Ester Hydrolysis Reactions Research Articles

Mechanical force-switchable aqueous organocatalysis

Control over the catalytic activity of artificial catalytic systems in aqueous media is of high interest for biomimetic artificial catalysts. The activity of catalytic systems can be controlled via introducing stimuli-responsive feature in the structure of the catalytic systems. However, temperature, pH or light have been predominantly used as stimulus. Aqueous catalytic system whose activity can be turned ‘ON/OFF’ employing mechanical force has not been demonstrated. Here we show how catalytic activity of an aqueous catalytic system can be switched ‘ON/OFF’ via the application/ceasing ultrasound stimulus. We demonstrate that the accessibility of imidazole, a catalyst moiety, can be modulated via the presence/absence of the ultrasound stimulus, resulting temporal control over the rate of ester hydrolysis reactions in aqueous buffer solution. This generic approach enables using a large range of organocatalysts for the preparation of molecules and/or materials in aqueous media for their application to material science, and in biomedical field.

Preparation of Proline-Modified UIO−66 Nanomaterials and Investigation of Their Potential in Lipase Immobilization

Metal–organic frameworks (MOFs) are regarded as excellent carriers for immobilized enzymes due to their substantial specific surface area, high porosity, and easily tunable pore size. Nevertheless, the use of UIO−66 material is significantly limited in immobilized enzymes due to the absence of active functional groups on its surface. This study comprised the synthesis of UIO−66 and subsequent modification of the proline (Pro) on UIO−66 through post-synthetic modification. UIO−66 and UIO−66/Pro crystals were employed as matrices to immobilize Rhizopus oryzae lipase (ROL). The contact angle demonstrated that the introduction of Pro onto UIO−66 resulted in favorable conformational changes in the structure of ROL. The immobilized enzyme ROL@UIO−66/Pro, produced via the covalent-bonding method, exhibited greater activity (0.064715 U/mg (about 1.73 times that of the free enzyme)) and stability in the ester hydrolysis reaction. The immobilized enzymes ROL@UIO−66 (131.193 mM) and ROL@UIO−66/Pro (121.367 mM), which were synthesized using the covalent-bonding approach, exhibited a lower Km and higher substrate affinity compared to the immobilized enzyme ROL@UIO−66/Pro (24.033 mM) produced via the adsorption method. This lays a solid foundation for the industrialization of immobilized enzymes.

1-Naphthylacetic acid appended amino acids-based hydrogels: probing of the supramolecular catalysis of ester hydrolysis reaction

Natural amino acids and their derivatives are valuable ingredients for constructing various nanostructures that can show esterase-like activity. The co-assembly template, helical nanofibers and lysine play crucial role in ester hydrolysis reaction.

Sulfonated sucrose-derived carbon: efficient carbocatalysts for ester hydrolysis

A series of sulfonated carbon as efficient acid catalysts for ester hydrolysis reactions was prepared by simultaneous sulfonation and carbonization of sucrose with sulfosalicylic acid via hydrothermal carbonization.

Understanding The Mechanisms Of Catalytic Reactions On K10 Clay: A Comprehensive Study

Understanding The Mechanisms Of Catalytic Reactions On K10 Clay: A Comprehensive Study

Rapid mechanochemical production of biocomposites by encapsulating enzymes to zinc based-two metal organic frameworks (ZIF-8 and Zn-MOF-74) for enantioselective hydrolysis reaction of racemic Naproxen methyl ester

The mechanochemical encapsulation of enzymes during the synthesis of metal–organic frameworks (MOF) have been thought to be a natural, economical, new, and environmentally friendly step in synthesizing supported enzymatic catalysts. In this study, for the first time, a mechanochemical technique was employed to immobilize Candida rugosa lipase (CRL), and two zinc-based MOF types (Zn-MOF-74 and ZIF-8) were preferred. The enzyme kinetics and immobilization parameters (pH, temperature, thermal stability and reusability) of the prepared encapsulated enzymes (Zn-MOF-74@CRL and ZIF-8@CRL) were investigated. The prepared encapsulated enzymes were characterized by FTIR, SEM and XRD. It was observed that the catalytic activity of Zn-MOF-74 @CRL was six times higher than that of ZIF-8@CRL. After five reuses, the activities of Zn-MOF-74@CRL and ZIF-8@CRL were found to be 81% and 73% retained, respectively. After being subjected to 60 °C for 120 min, ZIF-8@CRL and Zn-MOF-74@CRL maintained their activities at 65% and 73%, respectively. The enantioselective hydrolysis reaction of racemic naproxen methyl ester was chosen as the model reaction. The results showed Zn-MOF-74@CRL possessed better enantioselectivity (E = 245) than ZIF-8@CRL (E = 136). This study demonstrated that it is possible to create biocatalysts with excellent catalytic properties for the pharmaceutical industry using MOFs produced by the mechanochemical method.

