A Whole-Process Visible Strategy for the Preparation of Rhizomucor miehei Lipase with Escherichia coli Secretion Expression System and the Immobilization.

BACKGROUND: Rhizomucor miehei (RM) lipase is a regioselective lipase widely used in food, pharmaceutical and biofuel industries. However, the high cost and low purity of the commercial RM lipase limit its industrial applications. Therefore, it is necessary to develop cost-effective strategies for large-scale preparation of this lipase. The present study explored the high-level expression of RM lipase using superfolder green fluorescent protein (sfGFP)-mediated Escherichia coli secretion system. RESULTS: The sfGFP(-15) mutant was fused to the C-terminus of RM lipase to mediate its secretion expression. The yield of the fusion protein reached approximately 5.1 g/L with high-density fermentation in 5-L fermentors. Unlike conventional secretion expression methods, only a small portion of the target protein was secreted into the cell culture while majority of the fusion protein was still remained in the cytoplasm. However, in contrast to intracellular expression, the target protein in the cytoplasm could be transported efficiently to the supernatant through a simple washing step with equal volume of phosphate saline (PBS), without causing cell disruption. Hence, the approach facilitated the downstream purification step of the recombinant RM lipase. Moreover, contamination or decline of the engineered strain and degradation or deactivation of the target enzyme can be detected efficiently because they exhibited bright green fluorescence. Next, the target protein was immobilized with anion-exchange and macropore resins. Diethylaminoethyl sepharose (DEAE), a weak-basic anion-exchange resin, exhibited the highest bind capacity but inhibited the activity of RM lipase dramatically. On the contrary, RM lipase fixed with macropore resin D101 demonstrated the highest specific activity. Although immobilization with D101 didn't improve the activity of the enzyme, the thermostability of the immobilized enzyme elevated significantly. The immobilized RM lipase retained approximately 90% of its activity after 3-h incubation at 80 °C. Therefore, D101 was chosen as the supporting material of the target protein. CONCLUSION: The present study established a highly efficient strategy for large-scale preparation of RM lipase. This innovative technique not only provides high-purity RM lipase at a low cost but also has great potential as a platform for the preparation of lipases in the future.

In silico evaluation of the potential allergenicity of a fungal biomass from Rhizomucor pusillus for use as a novel food ingredient.

The world's hunger for novel food ingredients drives the development of safe, sustainable, and nutritious novel food products. For foods containing novel proteins, potential allergenicity of the proteins is a key safety consideration. One such product is a fungal biomass obtained from the fermentation of Rhizomucor pusillus. The annotated whole genome sequence of this strain was subjected to sequence homology searches against the AllergenOnline database (sliding 80-amino acid windows and full sequence searches). In a stepwise manner, proteins were designated as potentially allergenic and were further compared to proteins from commonly consumed foods and from humans. From the sliding 80-mer searches, 356 proteins met the conservative >35% Codex Alimentarius threshold, 72 of which shared ≥50% identity over the full sequence. Although matches were identified between R. pusillus proteins and proteins from allergenic food sources, the matches were limited to minor allergens from these sources, and they shared a greater degree of sequence homology with those from commonly consumed foods and human proteins. Based on the in silico analysis and a literature review for the source organism, the risk of allergenic cross-reactivity of R. pusillus is low.

Cutaneous mucormycosis infection owing to Rhizomucor variabilis presenting as recurrent lower limb ulceration and cellulitis in a diabetic patient.

Primary cutaneous mucormycosis is caused by environmental fungi and may complicate leg ulcers or traumatic wounds even in immunocompetent individuals. This case report highlights recurrent lower limb ulcers and cellulitis in a patient with type two diabetes mellitus, which was unresponsive to conventional antibiotic treatment. Histopathology revealed the diagnosis of cutaneous mucormycosis, and fungal cultures identified Rhizopus variabilis as the causative organism. Initial courses of oral azole antifungals yielded only partial response and he eventually required more aggressive treatment with i.v. amphotericin B and oral posaconazole. Good treatment outcomes for this condition require a high index of clinical suspicion, early histopathological and microbiological diagnosis, targeted systemic antifungal therapy, and surgical debridement if necessary.

Inside Out Computational Redesign of Cavities for Improving Thermostability and Catalytic Activity of Rhizomucor Miehei Lipase.

