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1.
Brief Bioinform ; 24(3)2023 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-37114659

RESUMO

Cyclic AMP receptor proteins (CRPs) are important transcription regulators in many species. The prediction of CRP-binding sites was mainly based on position-weighted matrixes (PWMs). Traditional prediction methods only considered known binding motifs, and their ability to discover inflexible binding patterns was limited. Thus, a novel CRP-binding site prediction model called CRPBSFinder was developed in this research, which combined the hidden Markov model, knowledge-based PWMs and structure-based binding affinity matrixes. We trained this model using validated CRP-binding data from Escherichia coli and evaluated it with computational and experimental methods. The result shows that the model not only can provide higher prediction performance than a classic method but also quantitatively indicates the binding affinity of transcription factor binding sites by prediction scores. The prediction result included not only the most knowns regulated genes but also 1089 novel CRP-regulated genes. The major regulatory roles of CRPs were divided into four classes: carbohydrate metabolism, organic acid metabolism, nitrogen compound metabolism and cellular transport. Several novel functions were also discovered, including heterocycle metabolic and response to stimulus. Based on the functional similarity of homologous CRPs, we applied the model to 35 other species. The prediction tool and the prediction results are online and are available at: https://awi.cuhk.edu.cn/∼CRPBSFinder.


Assuntos
Proteína Receptora de AMP Cíclico , Proteínas de Escherichia coli , Proteína Receptora de AMP Cíclico/genética , Proteína Receptora de AMP Cíclico/química , Proteína Receptora de AMP Cíclico/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Sítios de Ligação/genética , Ligação Proteica/genética
2.
Nano Lett ; 24(18): 5550-5555, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38683946

RESUMO

Understanding and controlling exciton properties are important for the design of 2D semiconductors, such as monolayer transition metal dichalcogenides (TMDCs) and 2D halide perovskites (HPs). This paper demonstrates that the widespread strategy used for the exciton engineering of 2D HPs, based on dielectric mismatch, is flawed since dielectric mismatch has very little correlation with exciton properties. For monolayer TMDCs, however, the dielectric mismatch is shown to be more important.

3.
Small ; 20(8): e2303169, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37817375

RESUMO

The adsorption energy of the reaction intermediates has a crucial influence on the electrocatalytic activity. Ni-based materials possess high oxygen evolution reaction (OER) performance in alkaline, however too strong binding of *OH and high energy barrier of the rate-determining step (RDS) severely limit their OER activity. Herein, a facile strategy is shown to fabricate novel vertical nanorod-like arrays hybrid structure with the interface contact of S-doped Ni(OH)2 and CeO2 in situ grown on Ni foam (S-Ni(OH)2 /CeO2 /NF) through a one-pot route. The alcohol molecules oxidation reaction experiments and theoretical calculations demonstrate that S-doping and CeO2 -interfacing significantly modulate the binding energies of OER intermediates toward optimal value and reduce the energy barrier of the RDS, contributing to remarkable OER activity for S-Ni(OH)2 /CeO2 /NF with an ultralow overpotential of 196 mV at 10 mA cm-2 and long-term durability over 150 h for the OER. This work offers an efficient doping and interfacing strategy to tune the binding energy of the OER intermediates for obtaining high-performance electrocatalysts.

4.
Small ; 20(9): e2306945, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37863806

RESUMO

The Sabatier principle defines the essential criteria for an ideal catalyst in heterogeneous catalysis, while reaching the Sabatier optimum is still challenging in catalyst design. Herein, an elegant strategy is described to reach the Sabatier optimum of Ni electrocatalyst in CO2 reduction reaction (CO2 RR) by atomically Zn doping. The incorporation of 3% Zn single atom into Ni lattice leads to the moderate degrade of d-band center via Ni-Zn electronic coupling, which balances the bonding strengths of *COOH and *CO, resulting in a relative low energy barrier for CO2 activation while not being substantially poisoned by CO. Consequently, NiZn0.03 /C exhibits unique catalytic activity (jCO >100 mA cm-2 at -0.6 V), wide potential range for selective CO production (FECO >90% from -0.65 to -1.15 V), and outstanding long-term stability (FECO >90% during 85 h electrolysis at -0.85 V). The results provide valuable insights for the rational fabrication of superior non-noble bimetallic electrocatalysts in CO2 electroreduction.