Degradation of a New Herbicide Florpyrauxifen-Benzyl in Water: Kinetics, Various Influencing Factors and Its Reaction Mechanisms.

Florpyrauxifen-benzyl is a novel herbicide used to control weeds in paddy fields. To clarify and evaluate its hydrolytic behavior and safety in water environments, its hydrolytic characteristics were investigated under varying temperatures, pH values, initial mass concentrations and water types, as well as the effects of 40 environmental factors such as microplastics (MPs) and disposable face masks (DFMs). Meanwhile, hydrolytic products were identified by UPLC-QTOF-MS/MS, and its hydrolytic pathways were proposed. The effects of MPs and DFMs on hydrolytic products and pathways were also investigated. The results showed that hydrolysis of florpyrauxifen-benzyl was a spontaneous process driven by endothermic, base catalysis and activation entropy increase and conformed to the first-order kinetics. The temperature had an obvious effect on hydrolysis rate under alkaline condition, the hydrolysis reaction conformed to Arrhenius formula, and activation enthalpy, activation entropy, and Gibbs free energy were negatively correlated with temperature. Most of environmental factors promoted hydrolysis of florpyrauxifen-benzyl, especially the cetyltrimethyl ammonium bromide (CTAB). The hydrolysis mechanism was ester hydrolysis reaction with a main product of florpyrauxifen. The MPs and DFMs did not affect the hydrolytic mechanisms but the hydrolysis rate. The results are crucial for illustrating and assessing the environmental fate and risks of florpyrauxifen-benzyl.

A covalent crosslinking strategy to construct a robust peptide-based artificial esterase.

Peptide-based artificial enzymes derived from the supramolecular assembly of short peptides have attracted growing attention in recent years. However, the stability of these artificial enzymes is still a problem since their noncovalent supramolecular structure is quite sensitive and frail under environmental conditions. In this study, we reported a covalent crosslinking strategy for the fabrication of a robust peptide-based artificial esterase. Inspired by the di-tyrosine bonds in many natural structural proteins, multi-tyrosines were designed into a peptide sequence with histidine as the catalytic residue for the ester hydrolysis reaction. Upon the photo-induced oxidation reaction, the short peptide YYHYY rapidly transferred into nanoparticle-shaped aggregates (CL-YYHYY) and displayed improved esterase-like catalytic activity than some previously reported noncovalent-based artificial esterases. Impressively, CL-YYHYY showed outstanding reusability and superior stability under high temperature, strong acid and alkaline and organic solvent conditions. This study provides a promising approach to improving the catalytic activity and stability of peptide-based artificial enzymes.

Structure and Mechanism of a Cold-Adapted Bacterial Lipase.

The structural origin of enzyme cold-adaptation has been the subject of considerable research efforts in recent years. Comparative studies of orthologous mesophilic–psychrophilic enzyme pairs found in nature are an obvious strategy for solving this problem, but they often suffer from relatively low sequence identity of the enzyme pairs. Small bacterial lipases adapted to distinctly different temperatures appear to provide an excellent model system for these types of studies, as they may show a very high degree of sequence conservation. Here, we report the first crystal structures of lipase A from the psychrophilic bacterium Bacillus pumilus, which confirm the high structural similarity to the mesophilic Bacillus subtilis enzyme, as indicated by their 81% sequence identity. We further employ extensive QM/MM calculations to delineate the catalytic reaction path and its energetics. The computational prediction of a rate-limiting deacylation step of the enzymatic ester hydrolysis reaction is verified by stopped-flow experiments, and steady-state kinetics confirms the psychrophilic nature of the B. pumilus enzyme. These results provide a useful benchmark for examining the structural basis of cold-adaptation and should now make it possible to disentangle the effects of the 34 mutations between the two enzymes on catalytic properties and thermal stability.