Cavities are created by hydrophobic interactions between residue side chain atoms during the folding of enzymes. Redesigning cavities can improve the thermostability and catalytic activity of the enzyme; however, the synergistic effect of cavities remains unclear. In this study, Rhizomucor miehei lipase (RML) was used as a model to explore volume fluctuation and spatial distribution changes of the internal cavities, which could reveal the roles of internal cavities in the thermostability and catalytic activity. We present an inside out cavity engineering (CE) strategy based on computational techniques to explore how changes in the volumes and spatial distribution of cavities affect the thermostability and catalytic activity of the enzyme. We obtained 12 single-point mutants, among which the melting temperatures (Tm) of 8 mutants showed an increase of more than 2°C. Sixteen multipoint mutations were further designed by spatial distribution rearrangement of internal cavities. The Tm of the most stable triple variant, with mutations including T21V (a change of T to V at position 21), S27A, and T198L (T21V/S27A/T198L), was elevated by 11.0°C, together with a 28.7-fold increase in the half-life at 65°C and a specific activity increase of 9.9-fold (up to 5,828 U mg-1), one of the highest lipase activities reported. The possible mechanism of decreased volumes and spatial rearrangement of the internal cavities improved the stability of the enzyme, optimizing the outer substrate tunnel to improve the catalytic efficiency. Overall, the inside out computational redesign of cavities method could help to deeply understand the effect of cavities on enzymatic stability and activity, which would be beneficial for protein engineering efforts to optimize natural enzymes. IMPORTANCE In the present study, R. miehei lipase, which is widely used in various industries, provides an opportunity to explore the effects of internal cavities on the thermostability and catalytic activity of enzymes. Here, we execute high hydrostatic pressure molecular dynamics (HP-MD) simulations to screen the critical internal cavity and reshape the internal cavities through site-directed mutation. We show that as the global internal cavity volume decreases, cavity rearrangement can improve the stability of the protein while optimizing the substrate channel to improve the catalytic efficiency. Our results provide significant insights into understanding the mechanism of action of the internal cavity. Our strategy is expected to be applied to other enzymes to promote increases in thermostability and catalytic activity.

Aggressive disseminated Rhizomucor pusillus infection in a Ph-like acute lymphoblastic leukemia patient: Early detection by cell-free DNA next-generation sequencing.

Disseminated Rhizomucor pusillus infection is a very rare but fatal complication in immunocompromised patients, because of aggressive clinical process with delayed diagnosis by routine laboratory tests. Recently, cell-free DNA next-generation sequencing (cfDNA NGS) has been used for the timely detection of infectious pathogens including mucormycosis. Herein, we described an 18-year-old male with Philadelphia-like acute lymphoblastic leukemia who received a timely diagnosis of R. pusillus infection by cell-free DNA next-generation sequencing, and confirmed by silver staining and qPCR on biopsy tissue. To the best of our knowledge, this was the first case of disseminated R. pusillus infection detected by cfDNA NGS and confirmed by histology in an adult leukemia patient. In addition, this case was supposed to be the most extensive R. pusillus infection diagnosed, involving the lung, skin, liver, kidney, spleen and brain, and the only one case who survived the infection had a favorable outcome through treatment with liposome amphotericin B sequential posaconazole. This case suggested that cfDNA NGS could be used to successfully detect rare pathogen infections, and this was especially important for R. pusillus because timely diagnosis and effective treatment could improve the prognosis of this kind of patient.

Kinetic Modeling, Thermodynamic Approach and Molecular Dynamics Simulation of Thermal Inactivation of Lipases from Burkholderia cepacia and Rhizomucor miehei.

The behavior against temperature and thermal stability of enzymes is a topic of importance for industrial biocatalysis. This study focuses on the kinetics and thermodynamics of the thermal inactivation of Lipase PS from B. cepacia and Palatase from R. miehei. Thermal inactivation was investigated using eight inactivation models at a temperature range of 40-70 °C. Kinetic modeling showed that the first-order model and Weibull distribution were the best equations to describe the residual activity of Lipase PS and Palatase, respectively. The results obtained from the kinetic parameters, decimal reduction time (D and tR), and temperature required (z and z') indicated a higher thermal stability of Lipase PS compared to Palatase. The activation energy values (Ea) also indicated that higher energy was required to denature bacterial (34.8 kJ mol-1) than fungal (23.3 kJ mol-1) lipase. The thermodynamic inactivation parameters, Gibbs free energy (ΔG#), entropy (ΔS#), and enthalpy (ΔH#) were also determined. The results showed a ΔG# for Palatase (86.0-92.1 kJ mol-1) lower than for Lipase PS (98.6-104.9 kJ mol-1), and a negative entropic and positive enthalpic contribution for both lipases. A comparative molecular dynamics simulation and structural analysis at 40 °C and 70 °C were also performed.

