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The serotonin transporter (SERT) is a member of the SLC6 neurotransmitter transporter family that mediates serotonin reuptake at presynaptic nerve terminals. SERT is the target of both therapeutic antidepressant drugs and psychostimulant substances such as cocaine and methamphetamines, which are small molecules that perturb normal serotonergic transmission by interfering with serotonin transport. Despite decades of studies, important functional aspects of SERT such as the oligomerization state of native SERT and its interactions with potential proteins remain unresolved. Here, we develop methods to isolate SERT from porcine brain (pSERT) using a mild, nonionic detergent, utilize fluorescence-detection size-exclusion chromatography to investigate its oligomerization state and interactions with other proteins, and employ single-particle cryo-electron microscopy to elucidate the structures of pSERT in complexes with methamphetamine or cocaine, providing structural insights into psychostimulant recognition and accompanying pSERT conformations. Methamphetamine and cocaine both bind to the central site, stabilizing the transporter in an outward open conformation. We also identify densities attributable to multiple cholesterol or cholesteryl hemisuccinate (CHS) molecules, as well as to a detergent molecule bound to the pSERT allosteric site. Under our conditions of isolation, we find that pSERT is best described as a monomeric entity, isolated without interacting proteins, and is ensconced by multiple cholesterol or CHS molecules.
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Estimulantes do Sistema Nervoso Central , Cocaína , Metanfetamina , Animais , Suínos , Proteínas da Membrana Plasmática de Transporte de Serotonina , Microscopia Crioeletrônica , Detergentes , Serotonina , Cocaína/farmacologia , Metanfetamina/farmacologiaRESUMO
Bacteria possess various receptors that sense different signals and transmit information to enable an optimal adaptation to the environment. A major limitation in microbiology is the lack of information on the signal molecules that activate receptors. Signals recognized by sensor domains are poorly reflected in overall sequence identity, and therefore, the identification of signals from the amino acid sequence of the sensor alone presents a challenge. Biogenic amines are of great physiological importance for microorganisms and humans. They serve as substrates for aerobic and anaerobic growth and play a role of neurotransmitters and osmoprotectants. Here, we report the identification of a sequence motif that is specific for amine-sensing sensor domains that belong to the Cache superfamily of the most abundant extracellular sensors in prokaryotes. We identified approximately 13,000 sensor histidine kinases, chemoreceptors, receptors involved in second messenger homeostasis and Ser/Thr phosphatases from 8,000 bacterial and archaeal species that contain the amine-recognizing motif. The screening of compound libraries and microcalorimetric titrations of selected sensor domains confirmed their ability to specifically bind biogenic amines. Mutants in the amine-binding motif or domains that contain a single mismatch in the binding motif had either no or a largely reduced affinity for amines. We demonstrate that the amine-recognizing domain originated from the universal amino acid-sensing Cache domain, thus providing insight into receptor evolution. Our approach enables precise "wet"-lab experiments to define the function of regulatory systems and therefore holds a strong promise to enable the identification of signals stimulating numerous receptors.
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Aminoácidos , Archaea , Humanos , Archaea/genética , Archaea/metabolismo , Aminoácidos/metabolismo , Proteínas de Bactérias/metabolismo , Bactérias/genética , Bactérias/metabolismo , Aminas Biogênicas/metabolismoRESUMO
Trace Amine Associated Receptor 1 (TAAR1) is a novel pharmaceutical target under investigation for the treatment of several neuropsychiatric conditions. TAAR1 single nucleotide variants (SNV) have been found in patients with schizophrenia and metabolic disorders. However, the frequency of variants in geographically diverse populations and the functional effects of such variants are unknown. In this study, we aimed to characterise the distribution of TAAR1 SNVs in five different WHO regions using the Database of Genotypes and Phenotypes (dbGaP) and conducted a critical computational analysis using available TAAR1 structural data to identify SNVs affecting ligand binding and/or functional regions. Our analysis shows 19 orthosteric, 9 signalling and 16 micro-switch SNVs hypothesised to critically influence the agonist induced TAAR1 activation. These SNVs may non-proportionally influence populations from discrete regions and differentially influence the activity of TAAR1-targeting therapeutics in genetically and geographically diverse populations. Notably, our dataset presented with orthosteric SNVs D1033.32N (found only in the South-East Asian Region and Western Pacific Region) and T1945.42A (found only in South-East Asian Region), and 2 signalling SNVs (V1253.54A/T2526.36A, found in African Region and commonly, respectively), all of which have previously demonstrated to influence ligand induced functions of TAAR1. Furthermore, bioinformatics analysis using SIFT4G, MutationTaster 2, PROVEAN and MutationAssessor predicted all 16 micro-switch SNVs are damaging and may further influence the agonist activation of TAAR1, thereby possibly impacting upon clinical outcomes. Understanding the genetic basis of TAAR1 function and the impact of common mutations within clinical populations is important for the safe and effective utilisation of novel and existing pharmacotherapies.