5.
Small ; : e2403557, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38966886

RESUMO

It is a grand challenge to deep understanding of and precise control over functional sites for the rational design of highly efficient catalysts for methanol electrooxidation. Here, an L12-Pt2RhFe intermetallic catalyst with integrated functional components is demonstrated, which exhibits exceptional CO tolerance. The Pt2RhFe/C achieves a superior mass activity of 6.43 A mgPt -1, which is 2.23-fold and 3.53-fold higher than those of PtRu/C and Pt/C. Impressively, the Pt2RhFe/C exhibits a significant enhancement in durability owing to its high CO-tolerance and stability. Density functional theory calculations reveal that high performance of Pt2RhFe intermetallic catalyst arises from the synergistic effect: the strong OH binding energy (OHBE) at Fe sites induce stably adsorbed OH species and thus facilitate the dehydrogenation step of methanol via rapid hydrogen transfer, while moderate OHBE at Rh sites promote the formation of the transition state (Pt-CO···OH-Rh) with a low activation barrier for CO removal. This work provides new insights into the role of OH binding strength in the removal of CO species, which is beneficial for the rational design of highly efficient catalysts.

6.
Small ; 20(30): e2311927, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38429244

RESUMO

Designing materials with low exciton binding energy is an efficient way of improving the hydrogen production performance of COFs(Covalent Organic Frameworks. Here, it is demonstrated that the strategy of decorating bromine atoms on Pyene-based COFs can achieve elevated photocatalytic H2 evolution rates (HER = 13.61 mmol g-1h-1). Low-temperature fluorescence and time-resolved fluorescence spectroscopy (TRPL) indicate that the introduction of bromine atoms can significantly suppress charge recombination. DFT (Density Functional Theory) calculation clarified that the C atoms adjacent to Br are the active sites with a reduced energy barrier in the process of formatting H intermediate species (H*). The modification strategy of Br atoms in COF furnishes a new medium for exploiting exquisite photocatalysts.

7.
Small ; : e2404294, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-39148221

RESUMO

Metallic zinc exhibits immense potential as an anode material for aqueous rechargeable zinc batteries due to its high theoretical capacity, low redox potential, and inherent safety. However, practical applications are hindered by dendrite formation and poor cycling stability. Herein, a facile substitution reaction method is presented to fabricate a 3D leaf-like Cu@Zn composite anode. This unique architecture, featuring a 3D network of leaf-like Cu on a Zn foil surface, significantly reduces nucleation overpotential and facilitates uniform Zn plating/stripping, effectively suppressing dendrite growth. Notably, an alloy layer of CuZn5 forms in situ on the 3D Cu layer during cycling. DFT calculations reveal that this CuZn5 alloy possesses a lower Zn binding energy compared to both Cu and Zn metal, further promoting Zn plating/stripping and enhancing electrochemical kinetics. Consequently, the symmetric Cu@Zn electrode exhibits remarkable cycling stability, surpassing 1300 h at 0.5 mA cm-2 with negligible dendrite formation. Furthermore, full cells comprising Cu@Zn||VO2 exhibit superior capacity and rate performance compared to bare Zn anodes. This work provides a promising strategy for constructing highly stable and efficient Zn anodes for next-generation aqueous zinc batteries.

8.
Small ; 20(32): e2401489, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38661053

RESUMO

To mitigate the environmental impact of the improper disposal of spent LiFePO4 batteries and reduce resource waste, the development of LiFePO4 recycling technologies is of paramount importance. Meanwhile, olivine-structured NaFePO4 in sodium-ion batteries has received great attention, due to its high theoretical specific capacity of 154 mAh g-1 and excellent stability. However, olivine NaFePO4 only can be synthesized from olivine LiFePO4. Accordingly, in this proposal, developing the continuous flow electrochemical solid-liquid reactor-based metal ion insertion technology is to utilize the olivine FePO4, recycled from LiFePO4, and to synthesize NaFePO4. Additionally, by employing I- as the reducing agent, NaFePO4 is successfully synthesized with a discharge-specific capacity of 134 mAh g-1 at 0.1C and a remarkable capacity retention rate of 86.5% after 100 cycles at 0.2C. And the reasons for sodium deficiency in the synthesized NFP are elucidated through first-principles calculations. Furthermore, the kinetics of the solid-solution reaction 2 (Na2/3+ßPO4→ Na1-αFePO4) mechanism improve with cycling and are sensitive to temperature. Utilizing a minimal amount of reducing agent in the electrochemical reactor, NaFePO4 synthesis is successfully achieved. This innovative approach offers a new, cost-effective, and environmentally friendly strategy for preparing NaFePO4 from recycling LiFePO4.

