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1.
Int J Mol Sci ; 25(9)2024 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-38731806

RESUMEN

This study reveals a new non-covalent interaction called a π-hole halogen bond, which is directional and potentially non-linear compared to its sister analog (σ-hole halogen bond). A π-hole is shown here to be observed on the surface of halogen in halogenated molecules, which can be tempered to display the aptness to form a π-hole halogen bond with a series of electron density-rich sites (Lewis bases) hosted individually by 32 other partner molecules. The [MP2/aug-cc-pVTZ] level characteristics of the π-hole halogen bonds in 33 binary complexes obtained from the charge density approaches (quantum theory of intramolecular atoms, molecular electrostatic surface potential, independent gradient model (IGM-δginter)), intermolecular geometries and energies, and second-order hyperconjugative charge transfer analyses are discussed, which are similar to other non-covalent interactions. That a π-hole can be observed on halogen in halogenated molecules is substantiated by experimentally reported crystals documented in the Cambridge Crystal Structure Database. The importance of the π-hole halogen bond in the design and growth of chemical systems in synthetic chemistry, crystallography, and crystal engineering is yet to be fully explicated.


Asunto(s)
Halógenos , Electricidad Estática , Halógenos/química , Modelos Moleculares , Teoría Cuántica , Electrones , Termodinámica , Bases de Lewis/química , Halogenación
2.
Int J Mol Sci ; 25(9)2024 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-38731989

RESUMEN

Drug candidates must undergo thermal evaluation as early as possible in the preclinical phase of drug development because undesirable changes in their structure and physicochemical properties may result in decreased pharmacological activity or enhanced toxicity. Hence, the detailed evaluation of nitrogen-rich heterocyclic esters as potential drug candidates, i.e., imidazolidinoannelated triazinylformic acid ethyl esters 1-3 (where R1 = 4-CH3 or 4-OCH3 or 4-Cl, and R2 = -COOC2H5) and imidazolidinoannelated triazinylacetic acid methyl esters 4-6 (where R1 = 4-CH3 or 4-OCH3 or 4-Cl, and R2 = -CH2COOCH3)-in terms of their melting points, melting enthalpy values, thermal stabilities, pyrolysis, and oxidative decomposition course-has been carried out, using the simultaneous thermal analysis methods (TG/DTG/DSC) coupled with spectroscopic techniques (FTIR and QMS). It was found that the melting process (documented as one sharp peak related to the solid-liquid phase transition) of the investigated esters proceeded without their thermal decomposition. It was confirmed that the melting points of the tested compounds increased in relation to R1 and R2 as follows: 2 (R1 = 4-OCH3; R2 = -COOC2H5) < 6 (R1 = 4-Cl; R2 = -CH2COOCH3) < 5 (R1 = 4-OCH3; R2 = -CH2COOCH3) < 3 (R1 = 4-Cl; R2 = -COOC2H5) < 1 (R1 = 4-CH3; R2 = -COOC2H5) < 4 (R1 = 4-CH3; R2 = -CH2COOCH3). All polynitrogenated heterocyclic esters proved to be thermally stable up to 250 °C in inert and oxidising conditions, although 1-3 were characterised by higher thermal stability compared to 4-6. The results confirmed that both the pyrolysis and the oxidative decomposition of heterocyclic ethyl formates/methyl acetates with para-substitutions at the phenyl moiety proceed according to the radical mechanism. In inert conditions, the pyrolysis process of the studied molecules occurred with the homolytic breaking of the C-C, C-N, and C-O bonds. This led to the emission of alcohol (ethanol in the case of 1-3 or methanol in the case of 4-6), NH3, HCN, HNCO, aldehydes, CO2, CH4, HCl, aromatics, and H2O. In turn, in the presence of air, cleavage of the C-C, C-N, and C-O bonds connected with some oxidation and combustion processes took place. This led to the emission of the corresponding alcohol depending on the analysed class of heterocyclic esters, NH3, HCN, HNCO, aldehydes, N2, NO/NO2, CO, CO2, HCl, aromatics, and H2O. Additionally, after some biological tests, it was proven that all nitrogen-rich heterocyclic esters-as potential drug candidates-are safe for erythrocytes, and some of them are able to protect red blood cells from oxidative stress-induced damage.