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Polimorfismo de Nucleotídeo Único , Receptores Acoplados a Proteínas G , Humanos , Receptores Acoplados a Proteínas G/genética , Polimorfismo de Nucleotídeo Único/genética , Relação Estrutura-Atividade , Genótipo , Ligantes , Receptores Associados a Traços de AminaRESUMO
Hydrolysis of N2O5 under tropospheric conditions plays a critical role in assessing the fate of O3, OH, and NOx in the atmosphere. However, its removal mechanism has not been fully understood, and little is known about the role of entropy. Herein, we propose a removal path of N2O5 on the water clusters/droplet with the existence of amine, which entails a low free-energy barrier of 4.46 and 3.76 kcal/mol on a water trimer and droplet, respectively, at room temperature. The free-energy barrier exhibits strong temperature dependence; a barrierless hydrolysis process of N2O5 at low temperature (≤150 K) is observed. By coupling constrained ab initio molecular dynamics (constrained AIMD) simulations with thermodynamic integration methods, we quantitively evaluated the entropic contributions to the free energy and compared NH3-, methylamine (MA)-, and dimethylamine (DMA)-promoted hydrolysis of N2O5 on water clusters and droplet. Our results demonstrate that methylation of NH3 stabilizes the product state and promotes hydrolysis of N2O5 by reducing the free-energy barriers. Furthermore, a quantitative analysis of the internal coordinate distribution of the reaction center and the relative position of surrounding species reveals that the significant entropic contribution primarily results from the ensemble effect of configurations observed in the AIMD simulations. Such an ensemble effect becomes more significant with more water molecules included. Lowering the temperature effectively minimizes the entropic contribution, making the hydrolysis more exothermic and barrierless. This study sheds light on the importance of the promoting effect of amines and the entropic effect on gas-phase hydrolysis reactions, which may have far-reaching implications in atmospheric chemistry.
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Aminas , Água , Dimetilaminas , Hidrólise , Metilaminas , Água/químicaRESUMO
Aqueous direct air capture (DAC) is a key technology toward a carbon negative infrastructure. Developing sorbent molecules with water and oxygen tolerance and high CO2 binding capacity is therefore highly desired. We analyze the CO2 absorption chemistries on amines, alkoxides, and phenoxides with density functional theory calculations, and perform inverse molecular design of the optimal sorbent. The alkoxides and phenoxides are found to be more suitable for aqueous DAC than amines thanks to their water tolerance (lower pKa prevents protonation by water) and capture stoichiometry of 1:1 (2:1 for amines). All three molecular systems are found to generally obey the same linear scaling relationship (LSR) between [Formula: see text] and [Formula: see text], since both CO2 and proton are bonded to the nucleophilic (alkoxy or amine) binding site through a majorly [Formula: see text] bonding orbital. Several high-performance alkoxides are proposed from the computational screening. Phenoxides have comparatively poorer correlation between [Formula: see text] and [Formula: see text], showing promise for optimization. We apply a genetic algorithm to search the chemical space of substituted phenoxides for the optimal sorbent. Several promising off-LSR candidates are discovered. The most promising one features bulky ortho substituents forcing the CO2 adduct into a perpendicular configuration with respect to the aromatic ring. In this configuration, the phenoxide binds CO2 and a proton using different molecular orbitals, thereby decoupling the [Formula: see text] and [Formula: see text]. The [Formula: see text] trend and off-LSR behaviors are then confirmed by experiments, validating the inverse molecular design framework. This work not only extensively studies the chemistry of the aqueous DAC, but also presents a transferrable computational workflow for understanding and optimization of other functional molecules.