9.
Chemistry ; 30(37): e202400838, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38874008

RESUMO

The hydroxide exchange membrane fuel cells (HEMFCs) are promising but lack of high-performance anode hydrogen oxidation reaction (HOR) electrocatalysts. The platinum group metals (PGMs) have the HOR activity in alkaline medium two to three orders of magnitude lower than those in acid, leading to the high required PGMs amount on anode to achieve high HEMFC performance. The mechanism study demonstrates the hydrogen binding energy of the catalyst determines the alkaline HOR kinetics, and the adsorbed OH and water on the catalyst surface promotes HOR. Iridium (Ir) has a unique advantage for alkaline HOR due to its similar hydrogen binding energy to Pt and enhanced adsorption of OH. However, the HOR activity of Ir/C is still unsatisfied in practical HEMFC applications. Further fine tuning the adsorption of the intermediate on Ir-based catalysts is of great significance to improve their alkaline HOR activity, which can be reasonably realized by structure design and composition regulation. In this concept, we address the current understanding about the alkaline HOR mechanism and summarize recent advances of Ir-based electrocatalysts with enhanced alkaline HOR activity. We also discuss the perspectives and challenges on Ir-based electrocatalysts in the future.

10.
Environ Sci Technol ; 2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38247403

RESUMO

The mobility and distribution of heavy metal ions (HMs) in aquatic environments are significantly influenced by humic acid (HA), which is ubiquitous. A quantitative understanding of the interaction mechanism underlying the adsorption and retention of HMs by HA is of vital significance but remains elusive. Herein, the interaction mechanism between HA and different types of HMs (i.e., Cd(II), Pb(II), arsenate, and chromate) was quantitatively investigated at the nanoscale. Based on quartz crystal microbalance with dissipation tests, the adsorption capacities of Pb(II), Cd(II), As(V), and Cr(VI) ionic species on the HA surface were measured as ∼0.40, ∼0.25, ∼0.12, and ∼0.02 nmol cm-2, respectively. Atomic force microscopy force results showed that the presence of Pb(II)/Cd(II) cations suppressed the electrostatic double-layer repulsion during the approach of two HA surfaces and the adhesion energy during separation was considerably enhanced from ∼2.18 to ∼5.05/∼4.18 mJ m-2. Such strong adhesion stems from the synergistic metal-HA complexation and cation-π interaction, as evidenced by spectroscopic analysis and theoretical simulation. In contrast, As(V)/Cr(VI) oxo-anions could form only weak hydrogen bonds with HA, resulting in similar adhesion energies for HA-HA (∼2.18 mJ m-2) and HA-As(V)/Cr(VI)-HA systems (∼2.26/∼1.96 mJ m-2). This work provides nanoscale insights into quantitative HM-HA interactions, improving the understanding of HMs biogeochemical cycling.

11.
Macromol Rapid Commun ; : e2400276, 2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-39031940

RESUMO

Lubricant-infused slippery surfaces have recently emerged as promising antifouling coatings, showing potential against proteins, cells, and marine mussels. However, a comprehensive understanding of the molecular binding behaviors and interaction strength of foulants to these surfaces is lacking. In this work, mussel-inspired chemistry based on catechol-containing chemicals including 3,4-dihydroxyphenylalanine (DOPA) and polydopamine (PDA) is employed to investigate the antifouling performance and repellence mechanisms of fluorinated-based slippery surface, and the correlated interaction mechanisms are probed using atomic force microscopy (AFM). Intermolecular force measurements and deposition experiments between PDA and the surface reveal the ability of lubricant film to inhibit the contact of PDA particles with the substrate. Moreover, the binding mechanisms and bond dissociation energy between a single DOPA moiety and the lubricant-infused slippery surface are quantitatively investigated employing single-molecule force spectroscopy based on AFM (SM-AFM), which reveal that the infused lubricant layer can remarkably influence the dissociation forces and weaken the binding strength between DOPA and underneath per-fluorinated monolayer surface. This work provides new nanomechanical insights into the fundamental antifouling mechanisms of the lubricant-infused slippery surfaces against mussel-derived adhesive chemicals, with important implications for the design of lubricant-infused materials and other novel antifouling platforms for various bioengineering and engineering applications.