Asunto(s)
Ésteres , Compuestos Heterocíclicos , Nitrógeno , Ésteres/química , Nitrógeno/química , Compuestos Heterocíclicos/química , Estabilidad de Medicamentos , Termodinámica , Espectroscopía Infrarroja por Transformada de Fourier , Pirólisis
3.
Protein Sci ; 33(6): e5003, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38747380

RESUMEN

Extremophile organisms have adapted to extreme physicochemical conditions. Halophilic organisms, in particular, survive at very high salt concentrations. To achieve this, they have engineered the surface of their proteins to increase the number of short, polar and acidic amino acids, while decreasing large, hydrophobic and basic residues. While these adaptations initially decrease protein stability in the absence of salt, they grant halophilic proteins remarkable stability in environments with extremely high salt concentrations, where non-adapted proteins unfold and aggregate. The molecular mechanisms by which halophilic proteins achieve this, however, are not yet clear. Here, we test the hypothesis that the halophilic amino acid composition destabilizes the surface of the protein, but in exchange improves the stability in the presence of salts. To do that, we have measured the folding thermodynamics of various protein variants with different degrees of halophilicity in the absence and presence of different salts, and at different pH values to tune the ionization state of the acidic amino acids. Our results show that halophilic amino acids decrease the stability of halophilic proteins under mesophilic conditions, but in exchange improve salt-induced stabilization and solubility. We also find that, in contrast to traditional assumptions, contributions arising from hydrophobic effect and preferential ion exclusion are more relevant for haloadaptation than electrostatics. Overall, our findings suggest a trade-off between folding thermodynamics and halophilic adaptation to optimize proteins for hypersaline environments.


Asunto(s)
Estabilidad Proteica , Electricidad Estática , Termodinámica , Pliegue de Proteína , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas
4.
J Chem Phys ; 160(17)2024 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-38748013

RESUMEN

Several enhanced sampling techniques rely on the definition of collective variables to effectively explore free energy landscapes. The existing variables that describe the progression along a reactive pathway offer an elegant solution but face a number of limitations. In this paper, we address these challenges by introducing a new path-like collective variable called the "deep-locally non-linear-embedding," which is inspired by principles of the locally linear embedding technique and is trained on a reactive trajectory. The variable mimics the ideal reaction coordinate by automatically generating a non-linear combination of features through a differentiable generalized autoencoder that combines a neural network with a continuous k-nearest neighbor selection. Among the key advantages of this method is its capability to automatically choose the metric for searching neighbors and to learn the path from state A to state B without the need to handpick landmarks a priori. We demonstrate the effectiveness of DeepLNE by showing that the progression along the path variable closely approximates the ideal reaction coordinate in toy models, such as the Müller-Brown potential and alanine dipeptide. Then, we use it in the molecular dynamics simulations of an RNA tetraloop, where we highlight its capability to accelerate transitions and estimate the free energy of folding.


Asunto(s)
Aprendizaje Profundo , Simulación de Dinámica Molecular , ARN/química , Termodinámica , Dipéptidos/química
5.
Sci Rep ; 14(1): 11060, 2024 05 14.
Artículo en Inglés | MEDLINE | ID: mdl-38744931

RESUMEN

In this paper the photobiomodulation on isolated mitochondria of bovine liver is studied as a thermodynamic process of conversion of energy. This analysis is conducted by considering a particular set-up for the photobiomodulation experiments of interest. It allows, in particular, the computation of the electromagnetic field and the related energetic quantities in the stimulated organelles. The measurements of the excess of biochemical power density produced by the illuminated mitochondria are performed at regular time intervals after the experiments. The calculations and the measurements finally allow us to obtain the first results on the efficiency of the process of conversion of electromagnetic energy into excess of biochemical energy released by the isolated organelles.