Investigation of Structural Features of Two Related Lipases and the Impact on Fatty Acid Specificity in Vegetable Fats.

One of the indispensable applications of lipases in modification of oils and fats is the possibility to tailor the fatty acid content of triacylglycerols (TAGs), to meet specific requirements from various applications in food, nutrition, and cosmetic industries. Oleic acid (C18:1) and stearic acid (C18:0) are two common long fatty acids in the side chain of triglycerides in plant fats and oils that have similar chemical composition and structures, except for an unsaturated bond between C9 and C10 in oleic acid. Two lipases from Rhizomucor miehei (RML) and Rhizopus oryzae (ROL), show activity in reactions involving oleate and stearate, and share high sequence and structural identity. In this research, the preference for one of these two similar fatty acid side chains was investigated for the two lipases and was related to the respective enzyme structure. From transesterification reactions with 1:1 (molar ratio) mixed ethyl stearate (ES) and ethyl oleate (EO), both RML and ROL showed a higher activity towards EO than ES, but RML showed around 10% higher preference for ES compared with ROL. In silico results showed that stearate has a less stable interaction with the substrate binding crevice in both RML and ROL and higher tendency to freely move out of the substrate binding region, compared with oleate whose structure is more rigid due to the existence of the double bond. However, Trp88 from RML which is an Ala at the identical position in ROL shows a significant stabilization effect in the substrate interaction in RML, especially with stearate as a ligand.

Efficient improvement of surface displayed lipase from Rhizomucor miehei in PichiaPink™ protease-deficient system.

Lipase from Rhizomucor miehei (RML) is a promising biocatalyst used in food industry, fine chemicals, and biodiesel production. Yeast surface display allows direct application of lipase in form of whole-cell biocatalyst, avoiding purification and immobilization process, but the protease of the host cell may affect the activity of displayed lipase. Herein, we used the protease-deficient Pichia pastoris, PichiaPink™ as host to display RML efficiently. RML gene, GCW21 gene and α-factor gene were co-cloned into plasmid pPink LC/HC and transformed into protease-deficient P. pastoris. After inducution expression for 96 h, the lipase activity of displayed RML reached 121.72 U/g in proteinase-A-deficient P. pastoris harboring high-copy plasmid, which exhibited 46.7% higher than recombinant P. pastoris without protease defect. Displayed RML occurred the maximum activity at pH 8.0 and 45 °C and the optimal substrate was p-nitrophenyl octanoate. Metal ions Li+, Na+, K+, and Mg2+ of 1-10 mM had activation towards displayed RML. Displayed RML was effectively improved in PichiaPink™ protease-deficient system, which may promote the further research and development for the industrial application of RML.

Dancing with oils - the interaction of lipases with different oil/water interfaces.

The use of enzymes as biocatalysts in industrial applications has received much attention during the last few years. Lipases are widely employed in the food and cosmetic industry, for the synthesis of novel biomaterials and as a greener solution for the treatment of waste cooking oils (WCO). The latter topic has been widely explored with the use of enzymes from several origins and types, for the treatment of different used and non-used cooking oils. The experimental conditions of such works are also quite broad, hampering the detailed understanding of the process. In this work we present a detailed characterization of the interaction of several commonly used lipases with different types of vegetal oils and food fats through coarse-grained molecular dynamics simulations. First, the molecular details of the oil/water (O/W) mixtures, namely at the O/W interface, are described. The O/W interface was found to be enriched in triglyceride molecules with higher polarity. Then, the interaction of lipases with oil mixtures is characterized from different perspectives, including the identification of the most important protein residues for this process. The lipases from Thermomyces lanuginosus (TLL), Rhizomucor miehei (RML) and Candida antarctica (CALB) were found to bind to the O/W interface in a manner that makes the protein binding site more available for the oil molecules. These enzymes were also found to efficiently bind to the O/W interface of all oil mixtures, which in addition to reactivity factors, may explain the efficient applicability of these enzymes to a large variety of edible oils and WCO.

Survival of thermophilic fungi in various preservation methods: A comparative study.