12.
Environ Res ; : 119892, 2024 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-39222729

RESUMO

The abuse of amphetamine-type stimulants (ATSs) has caused irreversible harm to public safety and ecosystems. A novel polymerized deep eutectic solvent modified magnetic pomelo peel biochar (PMBC) was prepared, and the differences in adsorption of four abused amphetamine-type stimulants (ATSs: AMP, MAMP, MDA and MDMA) were due to varying hydrogen bonds quantities and strengths. PMBC showed excellent chemical reactivity to MDMA, with a maximum adsorption capacity of 926.13 µg·g-1, which was 3.25, 2.52 and 1.15 times higher than that of AMP, MAMP and MDA, respectively. Modern spectral analysis showed that there were a series of active centers (-COOH, -NH2 and -OH) on the PMBC, which could form hydrogen bond networks with the nitrogen and oxygen functional groups of ATSs. In various chemical environments: pH level (4-11), inorganic ion and organic matter (humic acid), PMBC maintained high activity towards four ATSs. Additionally, the quantum chemical calculations revealed that the methylenedioxy bridge of ATSs can increase the active sites, and the -NH- and -NH2 groups had different hydrogen bond formation capabilities, which together resulted in the adsorption order of PMBC on the four ATSs: MDMA>MDA>MAMP>AMP. Moreover, the hydrogen-bonding binding energies of several common hydrogen-bonding types were compared, including O-H····O, N-H····O/O-H····N and N-H···N. This study laid an empirical and theoretical foundation for the efficient capture of ATSs in water and contributed to the innovative design of materials.

13.
Mol Divers ; 2024 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-39096354

RESUMO

A novel series of quinolone-substituted 1,3,4-oxadiazole derivatives 4(a-l) have been designed and synthesized. The target compounds were investigated for their antibacterial activity against gram positive (Staphylococcus aureus, ATCC 25923, Enterococcus faecalis, ATCC 29212) and gram negative bacterium (Escherichia coli, ATCC 25922, Pseudomonas aeruginosa, ATCC 27853) for antifungal activity using (Candida albicans, ATCC 10231) and anti-inflammatory activity as COX-II inhibitors, respectively. The 1,3,4-oxadiazole functionality was introduced at C-6 position of pipemidic acid derivatives. IR, 1H NMR and Mass spectrometry techniques confirmed the structure of synthesized derivatives. The quinolone (pipemidic acid)-oxadiazole hybrid derivatives were effective against bacterial strains. When compared to ciprofloxacin (MIC 16 µg/mL), the compounds under consideration (4f, 4h, and 4k) showed significant antibacterial activity against all bacterial strains except Enterococcus faecalis, with MICs of 8 µg/mL. On the other hand, synthesized target compounds 4(a-l) did not respond well against Candida albicans fungal strain. The compound (4k) represents high % inhibition against COX-II. The compounds (4f, 4h and 4k) exhibited highest hydrogen bonding interaction with ARG57, ARG72, ARG78, LEU54 and MET16 target residues with a binding energy of - 8.4, - 8.6 and - 8.5 kcal/mol into the active pocket of DNA gyrase enzyme respectively even better in comparison to reference ligands. Based on the docking study, quinolone (pipemidic acid) oxadiazole hybrid structural ligands exhibited strong interaction at binding pockets of DNA gyrase enzyme.

14.
Mol Divers ; 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39017952

RESUMO

Dengue fever is a serious health hazard on a global scale and its primary causative agent is the dengue virus (DENV). The non-structural protein 1 (NS1) of DENV plays a pivotal role in pathogenesis. It is associated with several autoimmune events, endothelial cell apoptosis, and vascular leakage, which increase mainly during the critical phase of infection. In this study, important residues of the oligomerization domain of NS1 protein were identified by literature searches. Virtual screening has been conducted using the entire dataset of the DrugBank database and the potential small-molecule inhibitors against the NS1 protein have been chosen on the basis of binding energy values. This is succeeded by molecular dynamics (MD) simulations of the shortlisted compounds, ultimately giving rise to five compounds. These five compounds were further subjected to RAMD simulations by applying a random direction force of specific magnitude on the ligand center of mass in order to push the ligand out of the protein-binding pocket, for the quantitative estimation of their binding energy values to determine the interaction strength between protein and ligand which prevents ligand unbinding from its binding site, ultimately leading to the selection of three major compounds, DB00826 (Natamycin), DB11274 (Dihydro-alphaergocryptine), and DB11275 (Epicriptine), with the DB11274 having a role against idiopathic Parkinson's disease, and thus may have possible important roles in the prevention of dengue-associated Parkinsonism. These compounds may act as prospective drugs against dengue, by preventing the oligomerization of the NS1 protein, thereby preventing disease progression and pathogenesis.