Contributions of Cathepsin A and Carboxylesterase 1 to the hydrolysis of Tenofovir Alafenamide in the Human Liver, and the Effect of CES1 Genetic Variation on Tenofovir Alafenamide Hydrolysis

The prodrug tenofovir alafenamide (TAF) is a first‐line antiviral agent for the treatment of chronic hepatitis B infection. TAF activation involves multiple steps, and the first step is an ester hydrolysis reaction catalyzed by hydrolases. This study was to determine the contributions of carboxylesterase 1 (CES1) and cathepsin A (CatA) to TAF hydrolysis in the human liver. Our in vitroincubation studies showed that both CatA and CES1 catalyzed TAF hydrolysis in a pH‐dependent manner. At their physiological pH environment, the activity of CatA (pH 5.2) was 700‐1000‐fold higher than that of CES1 (pH 7.2). Given that the hepatic protein expression of CatA was approximately 200‐fold lower than that of CES1, the contribution of CatA to TAF hydrolysis in the human liver was estimated to be much greater than that of CES1, which is contrary to the previous perception that CES1 is the primary hepatic enzyme hydrolyzing TAF. The findings were further supported by a TAF incubation study with the CatA inhibitor telaprevir and the CES1 inhibitor bis‐(p‐nitrophenyl) phosphate. Moreover, an in vitrostudy revealed that the CES1 variant G143E (rs71647871) is a loss‐of‐function variant for CES1‐mediated TAF hydrolysis. In summary, our results suggest that CatA may play a more important role in the hepatic activation of TAF than CES1. Additionally, TAF activation in the liver could be affected by CES1 genetic variation, but the magnitude of impact appears to be limited due to the major contribution of CatA to hepatic TAF activation.

Experimental study on physicochemical structure of different rank coals under acid solvent treatments and its effects on heat of gas adsorption

Physicochemical structure characteristics and its effects on the heat of gas adsorption are the foundation for coalbed methane (CBM) development. Herein, this paper selected different rank coals before and after acid treatments to analyze the relationship among nanopore structure, chemical functional groups and the heat of gas adsorption through low-temperature N2 adsorption, Fourier transform infrared spectroscopy (FTIR) and calorimetric tests. This enabled us to explore the effect of acid solvents on nanopore structure and functional groups, and finally reveal a coupling mechanism between physicochemical structure and gas adsorption. Results showed that the specific surface area of Brunauer-Emmett-Teller model (BET-SSA) and pore volume of Barret-Joyner-Halenda model (BJH-PV) decrease first and subsequently increase with increasing coal evolution before and after acid treatments. However, both pore structure parameters and fractal dimension show a decrease or an increase at different degrees under pore expansion and increase effects. On the other hand, after acid treatments, aliphatic structures evidently decrease and aromatic structures relatively increase. For oxygen-containing functional groups affected by ester hydrolysis and Fourier reaction, more carboxyl and hydroxyl groups appear but ether groups reduce. This suggests that acid treatment is actually accompanied by more physicochemical changes. Then, according to its physicochemical response, less aliphatic structures and more aromatic structures significantly contribute to appear more micropores. However, a non-significant effect of aliphatic structure on gas adsorption is observed, while micropores, aromatic structure and oxygen-containing groups give a positive effect on gas adsorption.

Synthesis and application of a novel monomer 5-(1-Pyrrolidinyl)-1,3-benzenedicarbonyl dichloride in membranes

Developing novel monomers used for aromatic polyamide membranes is one of the promising modifications to tailor the membranes more efficient. Acyl chloride-based compound as the organic phase reactive monomer is vital to the fabrication of membranes. This study focuses on designing and synthesizing a novel acyl chloride monomer 5-(1-pyrrolidinyl)-1,3-benzenedicarbonyl dichloride (PIPC) based on the purpose of improving membrane permeability and anti-fouling, and preliminarily verify its feasibility for the synthesis of aromatic polyamide membranes. PIPC monomer with a rigid pyrrolidinyl group (–NC4H8) was synthesized from three steps of N-alkylation, ester hydrolysis and acylation reaction successively. IR and 1HNMR spectra were employed to demonstrate the successful synthesis of PIPC. The application of PIPC in the membrane field was also implemented via using PIPC alone as the organic phase reactive monomer, the first/second organic phase reactive monomer, and PIPC and trimesoyl chloride (TMC) together act as the organic phase reactive monomer to react with m-phenylenediamine (MPD) by interfacial polymerization (IP). The MPD-PIPC-TMC membrane prepared by PIPC as the first organic phase reactive monomer exhibited the highest water flux (27.89 ​L ​m−2 ​h−1), with the increase of 36.8% than the MPD-TMC membrane (20.38 ​L ​m−2 ​h−1), while maintaining similar salt rejection. The PIPC with a rigid pyrrolidinyl group was demonstrated to be a promising organic phase monomer for further synthesizing high permeability aromatic polyamide membrane, which showed great application prospects in the field of membrane industry.

Contributions of Cathepsin A and Carboxylesterase 1 to the Hydrolysis of Tenofovir Alafenamide in the Human Liver, and the Effect of CES1 Genetic Variation on Tenofovir Alafenamide Hydrolysis.