Asunto(s)
Mitocondrias Hepáticas , Animales , Bovinos , Mitocondrias Hepáticas/metabolismo , Mitocondrias Hepáticas/efectos de la radiación , Terapia por Luz de Baja Intensidad/métodos , Metabolismo Energético , Termodinámica , Campos Electromagnéticos , Mitocondrias/metabolismo , Mitocondrias/efectos de la radiación
6.
Org Biomol Chem ; 22(19): 3966-3978, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38690804

RESUMEN

Amino acid and peptide radicals are of broad interest due to their roles in biochemical oxidative damage, pathogenesis and protein radical catalysis, among others. Using density functional theory (DFT) calculations at the ωB97X-D/def2-QZVPPD//ωB97X-D/def2-TZVPP level of theory, we systematically investigated the hydrogen bonding between water and fourteen α-amino acids (Ala, Asn, Cys, Gln, Gly, His, Met, Phe, Pro, Sel, Ser, Thr, Trp, and Tyr) in both neutral and radical cation forms. For all amino acids surveyed, stronger hydrogen-bonding interactions with water were observed upon single-electron oxidation, with the greatest increases in hydrogen-bonding strength occurring in Gly, Ala and His. We demonstrate that the side chain has a significant impact on the most favorable hydrogen-bonding modes experienced by amino acid radical cations. Our computations also explored the fragmentation of amino acid radical cations through the loss of a COOH radical facilitated by hydrogen bonding. The most favorable pathways provided stabilization of the resulting cationic fragments through hydrogen bonding, resulting in more favorable thermodynamics for the fragmentation process. These results indicate that non-covalent interactions with the environment have a profound impact on the structure and chemical fate of oxidized amino acids.


Asunto(s)
Aminoácidos , Cationes , Teoría Funcional de la Densidad , Enlace de Hidrógeno , Aminoácidos/química , Cationes/química , Radicales Libres/química , Termodinámica , Agua/química , Modelos Moleculares
7.
Phys Chem Chem Phys ; 26(19): 14160-14170, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38712976

RESUMEN

Protonated ions of fucose-containing oligosaccharides are prone to undergo internal glycan rearrangement which results in chimeric fragments that obfuscate mass-spectrometric analysis. Lack of accessible tools that would facilitate systematic analysis of glycans in the gas phase limits our understanding of this phenomenon. In this work, we use density functional theory modeling to interpret cryogenic IR spectra of Lewis a and blood group type H1 trisaccharides and to establish whether these trisaccharides undergo the rearrangement during gas-phase analysis. Structurally unconstrained search reveals that none of the parent ions constitute a thermodynamic global minimum. In contrast, predicted collision cross sections and anharmonic IR spectra provide a good match to available experimental data which allowed us to conclude that fucose migration does not occur in these antigens. By comparing the predicted structures with those obtained for Lewis x and blood group type H2 epitopes, we demonstrate that the availability of the mobile proton and a large difference in the relative stability of the parent ions and rearrangement products constitute the prerequisites for the rearrangement reaction.


Asunto(s)
Antígenos del Grupo Sanguíneo de Lewis , Antígenos del Grupo Sanguíneo de Lewis/química , Epítopos/química , Termodinámica , Polisacáridos/química , Teoría Funcional de la Densidad , Antígenos de Grupos Sanguíneos/química , Espectrofotometría Infrarroja , Oligosacáridos/química , Trisacáridos/química
8.
Nat Commun ; 15(1): 4026, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38740822

RESUMEN

Unstable proteins are prone to form non-native interactions with other proteins and thereby may become toxic. To mitigate this, destabilized proteins are targeted by the protein quality control network. Here we present systematic studies of the cytosolic aspartoacylase, ASPA, where variants are linked to Canavan disease, a lethal neurological disorder. We determine the abundance of 6152 of the 6260 ( ~ 98%) possible single amino acid substitutions and nonsense ASPA variants in human cells. Most low abundance variants are degraded through the ubiquitin-proteasome pathway and become toxic upon prolonged expression. The data correlates with predicted changes in thermodynamic stability, evolutionary conservation, and separate disease-linked variants from benign variants. Mapping of degradation signals (degrons) shows that these are often buried and the C-terminal region functions as a degron. The data can be used to interpret Canavan disease variants and provide insight into the relationship between protein stability, degradation and cell fitness.