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Dióxido de Carbono , Técnicas de Química Analítica , Óxidos , Água , Aminas , Dióxido de Carbono/química , Técnicas de Química Analítica/métodos , Óxidos/química , Prótons , Água/químicaRESUMO
Oxygen-mediated triplet-triplet annihilation upconversion (TTA-UC) quenching limits the application of such organic upconversion materials. Here, we report that the photooxidation of organic amines is an effective and versatile strategy to suppress oxygen-mediated upconversion quenching in both organic solvents and aqueous solutions. The strategy is based on the dual role of organic amines in photooxidation, i.e., as singlet oxygen scavengers and electron donors. Under photoexcitation, the photosensitizer sensitizes oxygen to produce singlet oxygen for the oxidation of alkylamine, reducing the oxygen concentration. However, photoinduced electron transfer among photosensitizers, organic amines, and oxygen leads to the production of superoxide anions that suppress TTA-UC. To observe oxygen-tolerating TTA-UC, we find that alkyl secondary amines can balance the production of singlet oxygen and superoxide anions. We then utilize polyethyleneimine (PEI) to synthesize amphiphilic polymers to encapsulate TTA-UC pairs for the formation of water-dispersible, ultrasmall, and multicolor-emitting TTA-UC nanoparticles.
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Multi-enzyme cascade catalysis has become an important technique for chemical reactions used in manufacturing and scientific study. In this research, we designed a four-enzyme integrated catalyst and used it to catalyse the deracemization reaction of cyclic chiral amines, where monoamine oxidase (MAO) catalyses the enantioselective oxidation of 1-methyl-1,2,3,4-tetrahydroisoquinoline (MTQ), imine reductase (IRED) catalyses the stereo selective reduction of 1-methyl-3,4-dihydroisoquinoline (MDQ), formate dehydrogenase (FDH) is used for the cyclic regeneration of cofactors, and catalase (CAT) is used for decomposition of oxidative reactions. The four enzymes were immobilized via polydopamine (PDA)-encapsulated dendritic organosilica nanoparticles (DONs) as carriers, resulting in the amphiphilic core-shell catalysts. The hydrophilic PDA shell ensures the dispersion of the catalyst in water, and the hydrophobic DON core creates a microenvironment with the spatial confinement effect of the organic substrate and the preconcentration effect to enhance the stability of the enzymes and the catalytic efficiency. The core-shell structure improves the stability and reusability of the catalyst and rationally arranges the position of different enzymes according to the reaction sequence to improve the cascade catalytic performance and cofactor recovery efficiency.
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Aminas , Monoaminoxidase , Polímeros , Aminas/química , Aminas/metabolismo , Monoaminoxidase/metabolismo , Monoaminoxidase/química , Polímeros/química , Polímeros/metabolismo , Formiato Desidrogenases/metabolismo , Formiato Desidrogenases/química , Catalase/química , Catalase/metabolismo , Indóis/química , Indóis/metabolismo , Estereoisomerismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Oxirredução , Nanopartículas/química , Biocatálise , Compostos de Organossilício/química , Oxirredutases/metabolismo , Oxirredutases/química , CatáliseRESUMO
Biocatalysis has emerged as a powerful alternative to traditional chemical methods, especially for asymmetric synthesis. As biocatalysts usually exhibit excellent chemical, regio- and enantioselectivity, they facilitate and simplify many chemical processes for the production of a broad range of products. Here, a new biocatalyst called, R-selective amine transaminases (R-ATAs), was obtained from Mycobacterium sp. ACS1612 (M16AT) using in-silico prediction combined with a genome and protein database. A two-step simple purification process could yield a high concentration of pure enzyme, suggesting that industrial application would be inexpensive. Additionally, the newly identified and characterized R-ATAs displayed a broad substrate spectrum and strong tolerance to organic solvents. Moreover, the synthetic applicability of M16AT has been demonstrated by the asymmetric synthesis of (R)-fendiline from of (R)-1-phenylethan-1-amine.
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Aminas , Mycobacterium , Aminas/química , Transaminases/metabolismo , Especificidade por Substrato , BiocatáliseRESUMO
We have developed and validated a novel LC-MS/MS method for simultaneously analyzing amino acids, biogenic amines, and their acetylated and methylated derivatives in plants. This method involves a one-step extraction of 2-5 mg of lyophilized plant material followed by fractionation of different biogenic amine forms and exploits an efficient combination of hydrophilic interaction chromatography (HILIC), reversed phase (RP) chromatography with pre-column derivatization, and tandem mass spectrometry. This approach enables high-throughput processing of plant samples, significantly reducing the time needed for analysis and its cost. We also present a new synthetic route for deuterium-labelled polyamines. The LC-MS/MS method was rigorously validated by quantifying levels of nitrogen-related metabolites in seedlings of seven plant species including Arabidopsis, maize, and barley, all of which are commonly used model organisms in plant science research. Our results revealed substantial variations in the abundance of these metabolites between species, developmental stages, and growth conditions, particularly for the acetylated and methylated derivatives and the various polyamine fractions. However, the biological relevance of these plant metabolites is currently unclear. Overall, this work contributes significantly to the field of plant science by providing a powerful analytical tool and setting the stage for future investigations into the functions of these nitrogen-related metabolites in plants.