Thermophilic fungi have several biotechnological and industrial applications such as thermostable enzyme production, biodegradation, and tobacco processing, etc. Thermophilic fungi cannot survive at temperatures below 20 °C. Owing to their inability to grow at low temperatures, they are not stable, so stocking is very difficult. Although a large number of different storage methods are available and described, no method can be universally applied to all fungi. Thermophilic fungi present "heat-loving" characteristics, and therefore a new challenge for its preservation and there is no universal protocol for the preservation of thermophilic fungi. The aim of this study was to evaluate the viability, contamination and stability of thermophilic fungi stored under different preservation methods. In this work, 25 thermophilic fungal isolates of species Thermomyces thermophilus, Rhizomucor pusillus, Trichocladium griseum, Melanocarpus albomyces, Malbranchea cinnamomea, Thermothelomyces thermophilus, Thermothelomyces hinnuleus,Thermothielavioidesterrestris, Mycothermus thermophilus, Humicola insolens maintained constant sub-culturing at room temperature, +4 °C and +20 °C, lyophilization at +4 °C, freezing at -20 °C, freezing block at -20 °C and a new technique liquid preservation at room temperature for the periods ranging 5 years. We evaluated the effect of preservation methods by sub-culturing onto either sabouraud dextrose agar (SDA) or yeast extract soluble starch agar (YpSs) on growth, production and viability of spores and macro- and micromorphology. In this study, preservation methods for thermophilic fungi were investigated extensively for the first time and it is clearly shown that freezing block at -20 °C method and lyophilization were better methods for long-term preservation up to 5 years.

Thermophilic fungi in Araucaria Forest, Atlantic Forest Biome, Brazil.

Thermophilic fungi constitute an ecologically well-defined group, commonly found in environments wherever decomposition of organic matter takes place, making them self-heating. The importance of thermophilic fungus in ecosystems contrasts with the incompleteness of our understanding of the group's biogeography patterns, phylogenies and coevolution relationships. Actually, the lack of data about thermophilic fungi from the Brazil is a limiting factor that also contributes for this scenario. In order to reduce this gap of knowledge, we aimed to characterize thermophilic filamentous fungi in Araucaria Forest, Atlantic Forest biome. Species identification was achieved by using internal transcribed spacers (ITS) as molecular ribosomal markers. In total, 240 heat-tolerant fungal strains were isolated and identified as Thermothielavioides terrestris, Thielavia sp., Thermoascus crustaceus, Aspergillus fumigatus, Rhizomucor miehei, Rhizomucor pusillus, and Rhizopus microsporus. All thermophilic strains exhibited optimal growth at 45 °C. T. crustaceus, T. miehei e R. pusillus were the dominant species, with the frequencies of occurrence of 35.00%, 28.33% and 23.33%, respectively. Our data reveals the apparent diversity of the Neotropical realm and may serve as reference to future studies that will try to elucidate important aspects of group.

Crude glycerol impurities improve Rhizomucor miehei lipase production by Pichia pastoris.

Crude glycerol, a by-product of biodiesel production, was employed as the carbon source to produce lipase using Pichia pastoris. Under identical fermentation conditions, cell growth and lipase activity were improved using crude glycerol instead of pure glycerol. The impacts of crude glycerol impurities (methyl ester, grease, glycerol, methanol, and metal ions Na+, Ca2+, and Fe3+) on lipase production were investigated. Impurities accelerated P. pastoris entering the stationary phase. Na+, Ca2+, and grease in waste crude glycerol were the main factors influencing higher lipase activity. Through response surface optimization of Ca2+, Na+, and grease concentrations, lipase activity reached 1437 U/mL (15,977 U/mg), which was 2.5 times that of the control. This study highlights the economical and highly efficient valorization of crude glycerol, demonstrating its possible utilization as a carbon source to produce lipase by P. pastoris without pretreatment.

Promising Antidiabetic and Antimicrobial Agents Based on Fused Pyrimidine Derivatives: Molecular Modeling and Biological Evaluation with Histopathological Effect.

Diabetes is the most common metabolic disorder in both developing and non-developing countries, and a well-recognized global health problem. The WHO anticipates an increase in cases from 171 million in 2000 to 366 million by 2030. In the present study, we focus on the preparation of pyrimidine derivatives as potential antidiabetic and antimicrobial agents. Thein vivoeffect on total serum glucose concentration, cholesterol and antioxidant activity was assessed in adult male albino Wister rats and compared to the reference drug glimperide. Promising results were observed for compound 5. The histopathological study confirms that compound 5 results in significant activity with liver maintenance. The antimicrobial activities were evaluated against several bacterial strains such as Salmonella typhimurium ATCC 25566, Bacillus cereus, Escherichia coli NRRN 3008, Pseudomonas aeruginosa ATCC 10145, Staphylococcus aureus ATCC 6538and fungi such as Rhizopus oligosporus, Mucor miehei and Asperillus niger. Compounds 4 and 5 showed a good inhibition of the bacterial zone compared to the reference drug cephradine. Finally, we suggest protein targets for these drugs based on computational analysis, and infer their activities from their predicted modes of binding using molecular modeling. The molecular modeling for compounds 4 and 5 resulted in improved docking scores and hydrogen bonding. The docking studies are in good agreement with the in vitro and in vivo studies.