Asunto(s)
Amidohidrolasas , Enfermedad de Canavan , Proteolisis , Humanos , Amidohidrolasas/genética , Amidohidrolasas/metabolismo , Enfermedad de Canavan/genética , Enfermedad de Canavan/metabolismo , Células HEK293 , Sustitución de Aminoácidos , Mutación , Complejo de la Endopetidasa Proteasomal/metabolismo , Complejo de la Endopetidasa Proteasomal/genética , Estabilidad Proteica , Ubiquitina/metabolismo , Termodinámica
9.
Nat Commun ; 15(1): 3897, 2024 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-38719841

RESUMEN

Understanding enzyme catalysis as connected to protein motions is a major challenge. Here, based on temperature kinetic studies combined with isotope effect measurements, we obtain energetic description of C-H activation in NAD-dependent UDP-glucuronic acid C4 epimerase. Approach from the ensemble-averaged ground state (GS) to the transition state-like reactive conformation (TSRC) involves, alongside uptake of heat ( Δ H ‡ = 54 kJ mol-1), significant loss in entropy ( - T Δ S ‡ = 20 kJ mol-1; 298 K) and negative activation heat capacity ( Δ C p ‡ = -0.64 kJ mol-1 K-1). Thermodynamic changes suggest the requirement for restricting configurational freedom at the GS to populate the TSRC. Enzyme variants affecting the electrostatic GS preorganization reveal active-site interactions important for precise TSRC sampling and H-transfer. Collectively, our study captures thermodynamic effects associated with TSRC sampling and establishes rigid positioning for C-H activation in an enzyme active site that requires conformational flexibility in fulfillment of its natural epimerase function.


Asunto(s)
Dominio Catalítico , Termodinámica , Cinética , Conformación Proteica , Carbohidrato Epimerasas/química , Carbohidrato Epimerasas/metabolismo , Carbohidrato Epimerasas/genética , Biocatálisis , Catálisis , Modelos Moleculares
10.
J Phys Chem B ; 128(18): 4456-4463, 2024 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-38691101

RESUMEN

Ionic liquids (ILs) have shown promising potential in membrane protein extraction; however, the underlying mechanism remains unclear. Herein, we employed GPU-accelerated molecular dynamics (MD) simulations to investigate the dynamic insertion process of ILs into cell membranes containing membrane proteins. Our findings reveal that ILs spontaneously insert into the membrane, and the presence of membrane proteins significantly decelerates the rate of IL insertion into the membrane. Specifically, the relationship between the insertion rate and inserting free energy exhibits non-monotonic changes, which can be attributed to interfacial effects. The protein-water interface acts as trap for free ions and ionic clusters, while free ions preferentially insert into the membrane from the protein-lipid interface, which limits the insertion rate due to its narrowness. Thus, the insertion rate is governed by a combination of the free energy and interfacial effects. These findings provide valuable insights into the interfacial effects of protein-lipid bilayers and have implications for various biochemical-related applications.


Asunto(s)
Membrana Celular , Imidazoles , Líquidos Iónicos , Membrana Dobles de Lípidos , Simulación de Dinámica Molecular , Líquidos Iónicos/química , Imidazoles/química , Membrana Celular/química , Membrana Celular/metabolismo , Membrana Dobles de Lípidos/química , Membrana Dobles de Lípidos/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Termodinámica , Agua/química
11.
Prog Nucl Magn Reson Spectrosc ; 140-141: 42-48, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38705635

RESUMEN

Most proteins perform their functions in crowded and complex cellular environments where weak interactions are ubiquitous between biomolecules. These complex environments can modulate the protein folding energy landscape and hence affect protein stability. NMR is a nondestructive and effective method to quantify the kinetics and equilibrium thermodynamic stability of proteins at an atomic level within crowded environments and living cells. Here, we review NMR methods that can be used to measure protein stability, as well as findings of studies on protein stability in crowded environments mimicked by polymer and protein crowders and in living cells. The important effects of chemical interactions on protein stability are highlighted and compared to spatial excluded volume effects.