The prodrug tenofovir alafenamide (TAF) is a first-line antiviral agent for the treatment of chronic hepatitis B infection. TAF activation involves multiple steps, and the first step is an ester hydrolysis reaction catalyzed by hydrolases. This study was to determine the contributions of carboxylesterase 1 (CES1) and cathepsin A (CatA) to TAF hydrolysis in the human liver. Our in vitro incubation studies showed that both CatA and CES1 catalyzed TAF hydrolysis in a pH-dependent manner. At their physiologic pH environment, the activity of CatA (pH 5.2) was approximately 1,000-fold higher than that of CES1 (pH 7.2). Given that the hepatic protein expression of CatA was approximately 200-fold lower than that of CES1, the contribution of CatA to TAF hydrolysis in the human liver was estimated to be much greater than that of CES1, which is contrary to the previous perception that CES1 is the primary hepatic enzyme hydrolyzing TAF. The findings were further supported by a TAF incubation study with the CatA inhibitor telaprevir and the CES1 inhibitor bis-(p-nitrophenyl) phosphate. Moreover, an in vitro study revealed that the CES1 variant G143E (rs71647871) is a loss-of-function variant for CES1-mediated TAF hydrolysis. In summary, our results suggest that CatA may play a more important role in the hepatic activation of TAF than CES1. Additionally, TAF activation in the liver could be affected by CES1 genetic variation, but the magnitude of impact appears to be limited due to the major contribution of CatA to hepatic TAF activation. SIGNIFICANCE STATEMENT: Contrary to the general perception that carboxylesterase 1 (CES1) is the major enzyme responsible for tenofovir alafenamide (TAF) hydrolysis in the human liver, the present study demonstrated that cathepsin A may play a more significant role in TAF hepatic hydrolysis. Furthermore, the CES1 variant G143E (rs71647871) was found to be a loss-of-function variant for CES1-mediated TAF hydrolysis.

Syntheses of benzhydryl 2-propanoyl-functionalized trithiocarbonates and its use as chain transfer agents in the RAFT polymerization of styrene

Abstract The preparation of three new benzhydryl 2-propanoyl-functionalized trithiocarbonate RAFT agents, benzhydryl 2-(ethylsulfanylthiocarbonylsulfanyl)propanoate, benzhydryl 2-(butylsulfanylthiocarbonylsulfanyl)propanoate, benzhydryl 2-(dodecylsulfanylthiocarbonylsulfanyl)propanoate is described. The RAFT polymerization of styrene, mediated by the appropriate benzhydryl 2-(alkylsulfanylthiocarbonylsulfanyl)propanoate as the chain transfer agent, with AIBN as initiator at 70 0C, proceeds via reversible-deactivation radical polymerization processes to produce the corresponding α-benzhydryl 2-propanoyl polystyrene derivative, with the benzhydryl ester group introduced at the α-terminus of the polymer chain. Polymerization kinetics measurements show that each RAFT polymerization reaction follows first order rate kinetics with respect to percentage monomer consumption and the number average molecular weights of the functionalized polymers increase linearly with the percentage monomer conversion to produce functionalized polymers with narrow molecular weight distributions. The percentage monomer conversion with time for each polymerization reaction was monitored by 1H NMR spectroscopy by evaluating the consumption of styrene with respect to polymerization time. Post-RAFT polymerization chain end modification of α-benzhydryl 2-propanoyl-functionalized polystyrene by the acid catalyzed ester hydrolysis reactions with concentrated sulfuric acid afforded the corresponding α-carboxyl functionalized polystyrene derivative, with the retention of the thiocarbonylthio moiety at the ω-terminus of the polymer chain. The benzhydryl 2-propanoyl-functionalized trithiocarbonate chain transfer agents and the different functionalized polystyrene derivatives were characterized by 1H NMR, 13C NMR and FTIR spectroscopy, size exclusion chromatography, thin layer chromatography and mass spectrometry measurements.

The role of activated carbon nanoparticles on hydro-degumming non-edible vegetable oils

This study aims to assess the role of activated carbon nanoparticles in hydro-degumming non-edible vegetable oils. Bamboo Activated Carbon Nanoparticles (BAC-NPs) is added to oils in degumming process. Characterizations revealed mesoporous structures with specific surface area 673.298 m2/g, positive surface charge, aromatic ring cluster, and increased hydrophilicity. Magnetic moment induced by delocalized electrons in aromatic ring cluster of BAC-NPs works towards paramagnetic negatively charged oxygen around the phosphate head group of phospholipid molecule. It also works towards water molecules, changes water proton spin isomer from para to ortho, decreases intramolecular energy in water, facilitates base-promoted ester hydrolysis reaction. These phenomena, combined with heat energy and centrifugation force, trigger bonds disruption within phospholipid molecule, lead to a higher probability of phosphate head group detachment off the phospholipid molecule. As a result, there is a large reduction in phosphorus concentration (around 95%) and a slight improvement in viscosity and calorific value in treated oils.