Fatal Meningoencephalitis From a Rhizomucor pusillus Infection in a Juvenile Magellanic Penguin (Spheniscus magellanicus).

A 7-month-old, male Magellanic penguin (Spheniscus magellanicus), housed in an outdoor exhibit, developed acute neurologic signs that progressed to death over 2 days. On gross examination, the bird had congested, edematous lungs, and cerebellar hemorrhage. Histologic examination identified granulomatous pneumonia and encephalitis, with thrombosis and eosinophilic, branching fungal hyphae that had invaded the meningeal vessel walls. Polymerase chain reaction identified the fungus in the brain as Rhizomucor pusillus, an uncommon cause of mucormycosis. This organism has previously been reported in respiratory, skeletal, and sino-orbital lesions of avian species. This clinical report describes meningoencephalitis associated with Rhizomucor pusillus in a penguin.

In Vitro Activity of Manogepix (APX001A) and Comparators against Contemporary Molds: MEC Comparison and Preliminary Experience with Colorimetric MIC Determination.

Manogepix (APX001A) is the active moiety of the drug candidate fosmanogepix (APX001), currently in clinical development for the treatment of invasive fungal infections. We compared manogepix EUCAST minimum effective concentrations (MECs) to MICs of five comparators and CLSI MECs and MICs by a colorimetric method against contemporary molds. EUCAST susceptibility testing was performed for 161 isolates. Interlaboratory and intermethod reproducibility were determined by comparison with published manogepix MECs. Colorimetric MICs (measuring metabolic activity) were evaluated using three Aspergillus fumigatus isolates and one Aspergillus flavus isolate with four inocula at 24 to 48 h of incubation and 1 to 3 h 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt (XTT)/menadione (MEN) exposure. Manogepix modal MECs (range in mg/liter) against Aspergillus species were 0.03 to 0.06 (0.008 to 0.125) and unaffected by itraconazole resistance. Manogepix was as active against two Fusarium isolates but inactive against Trichophyton interdigitale, Lichtheimia ramosa, and Rhizomucor pusillus isolates (MECs >0.5). Modal MEC/MICs were ≥3 2-fold dilutions apart without overlapping ranges comparing manogepix with amphotericin B, isavuconazole, and voriconazole against Aspergillus isolates. Manogepix and posaconazole MECs/MICs correlated for Aspergillus niger (Pearson's r = 0.711; P = 0.0044). The MEC at which 50% of the isolates tested are inhibited (MEC50), mode, and MEC90 values were within ±1 dilution in all cases compared with published EUCAST and CLSI data. The colorimetric method showed excellent agreement with the MECs when plates were inoculated with the lowest inoculum (1 × 102 CFU/ml to 2.5 × 102 CFU/ml), incubated for 24 h, and exposed for 1 to 3 h to XTT/MEN. Broad-spectrum in vitro activity of manogepix against clinically relevant molds was confirmed with excellent agreement across EUCAST and CLSI methods reported from experienced mycology laboratories. Colorimetric MIC determination warrants further investigation as a potential alternative that is less dependent on mycology expertise.

Osmolytes and membrane lipids in adaptive response of thermophilic fungus Rhizomucor miehei to cold, osmotic and oxidative shocks.

In contrast to mesophiles, in which levels of trehalose and phosphatidic acids (PA) increased only under heat shock (HS), in thermophiles trehalose and PA were predominant under optimal growth conditions. To study the role of trehalose protection in the adaptation of thermophiles to various stressors, the composition of osmolytes and membrane lipids in the thermophilic fungus Rhizomucor miehei was studied under cold (CS), osmotic (OS) and oxidative (OxS) shocks. CS resulted in no accumulation of glycerol in the mycelium, while the amount of trehalose decreased. The main lipid changes were the increase in the PA proportion with simultaneous decrease of sterols (St), the increase of the unsaturation degree of polar lipids and the decrease of the ergosterol proportion in total St. OS did not cause changes in the lipid composition, but led to the decrease of ergosterol proportion too. Despite the low ability of Mucorales to produce polyols, increase in the level of arabitol and glycerol was observed under OS. OxS led to the decrease of trehalose level and had no effect on the lipid composition. Thus, our results show the similarity (OS) and the difference (CS and OxS) between adaptation mechanisms of thermophiles and mesophiles.