Asunto(s)
Resonancia Magnética Nuclear Biomolecular , Estabilidad Proteica , Proteínas , Proteínas/química , Resonancia Magnética Nuclear Biomolecular/métodos , Termodinámica , Humanos , Pliegue de Proteína , Cinética , Espectroscopía de Resonancia Magnética/métodos
12.
AAPS PharmSciTech ; 25(5): 93, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38693316

RESUMEN

Tolterodine tartrate (TOTA) is associated with adverse effect, high hepatic access, varied bioavailability, slight aqueous solubility, and short half-life after oral delivery. Hansen solubility parameters (HSP, HSPiP program), experimental solubility (T = 298.2 to 318.2 K and p = 0.1 MPa), computational (van't Hoff and Apelblat models), and thermodynamic models were used to the select solvent(s). HSPiP predicted PEG400 as the most suitable co-solvent based on HSP values (δd = 17.88, δp = 4.0, and δh = 8.8 of PEG400) and comparable to the drug (δd = 17.6, δp = 2.4, and δh = 4.6 of TOTA). The experimental mole fraction solubility of TOTA was maximum (xe = 0.0852) in PEG400 confirming the best fit of the prediction. The observed highest solubility was attributed to the δp and δh interacting forces. The activity coefficient (ϒi) was found to be increased with temperature. The higher values of r2 (linear regression coefficient) and low RMSD (root mean square deviation) indicated a good correlation between the generated "xe" data for crystalline TOTA and the explored models (modified Apelblat and van't Hoff models). TOTA solubility in "PEG400 + water mixture" was endothermic and entropy-driven. IR (immediate release product) formulation can be tailored using 60% PEG400 in buffer solution for 2 mg of TOTA in 0.25 mL (dosing volume). The isotonic binary solution was associated with a pH of 7.2 suitable for sub-Q delivery. The approach would be a promising alternative with ease of delivery to children and aged patients.


Asunto(s)
Solubilidad , Solventes , Termodinámica , Tartrato de Tolterodina , Humanos , Tartrato de Tolterodina/administración & dosificación , Tartrato de Tolterodina/química , Tartrato de Tolterodina/farmacocinética , Solventes/química , Polietilenglicoles/química , Disponibilidad Biológica , Química Farmacéutica/métodos , Inyecciones Subcutáneas , Sistemas de Liberación de Medicamentos/métodos
13.
Sci Rep ; 14(1): 9972, 2024 04 30.
Artículo en Inglés | MEDLINE | ID: mdl-38693342

RESUMEN

This study presents a novel biosorbent developed by immobilizing dead Sp2b bacterial biomass into calcium alginate (CASp2b) to efficiently remove arsenic (AsIII) from contaminated water. The bacterium Sp2b was isolated from arsenic-contaminated industrial soil of Punjab, a state in India. The strain was designated Acinetobacter sp. strain Sp2b as per the 16S rDNA sequencing, GenBank accession number -OP010048.The CASp2b was used for the biosorption studies after an initial screening for the biosorption capacity of Sp2b biomass with immobilized biomass in both live and dead states. The optimum biosorption conditions were examined in batch experimentations with contact time, pH, biomass, temperature, and AsIII concentration variables. The maximum biosorption capacity (qmax = 20.1 ± 0.76 mg/g of CA Sp2b) was obtained at pH9, 35 ̊ C, 20 min contact time, and 120 rpm agitation speed. The isotherm, kinetic and thermodynamic modeling of the experimental data favored Freundlich isotherm (R2 = 0.941) and pseudo-2nd-order kinetics (R2 = 0.968) with endothermic nature (ΔH° = 27.42) and high randomness (ΔS° = 58.1).The scanning electron microscopy with energy dispersive X-ray (SEM-EDX) analysis indicated the As surface binding. The reusability study revealed the reasonable usage of beads up to 5 cycles. In conclusion, CASp2b is a promising, efficient, eco-friendly biosorbent for AsIII removal from contaminated water.