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Herein, we disclose a facile and efficient electrochemical method for the dibromination of aryl amines by double functionalization of aromatic C(sp2 )-H (both para and ortho) under metal- and external oxidant-free conditions at room temperature for the first time. The reaction is demonstrated using 1,2-dibromoethane to dibrominate a wide range of N-substituted aryl amines in a simple setup with C(+)/Pt(-) electrodes under mild reaction conditions. This transformation proceeds smoothly with a broad substrate scope affording the valuable and versatile N-substituted 2,4-dibromoanilines in moderate to excellent yields with high regioselectivity. In this paired electrolysis, cathodic reduction of 1,2-DBE followed by anodic oxidation generates bromonium intermediates, which then couple with anilines to furnish the dibrominated products. It represents a distinctive approach to challenging redox-neutral reactions. The versatility of the electrochemical ortho-, para-dibromination was reflected by unique regioselectivities for challenging aryl amines and gram-scale electrosynthesis without the use of a stoichiometric oxidant or an activating agent.
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The reaction of the bicyclic silicon(I) ring compound Si4{N(SiMe3)Mes}4 1 with strong zwitterionic character and moderate sterical demand of the amido substituents with two equivalents of KC8 was investigated. This resulted in the unexpected abstraction of two amido substituents from 1 and additionally in dimerization to a dianionic Si8 cluster compound 2 with four unsubstituted silicon atoms and two [K([18]crown-6)]+ counter cations. Performing this reaction in the absence of [18]crown-6 results in release of only one amido substituent from 1 and dimerization to a dianionic Si8 cluster compound 3 with only two unsubstituted silicon atoms. This reaction with KC8 was repeated and trapping agents such as SiMe3Cl and tBuCl were added in-situ whereupon the second isolated homocyclic silylene 4 and a monoanionic hydride and tBu substituted Si8 cluster 5 with one unsubstituted silicon atom were isolated. Furthermore, 1 was reacted with KOtBu which resulted in the selective abstraction of one SiMe3 group and formation of the tetrahedral silanide 6 with one imido substituent bridging an edge of the tetrahedron.
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N-heterocyclic compounds have a broad range of applications and their selective synthesis is very appealing for the pharmaceutical and agrochemical industries. Herein we report the usage of the flavin-dependent nitroreductase BaNTR1 for the photoenzymatic synthesis of various anthranils and quinolines from retro-synthetically designed o-nitrophenyl-substituted carbonyl substrates, achieving high conversions (up to >99%) and good product yields (up to 96%). Whereas the effective production of anthranils required the inclusion of H2O2 in the reaction mixtures to accumulate the needed hydroxylamine intermediates, the formation of quinolines required the use of anaerobic or reducing conditions to efficiently generate the essential amine intermediates. Critical to our success was the high chemoselectivity of BaNTR1, performing selective reduction of the nitro group without reduction of the carbonyl moiety or the activated carbon-carbon double bond. The results highlight the usefulness of an innocuous chlorophyll- and nitroreductase-based photoenzymatic system for the tailored synthesis of diverse N-heterocycles from simple nitro compounds.
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We report a Cu-catalyzed oxidative coupling of aliphatic amines with benzylic and aliphatic boronic esters to give high value alkyl amines, products found widely in applications from medicinal chemistry to materials science. This operationally simple reaction, which can be performed on gram scale, runs under mild conditions and exhibits broad functional group tolerance. The terminal oxidant of the reaction is O2 from the air, avoiding the need for additional chemical oxidants. Investigation into the reaction mechanism suggests that the boronic ester is activated by an aminyl radical, formed through oxidation of the amine by the Cu catalyst, to give a key alkyl radical intermediate. To demonstrate its utility and potential for late-stage functionalization, we showcase the method as the final step in the total synthesis of a TRPV1 antagonist.