One-pot cascade synthesis of benzopyrans and dihydropyrano[c]chromenes catalyzed by lipase TLIM.

Lipase TLIM was reported to be an efficient, commercially available and reusable catalyst for the Knoevenagel-Michael cascade reactions of aldehydes, malononitrile/ethyl cyanoacetate and 4-hydroxycoumarin/1, 3-cyclohexanedione/dimedone in aqueous DMSO. This methodology presents many superiorities such as simple procedure, mild reaction conditions, commercially available and reusable catalyst, high substrate applicability, the ability to be scaled up, and good to excellent yields.

Outbreaks of Mucorales and the Species Involved.

The order Mucorales is an ancient group of fungi classified in the subphylum Mucoromycotina. Mucorales are mainly fast-growing saprotrophs that belong to the first colonizers of diverse organic materials and represent a permanent part of the human environment. Several species are able to cause human infections (mucormycoses) predominantly in patients with impaired immune system, diabetes, or deep trauma. In this review, we compiled 32 reports on community- and hospital-acquired outbreaks caused by Mucorales. The most common source of mucoralean outbreaks was contaminated medical devices that are responsible for 40.7% of the outbreaks followed by contaminated air (31.3%), traumatic inoculation of soil or foreign bodies (9.4%), and the contact (6.2%) or the ingestion (6.2%) of contaminated plant material. The most prevalent species were Rhizopus arrhizus and R. microsporus causing 57% of the outbreaks. The genus Rhizomucor was dominating in outbreaks related to contaminated air while outbreaks of Lichtheimia species and Mucor circinelloides were transmitted by direct contact. Outbreaks with the involvement of several species are reported. Subtyping of strains revealed clonality in two outbreaks and no close relation in two other outbreaks. Based on the existing data, outbreaks of Mucorales can be caused by heterogeneous sources consisting of different strains or different species. Person-to-person transmission cannot be excluded because Mucorales can sporulate on wounds. For a better understanding and prevention of outbreaks, we need to increase our knowledge on the physiology, ecology, and population structure of outbreak causing species and more subtyping data.

Fine Modulation of the Catalytic Properties of Rhizomucor miehei Lipase Driven by Different Immobilization Strategies for the Selective Hydrolysis of Fish Oil.

Functional properties of each enzyme strictly depend on immobilization protocol used for linking enzyme and carrier. Different strategies were applied to prepare the immobilized derivatives of Rhizomucor miehei lipase (RML) and chemically aminated RML (NH2-RML). Both RML and NH2-RML forms were covalently immobilized on glyoxyl sepharose (Gx-RML and Gx-NH2-RML), glyoxyl sepharose dithiothreitol (Gx-DTT-RML and Gx-DTT-NH2-RML), activated sepharose with cyanogen bromide (CNBr-RML and CNBr-NH2-RML) and heterofunctional epoxy support partially modified with iminodiacetic acid (epoxy-IDA-RML and epoxy-IDA-NH2-RML). Immobilization varied from 11% up to 88% yields producing specific activities ranging from 0.5 up to 1.9 UI/mg. Great improvement in thermal stability for Gx-DTT-NH2-RML and epoxy-IDA-NH2-RML derivatives was obtained by retaining 49% and 37% of their initial activities at 70 °C, respectively. The regioselectivity of each derivative was also examined in hydrolysis of fish oil at three different conditions. All the derivatives were selective between cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) in favor of EPA. The highest selectivity (32.9 folds) was observed for epoxy-IDA-NH2-RML derivative in the hydrolysis reaction performed at pH 5 and 4 °C. Recyclability study showed good capability of the immobilized biocatalysts to be used repeatedly, retaining 50-91% of their initial activities after five cycles of the reaction.

Promiscuous enzyme-catalyzed cascade reaction in water: Synthesis of dicoumarol derivatives.

Lipase RMIM was firstly used as a promiscuous biocatalyst to catalyze the Knoevenagel-Michael cascade reactions of 4-hydroxycoumarin with aromatic, heterocyclic or aliphatic aldehydes to synthesize dicoumarol derivatives in water. Results showed that the adopted methodology could offer many advantages, such as mild reaction conditions, pure aqueous reaction system, wide substrate applicability, recyclable catalyst, excellent yields (81-98%), operational simplicity, and environmentally friendly reactions.