from itaconate acid into 4-octyl itaconate by adjusting the catalytic microenvironment around the lipase, producing a shrinkage effect on the channel.

Single Cell Oil (SCO)-Based Bioactive Compounds: I-Enzymatic Synthesis of Fatty Acid Amides Using SCOs as Acyl Group Donors and Their Biological Activities

Fatty acid amides (FAAs) are of great interest due to their broad industrial applications. They can be synthesized enzymatically with many advantages over chemical synthesis. In this study, the fatty acid moieties of lipids of Cunninghamella echinulata ATHUM 4411, Umbelopsis isabellina ATHUM 2935, Nannochloropsis gaditana CCAP 849/5, olive oil, and an eicosapentaenoic acid (EPA) concentrate were converted into their fatty acid methyl esters and used in the FAA (i.e., ethylene diamine amides) enzymatic synthesis, using lipases as biocatalysts. The FAA synthesis, monitored using in situ NMR, FT-IR, and thin-layer chromatography, was catalyzed efficiently by the immobilized Candida rugosa lipase. The synthesized FAAs exhibited a significant antimicrobial activity, especially those containing oleic acid in high proportions (i.e., derived from olive oil and U. isabellina oil), against several human pathogenic microorganisms, insecticidal activity against yellow fever mosquito, especially those of C. echinulata containing gamma-linolenic acid, and anticancer properties against SKOV-3 ovarian cancer cell line, especially those containing EPA in their structures (i.e., EPA concentrate and N. gaditana oil). We conclude that FAAs can be efficiently synthesized using microbial oils of different fatty acid composition and used in specific biological applications.

Significantly Enhanced Synthesis of Aromatic Esters of Arbutin Catalyzed by Immobilized Lipase in Co-solvent Systems

Highly efficient and regioselective synthesis of pharmacologically interesting aromatic esters of arbutin catalyzed by immobilized lipase from Penicillium expansum in co-solvent systems was successfully carried out. As compared to tetrahydrofuran solvent, the initial rate and substrate conversion of arbutin vanilylation were markedly enhanced in tetrahydrofuran-isopropyl ether (20%, v/v). Moreover, the effects of three reaction parameters (enzyme amount, temperature and substrate molar ratio of vinyl vanillic acid to arbutin) on 6′-O-vanilloyl-arbutin synthesis were scrutinized and the key process parameters were optimized using response surface methodology (RSM). The experimental data were fitted well to a second order polynomial model by using multiple regression analysis. The best combination of variables was 50°C, 93 U/mL and 11 for the reaction temperature, the enzyme amount and mole ratio of arbutin to vinyl vanilic acid, respectively, and which the reaction rate, substrate conversion and regioselectivity were as high as 8.2 mM/h, 93 and 99%. It was worth noting that a variety of aromatic esters of arbutin were obtained with much higher conversion (93–99%) at these optimal conditions.

N-acylation of L-amino acids in aqueous media: Evaluation of the catalytic performances of Streptomyces ambofaciens aminoacylases

N-acylated amino acids are widely used as surfactants and/or actives in cosmetics and household formulations. Their industrial production is based on the use of the Schotten-Baumann chemical and unselective reaction. Faced to the growing demand for greener production processes, selective enzymatic synthesis in more environment-friendly conditions starts to be considered as a potential alternative. This study concerns the use of the aminoacylases from Streptomyces ambofaciens to selectively catalyse aminoacid acylation reaction by fatty acids in aqueous medium. The results demonstrated that, when using undecylenoic acid as acyl donor, these aminoacylases properly catalyse the acylation of 14 of the 20 proteogenic l-amino acids tested on their α amino group with a great variability depending on the nature of the amino acid (polar or not, positively/negatively charged, aromatic or not…). More precisely, the following 9 amino acids were shown to be preferentially acylated by S. ambofaciens aminoacylases as follows: lysine > arginine > leucine > methionine > phenylalanine > valine > cysteine > isoleucine > threonine. Different fatty acids were used as acyl donors and, in most cases, the fatty acid length influenced the conversion yield. The kinetic study of α-lauroy-lysine synthesis showed a positive influence of lysine concentration with Vmax and Km of 3.7 mM/h and 76 mM, respectively. Besides, the lauric acid had an inhibitory effect on the reaction with Ki of 70 mM. The addition of cobalt to the reaction medium led to a more than six-fold increase of the reaction rate. These results, achieved with the aminoacylases from S. ambofaciens represent an improved enzyme-based N-acylated amino acids production in order to provide an alternative way to the Schotten-Baumann chemical reaction currently used in the industry.