Asunto(s)
Acinetobacter , Alginatos , Arsénico , Biodegradación Ambiental , Biomasa , Contaminantes Químicos del Agua , Alginatos/química , Alginatos/metabolismo , Acinetobacter/metabolismo , Acinetobacter/genética , Arsénico/metabolismo , Contaminantes Químicos del Agua/metabolismo , Adsorción , Cinética , Concentración de Iones de Hidrógeno , Purificación del Agua/métodos , Temperatura , Termodinámica
14.
Yakugaku Zasshi ; 144(5): 545-551, 2024.
Artículo en Japonés | MEDLINE | ID: mdl-38692931

RESUMEN

The membrane permeability, and its evaluation, is crucial factor in the process of uptake of compounds from outside to inside the cell and in the inhibition of the activity of disease-causing target proteins. Although molecular dynamics (MD) simulations have been shown to be able to reproduce the conformational changes of compounds occurring during membrane permeation, it is still challenging to extract the membrane permeability at an affordable computational workload solely by conventional MD. Indeed, the time scale accessible by MD is far below the one characterizing the actual permeation process. Phenomena occurring in living organisms escaping the reach of standard MD are generally referred to as biological rare events, and the membrane permeation process is one of them. To overcome this time-scale problem, several enhanced sampling methods have been proposed over the years to improve conformational sampling. In this review, a hybrid sampling method that combines the parallel cascade selection MD (PaCS-MD) and the outlier flooding method (OFLOOD), introduced and developed by our group, is proposed as a tool to study the membrane permeation from structural sampling (rare-event sampling). The obtained trajectories are used to estimate the free energy profiles for the membrane permeation and to compute the membrane permeation coefficients. Moreover, we present an example of application of the free energy reaction network method as a versatile way for incorporating explicitly into reaction coordinates the degrees of freedom related to internal motion.


Asunto(s)
Permeabilidad de la Membrana Celular , Simulación de Dinámica Molecular , Termodinámica , Conformación Molecular
15.
Chirality ; 36(5): e23672, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38693625

RESUMEN

Hydroxychloroquine (HCQ), 2-([4-([7-Chloro-4-quinolyl]amino)pentyl]ethylamino)ethanol, exhibited significant biological activity, while its side effects cannot be overlooked. The RP-HPLC enantio-separation was investigated for cost-effective and convenient optical purity analysis of HCQ. The thermodynamic resolution of Rac-HCQ, driven by enthalpy and entropy, was achieved on the C18 column using Carboxymethyl-ß-cyclodextrin (CM-ß-CD) as the chiral mobile phase agent (CMPA). The effects of CCM-ß-CD, pH, and triethylamine (TEA) V% on the enantio-separation process were explored. Under the optimum conditions at 24°C, the retention times for the two enantiomers were t R 1 = 29.39 min $$ {t}_{R1}=29.39\ \min $$ and t R 2 = 32.42 min $$ {t}_{R2}=32.42\ \min $$ , resulting in R s = 1.87 $$ {R}_s=1.87 $$ . The resolution via diastereomeric salt formation of Rac-HCQ was developed to obtain the active pharmaceutical ingredient of single enantiomer S-HCQ. Di-p-Anisoyl-L-Tartaric Acid (L-DATA) was proved effective as the resolution agent for Rac-HCQ. Surprisingly, it was found that refluxing time was a key fact affecting the resolution efficiency, which meant the kinetic dominate during the process of the resolution. Four factors-solvent volume, refluxing time, filtration temperature, and molar ratio-were optimized using the single-factor method and the response surface method. Two cubic models were established, and the reliability was subsequently verified. Under the optimal conditions, the less soluble salt of 2L-DATA:S-HCQ was obtained with a yield of 96.9% and optical purity of 63.0%. The optical purity of this less soluble salt increases to 99.0% with a yield of 74.2% after three rounds recrystallization.