15.
Proc Natl Acad Sci U S A ; 118(8)2021 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-33597304

RESUMO

Electrochemical oxidation of CH4 is known to be inefficient in aqueous electrolytes. The lower activity of methane oxidation reaction (MOR) is primarily attributed to the dominant oxygen evolution reaction (OER) and the higher barrier for CH4 activation on transition metal oxides (TMOs). However, a satisfactory explanation for the origins of such lower activity of MOR on TMOs, along with the enabling strategies to partially oxidize CH4 to CH3OH, have not been developed yet. We report here the activation of CH4 is governed by a previously unrecognized consequence of electrostatic (or Madelung) potential of metal atom in TMOs. The measured binding energies of CH4 on 12 different TMOs scale linearly with the Madelung potentials of the metal in the TMOs. The MOR active TMOs are the ones with higher CH4 binding energy and lower Madelung potential. Out of 12 TMOs studied here, only TiO2, IrO2, PbO2, and PtO2 are active for MOR, where the stable active site is the O on top of the metal in TMOs. The reaction pathway for MOR proceeds primarily through *CH x intermediates at lower potentials and through *CH3OH intermediates at higher potentials. The key MOR intermediate *CH3OH is identified on TiO2 under operando conditions at higher potential using transient open-circuit potential measurement. To minimize the overoxidation of *CH3OH, a bimetallic Cu2O3 on TiO2 catalysts is developed, in which Cu reduces the barrier for the reaction of *CH3 and *OH and facilitates the desorption of *CH3OH. The highest faradaic efficiency of 6% is obtained using Cu-Ti bimetallic TMO.

16.
Nano Lett ; 23(24): 11586-11592, 2023 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-38065566

RESUMO

Layered lead-halide perovskites have shown tremendous success as an active material for optoelectronics. This is attributed to the electronic structure of the inorganic sublattice and large exciton binding energies due to quantum and dielectric confinement. Expanding functionalities for applications that depend on free-carrier generation requires new material design routes to decrease the binding energy. Here we use electronic structure methods with model Bethe-Salpeter equation (BSE) to examine the contributions of the dielectric screening and charge-transfer excited-states to the exciton binding energy of phenylethylammonium (PEA2PbBr4) and naphthlethylammonium (NEA2PbBr4) lead-bromide perovskites. Our model BSE calculations show that NEA introduces hole acceptor states which impose charge-transfer character on the exciton along with larger dielectric screening. This substantially decreases the exciton binding compared to PEA. This result suggests the use of organic cations with high dielectric screening and hole acceptor states as a viable strategy for reducing exciton binding energies in two-dimensional halide perovskites.

17.
Int J Mol Sci ; 25(11)2024 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-38891954

RESUMO

While research has identified several inhibitors of the main protease (Mpro) of SARS-CoV-2, a significant portion of these compounds exhibit reduced activity in the presence of reducing agents, raising concerns about their effectiveness in vivo. Furthermore, the conventional biosafety level 3 (BSL-3) for cellular assays using viral particles poses a limitation for the widespread evaluation of Mpro inhibitor efficacy in a cell-based assay. Here, we established a BSL-1 compatible cellular assay to evaluate the in vivo potential of Mpro inhibitors. This assay utilizes mammalian cells expressing a tagged Mpro construct containing N-terminal glutathione S-transferase (GST) and C-terminal hemagglutinin (HA) tags and monitors Mpro autodigestion. Using this method, GC376 and boceprevir effectively inhibited Mpro autodigestion, suggesting their potential in vivo activity. Conversely, carmofur and ebselen did not exhibit significant inhibitory effects in this assay. We further investigated the inhibitory potential of selenoneine on Mpro using this approach. Computational analyses of binding energies suggest that noncovalent interactions play a critical role in facilitating the covalent modification of the C145 residue, leading to Mpro inhibition. Our method is straightforward, cost-effective, and readily applicable in standard laboratories, making it accessible to researchers with varying levels of expertise in infectious diseases.