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Methylenedianiline (MDA) is a secondary, undesired, product of the glycolysis process of polyurethane (PU) scraps due to hydrolysis and pyrolysis side reactions. As an aromatic and carcinogen amine, MDA poses different problems in handling, transporting, and labelling recycled polyols derived from glycolysis, hindering the closure of PU recycling loop. Aiming to provide a solution to this issue, in this work different deaminating agents (DAs) were investigated with the purpose of analyzing their reactivity with MDA. A first part of the study was devoted to the analysis of MDA formation as a function of reaction time and catalyst concentration (potassium acetate) during glycolysis. It was observed that the amount of MDA increases almost linearly with the extent of PU depolymerization and catalyst content. Among the DAs analyzed 2-ethylhexyl glycidyl ether (2-EHGE), and acetic anhydride (Ac2 O) showed interesting performance, which allowed MDA content to be diminished below the limit for labelling prescription in 30 minutes. PU rigid foams were, therefore, synthesized from the corresponding recycled products and characterized in terms of thermal and mechanical performance. Ac2 O-deaminated polyols led to structurally unstable foams with poor compressive strength, while 2-EHGE-deaminated products allowed the production of foams with improved mechanical performance and unaltered thermal conductivity.
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A sustainable and scalable protocol for synthesizing variously functionalized sulfonamides, from amines and sulfonyl chlorides, has been developed using environmentally responsible and reusable choline chloride (ChCl)-based deep eutectic solvents (DESs). In ChCl/glycerol (1:2 mol mol-1) and ChCl/urea (1:2 mol mol-1), these reactions yield up to 97% under aerobic conditions at ambient temperature within 2-12 h. The practicality of the method is exemplified by the sustainable synthesis of an FFA4 agonist and a key building block en route to anti-Alzheimer drug BMS-299897. A subtle interplay of electronic effects and the solubility characteristics of the starting materials in the aforementioned DESs seem to be responsible for driving the reaction successfully over the hydrolysis of sulfonyl chlorides. The procedure's eco-friendliness is validated by quantitative metrics like the E-factor and the EcoScale, with products isolated by extraction or filtration after decantation.
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Anilines are core motifs in a variety of important molecules including medicines, materials and agrochemicals. We report a straightforward procedure that allows access to new chemical space of anilines via their para-C-H alkylation. The method utilizes commercially available catalytic H2 O â B(C6 F5 )3 and is highly selective for para-C-alkylation (over N-alkylation and ortho-C-alkylation) of anilines, with a wide scope in both the aniline substrates and alkene coupling partners. Readily available alkenes are used, and include new classes of alkene for the first time. The mild reaction conditions have allowed the procedure to be applied to the late-stage-functionalization of non-steroidal anti-inflammatory drugs (NSAIDs), including fenamic acids and diclofenac. The formed novel NSAID derivatives display improved anti-inflammatory properties over the parent NSAID structure.
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Alcenos , Compostos de Anilina , Alcenos/química , Compostos de Anilina/química , Alquilação , Anti-Inflamatórios não Esteroides , CatáliseRESUMO
This concept review describes the recent achievements on the Heyns rearrangement appeared in literature over the last decade and aims to provide the reader with a general overview of the fundamental synthetic advances in this research area.
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The application of biocatalysis has become essential in both academic and industrial domains for the asymmetric synthesis of chiral amines, and it serves as an alternative tool to transition-metal catalysis and complements traditional chemical methods. It relies on the swift expansion of available processes, primarily as a result of advanced tools for enzyme discovery, combined with high-throughput laboratory evolution techniques for optimizing biocatalysts. This concept paper explores the utilization of non-conventional media such as ether-type solvents, deep eutectic solvents, and micellar catalysis to enhance biocatalytic reactions for chiral amine synthesis. Each section focuses on the unique properties of these media, including their ability to stabilize enzymes, alter substrate solubility, and modulate enzyme selectivity. The paper aims to provide insights into how these innovative media can overcome traditional limitations, offering new avenues for sustainable and efficient chiral amine production through biocatalytic processes.
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The chemoselective [4+2] annulation/aromatization reactions between benzofuran-derived azadienes and N-Ts cyanamides are developed, affording a convenient method for synthesizing benzofuro[3,2-d]pyrimidin-2-amines under mild conditions. Herein, N-Ts cyanamides selectively participated in reactions absolutely via carbodiimide anion intermediates and the corresponding cyanamide anion intermediates derived products were not observed. The proposed chemoselective stepwise reaction mechanism was well supported by DFT calculations.
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A visible-light-induced strategy has been explored for the synthesis of naphtho[2,1-d]thiazol-2-amines through ortho-C-H sulfuration of 2-isocyanonaphthalenes with elemental sulfur and amines under external photocatalyst-free conditions. This three-component reaction, which utilizes elemental sulfur as the odorless sulfur source, molecular oxygen as the clean oxidant, and visible light as the clean energy source, provides a mild and efficient approach to construct a series of naphtho[2,1-d]thiazol-2-amines. Preliminary mechanistic studies indicated that visible-light-promoted photoexcitation of reaction intermediates consisting of thioureas and DBU might be involved in this transformation.