Revisiting Jatropha curcas Monomeric Esterase: A Dienelactone Hydrolase Compatible with the Electrostatic Catapult Model.

Jatropha curcas contains seeds with a high oil content, suitable for biodiesel production. After oil extraction, the remaining mass can be a rich source of enzymes. However, data from the literature describing physicochemical characteristics for a monomeric esterase from the J. curcas seed did not fit the electrostatic catapult model for esterases/lipases. We decided to reevaluate this J. curcas esterase and extend its characterization to check this apparent discrepancy and gain insights into the enzyme’s potential as a biocatalyst. After anion exchange chromatography and two-dimensional gel electrophoresis, we identified the enzyme as belonging to the dienelactone hydrolase family, characterized by a cysteine as the nucleophile in the catalytic triad. The enzyme displayed a basic optimum hydrolysis pH of 9.0 and an acidic pI range, in contrast to literature data, making it well in line with the electrostatic catapult model. Furthermore, the enzyme showed low hydrolysis activity in an organic solvent-containing medium (isopropanol, acetonitrile, and ethanol), which reverted when recovering in an aqueous reaction mixture. This enzyme can be a valuable tool for hydrolysis reactions of short-chain esters, useful for pharmaceutical intermediates synthesis, due to both its high hydrolytic rate in basic pH and its stability in an organic solvent.

New derivatives of the iridoid specioside from fungal biotransformation.

Iridoids are widely found from species of Bignoniaceae family and exhibit several biological activities, such as anti-inflammatory, antimicrobial, antioxidant, and antitumor. Specioside is an iridoid found from Tabebuia species, mainly in Tabebuia aurea. Thus, here fungus-mediated biotransformation of the iridoid specioside was investigated by seven fungi. The fungus-mediated biotransformation reactions resulted in a total of nineteen different analogs by fungus Aspergillus niger, Aspergillus flavus, Aspergillus japonicus, Aspergillus terreus, Aspergillus niveus, Penicillium crustosum, and Thermoascus aurantiacus. Non-glycosylated specioside was the main metabolite observed. The other analogs were yielded from ester hydrolysis, hydroxylation, methylation, and hydrogenation reactions. The non-glycosylated specioside and coumaric acid were yielded by all fungi-mediated biotransformation. Thus, fungus applied in this study showed the ability to perform hydroxylation and glycosidic, as well as ester hydrolysis reactions from glycosylated iridoid. KEY POINTS: • The biotransformation of specioside by seven fungi yielded nineteen analogs. • The non-glycosylated specioside was the main analog obtained. • Ester hydrolysis, hydroxylation, methylation, and hydrogenation reactions were observe.

Efficiency of Lithium Cations in Hydrolysis Reactions of Esters in Aqueous Tetrahydrofuran.

Lithium cations were observed to accelerate the hydrolysis of esters with hydroxides (KOH, NaOH, LiOH) in a water/tetrahydrofuran (THF) two-phase system. Yields in the hydrolysis of substituted benzoates and aliphatic esters using the various hydroxides were compared, and the effects of the addition of lithium salt were examined. Moreover, it was presumed that a certain amount of LiOH was dissolved in THF by the coordination of THF with lithium cation and hydrolyzed esters even in the THF layer, as in the reaction by a phase-transfer catalyst.

Enantioselective epoxidation by the chiral auxiliary approach: Asymmetric total synthesis of (+)‐Ambrisentan

AbstractEnantioselective and a highly concise total synthesis of Ambrisentan are described. The chiral auxiliary controlled enantioselective epoxidation (Azerad protocol), photochemical regioselective epoxide opening, and base mediated ester hydrolysis reactions are the key reactions.

β-Carboline-Based pH Fluorescent Probe and Its Application for Monitoring Enzymatic Ester Hydrolysis.

A novel pH-activatable fluorescent probe, 1-(propan-2-yl)-9H-pyrido[3,4-b]indole-3-carboxylic acid (L-1), based on β-carboline derivatives, has been developed, which displays significant fluorescent response toward pH variation with high selectivity, good photo-stability and favorable pKa value. Moreover, L-1 can dynamically monitor the release of protons during ester hydrolysis reaction in consistent with enzymatic kinetics manner.