Asunto(s)
Hidroxicloroquina , Hidroxicloroquina/química , Estereoisomerismo , Cromatografía Líquida de Alta Presión/métodos , Concentración de Iones de Hidrógeno , beta-Ciclodextrinas/química , Cromatografía de Fase Inversa/métodos , Etilaminas/química , Termodinámica , Sales (Química)/química
16.
Proc Natl Acad Sci U S A ; 121(21): e2322428121, 2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38739795

RESUMEN

Protein evolution is guided by structural, functional, and dynamical constraints ensuring organismal viability. Pseudogenes are genomic sequences identified in many eukaryotes that lack translational activity due to sequence degradation and thus over time have undergone "devolution." Previously pseudogenized genes sometimes regain their protein-coding function, suggesting they may still encode robust folding energy landscapes despite multiple mutations. We study both the physical folding landscapes of protein sequences corresponding to human pseudogenes using the Associative Memory, Water Mediated, Structure and Energy Model, and the evolutionary energy landscapes obtained using direct coupling analysis (DCA) on their parent protein families. We found that generally mutations that have occurred in pseudogene sequences have disrupted their native global network of stabilizing residue interactions, making it harder for them to fold if they were translated. In some cases, however, energetic frustration has apparently decreased when the functional constraints were removed. We analyzed this unexpected situation for Cyclophilin A, Profilin-1, and Small Ubiquitin-like Modifier 2 Protein. Our analysis reveals that when such mutations in the pseudogene ultimately stabilize folding, at the same time, they likely alter the pseudogenes' former biological activity, as estimated by DCA. We localize most of these stabilizing mutations generally to normally frustrated regions required for binding to other partners.


Asunto(s)
Evolución Molecular , Pliegue de Proteína , Seudogenes , Seudogenes/genética , Humanos , Mutación , Secuencia de Aminoácidos , Proteínas/genética , Proteínas/química , Proteínas/metabolismo , Termodinámica
17.
Langmuir ; 40(19): 10157-10170, 2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38700902

RESUMEN

I-Motif (iM) DNA structures represent among the most significant noncanonical nucleic acid configurations. iM-forming DNA sequences are found in an array of vital genomic locations and are particularly frequent in the promoter islands of various oncogenes. Thus, iM DNA is a crucial candidate for anticancer medicines; therefore, binding interactions between iM DNA and small molecular ligands, such as flavonoids, are critically important. Extensive sets of spectroscopic strategies and thermodynamic analysis were utilized in the present investigation to find out the favorable interaction of quercetin (Que), a dietary flavonoid that has various health-promoting characteristics, including anticancer properties, with noncanonical iM DNA structure. Spectroscopic studies and thermal analysis revealed that Que interacts preferentially with HRAS1 iM DNA compared with VEGF, BCL2 iM, and duplex DNA. Que, therefore, emerged as a suitable natural-product-oriented antagonist for targeting HRAS1 iM DNA. The innovative spectroscopic as well as mechanical features of Que and its specific affinity for HRAS1 iM may be useful for therapeutic applications and provide crucial insights for the design of compounds with remarkable medicinal properties.


Asunto(s)
ADN , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas p21(ras) , Quercetina , Quercetina/química , Quercetina/farmacología , Quercetina/metabolismo , ADN/química , ADN/metabolismo , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Proto-Oncogénicas p21(ras)/química , Proteínas Proto-Oncogénicas p21(ras)/antagonistas & inhibidores , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Termodinámica , Humanos , Motivos de Nucleótidos , Sitios de Unión
18.
Molecules ; 29(9)2024 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-38731486

RESUMEN

Carbonic anhydrases are mononuclear metalloenzymes catalyzing the reversible hydration of carbon dioxide in organisms belonging to all three domains of life. Although the mechanism of the catalytic reaction is similar, different families of carbonic anhydrases do not have a common ancestor nor do they exhibit significant resemblance in the amino acid sequence or the structure and composition of the metal-binding sites. Little is known about the physical principles determining the metal affinity and selectivity of the catalytic centers, and how well the native metal is protected from being dislodged by other metal species from the local environment. Here, we endeavor to shed light on these issues by studying (via a combination of density functional theory calculations and polarizable continuum model computations) the thermodynamic outcome of the competition between the native metal cation and its noncognate competitor in various metal-binding sites. Typical representatives of the competing cations from the cellular environments of the respective classes of carbonic anhydrases are considered. The calculations reveal how the Gibbs energy of the metal competition changes when varying the metal type, structure, composition, and solvent exposure of the active center. Physical principles governing metal competition in different carbonic anhydrase metal-binding sites are delineated.