Assuntos
Antivirais , Azóis , Proteases 3C de Coronavírus , Isoindóis , Compostos Organosselênicos , Prolina , SARS-CoV-2 , Antivirais/farmacologia , Antivirais/química , Humanos , SARS-CoV-2/efeitos dos fármacos , SARS-CoV-2/enzimologia , Compostos Organosselênicos/farmacologia , Compostos Organosselênicos/química , Isoindóis/farmacologia , Proteases 3C de Coronavírus/antagonistas & inibidores , Proteases 3C de Coronavírus/metabolismo , Azóis/farmacologia , Azóis/química , Prolina/análogos & derivados , Prolina/farmacologia , Prolina/química , Simulação de Acoplamento Molecular , Inibidores de Proteases/farmacologia , Inibidores de Proteases/química , Tratamento Farmacológico da COVID-19 , COVID-19/virologia , Células HEK293 , Lactamas , Leucina/análogos & derivados , Ácidos Sulfônicos
18.
Int J Mol Sci ; 25(4)2024 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-38397082

RESUMO

Brassicanate A sulfoxide, a secondary metabolite of broccoli, exhibited the inhibition of weed growth, but its mechanism of action on weeds remains unclear. To elucidate the mechanism by which brassicanate A sulfoxide suppresses weeds, this study explores the interaction between brassicanate A sulfoxide and the photosystem II D1 protein through molecular docking and molecular dynamics simulations. This research demonstrates that brassicanate A sulfoxide interacts with the photosystem II D1 protein by forming hydrogen bonds with Phe-261 and His-214. The successful expression of the photosystem II D1 protein in an insect cell/baculovirus system validated the molecular docking and dynamics simulations. Biolayer interferometry experiments elucidated that the affinity constant of brassicanate A sulfoxide with photosystem II was 2.69 × 10-3 M, suggesting that brassicanate A sulfoxide can stably bind to the photosystem II D1 protein. The findings of this study contribute to the understanding of the mode of action of brassicanate A sulfoxide and also aid in the development of natural-product-based photosynthesis-inhibiting herbicides.


Assuntos
Herbicidas , Herbicidas/química , Complexo de Proteína do Fotossistema II/metabolismo , Simulação de Acoplamento Molecular , Fotossíntese , Plantas Daninhas/metabolismo , Sulfóxidos
19.
Molecules ; 29(10)2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38792062

RESUMO

Combretastatins isolated from the Combretum caffrum tree belong to a group of closely related stilbenes. They are colchicine binding site inhibitors which disrupt the polymerization process of microtubules in tubulins, causing mitotic arrest. In vitro and in vivo studies have proven that some combretastatins exhibit antitumor properties, and among them, combretastatin A-4 is the most active mitotic inhibitor. In this study, a series of novel combretastatin A-4 analogs containing carboxylic acid, ester, and amide moieties were synthesized and their cytotoxic activity against six tumor cell lines was determined using sulforhodamine B assay. For the most cytotoxic compounds (8 and 20), further studies were performed. These compounds were shown to induce G0/G1 cell cycle arrest in MDA and A549 cells, in a concentration-dependent manner. Moreover, in vitro tubulin polymerization assays showed that both compounds are tubulin polymerization enhancers. Additionally, computational analysis of the binding modes and binding energies of the compounds with respect to the key human tubulin isotypes was performed. We have obtained a satisfactory correlation of the binding energies with the IC50 values when weighted averages of the binding energies accounting for the abundance of tubulin isotypes in specific cancer cell lines were computed.


Assuntos
Proliferação de Células , Desenho de Fármacos , Estilbenos , Moduladores de Tubulina , Tubulina (Proteína) , Humanos , Tubulina (Proteína)/metabolismo , Tubulina (Proteína)/química , Proliferação de Células/efeitos dos fármacos , Moduladores de Tubulina/farmacologia , Moduladores de Tubulina/síntese química , Moduladores de Tubulina/química , Estilbenos/farmacologia , Estilbenos/química , Estilbenos/síntese química , Linhagem Celular Tumoral , Antineoplásicos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Relação Estrutura-Atividade , Simulação de Acoplamento Molecular , Células A549 , Polimerização/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais
20.
Molecules ; 29(13)2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38999002

RESUMO

We examine the optical and electronic properties of a GaAs spherical quantum dot with a hydrogenic impurity in its center. We study two different confining potentials: (1) a modified Gaussian potential and (2) a power-exponential potential. Using the finite difference method, we solve the radial Schrodinger equation for the 1s and 1p energy levels and their probability densities and subsequently compute the optical absorption coefficient (OAC) for each confining potential using Fermi's golden rule. We discuss the role of different physical quantities influencing the behavior of the OAC, such as the structural parameters of each potential, the dipole matrix elements, and their energy separation. Our results show that modification of the structural physical parameters of each potential can enable new optoelectronic devices that can leverage inter-sub-band optical transitions.

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