Asunto(s)
Anhidrasas Carbónicas , Dominio Catalítico , Metales , Termodinámica , Anhidrasas Carbónicas/química , Anhidrasas Carbónicas/metabolismo , Metales/química , Sitios de Unión , Modelos Moleculares
19.
Molecules ; 29(9)2024 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-38731555

RESUMEN

Anthocyanins are colored water-soluble plant pigments. Upon consumption, anthocyanins are quickly absorbed and can penetrate the blood-brain barrier (BBB). Research based on population studies suggests that including anthocyanin-rich sources in the diet lowers the risk of neurodegenerative diseases. The copigmentation caused by copigments is considered an effective way to stabilize anthocyanins against adverse environmental conditions. This is attributed to the covalent and noncovalent interactions between colored forms of anthocyanins (flavylium ions and quinoidal bases) and colorless or pale-yellow organic molecules (copigments). The present work carried out a theoretical study of the copigmentation process between cyanidin and resveratrol (CINRES). We used three levels of density functional theory: M06-2x/6-31g+(d,p) (d3bj); ωB97X-D/6-31+(d,p); APFD/6-31+(d,p), implemented in the Gaussian16W package. In a vacuum, the CINRES was found at a copigmentation distance of 3.54 Å between cyanidin and resveratrol. In water, a binding free energy ∆G was calculated, rendering -3.31, -1.68, and -6.91 kcal/mol, at M06-2x/6-31g+(d,p) (d3bj), ωB97X-D/6-31+(d,p), and APFD/6-31+(d,p) levels of theory, respectively. A time-dependent density functional theory (TD-DFT) was used to calculate the UV spectra of the complexes and then compared to its parent molecules, resulting in a lower energy gap at forming complexes. Excited states' properties were analyzed with the ωB97X-D functional. Finally, Shannon aromaticity indices were calculated and isosurfaces of non-covalent interactions were evaluated.


Asunto(s)
Antocianinas , Teoría Funcional de la Densidad , Resveratrol , Antocianinas/química , Resveratrol/química , Termodinámica , Modelos Moleculares , Agua/química
20.
Molecules ; 29(9)2024 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-38731553

RESUMEN

One-step carbonization was explored to prepare biochar using the residue of a traditional Chinese herbal medicine, Atropa belladonna L. (ABL), as the raw material. The resulting biochar, known as ABLB4, was evaluated for its potential as a sustainable material for norfloxacin (NOR) adsorption in water. Subsequently, a comprehensive analysis of adsorption isotherms, kinetics, and thermodynamics was conducted through batch adsorption experiments. The maximum calculated NOR adsorption capacity was 252.0 mg/g at 298 K, and the spontaneous and exothermic adsorption of NOR on ABLB4 could be better suited to a pseudo-first-order kinetic model and Langmuir model. The adsorption process observed is influenced by pore diffusion, π-π interaction, electrostatic interaction, and hydrogen bonding between ABLB4 and NOR molecules. Moreover, the utilization of response surface modeling (RSM) facilitated the optimization of the removal efficiency of NOR, yielding a maximum removal rate of 97.4% at a temperature of 304.8 K, an initial concentration of 67.1 mg/L, and a pH of 7.4. Furthermore, the biochar demonstrated favorable economic advantages, with a payback of 852.5 USD/t. More importantly, even after undergoing five cycles, ABLB4 exhibited a consistently high NOR removal rate, indicating its significant potential for application in NOR adsorption.


Asunto(s)
Carbón Orgánico , Medicamentos Herbarios Chinos , Norfloxacino , Contaminantes Químicos del Agua , Norfloxacino/química , Carbón Orgánico/química , Adsorción , Medicamentos Herbarios Chinos/química , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Cinética , Termodinámica , Purificación del Agua/métodos , Concentración de Iones de Hidrógeno
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