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1.
Environ Microbiol ; 26(5): e16627, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38733112

RESUMEN

Soil structure and aggregation are crucial for soil functionality, particularly under drought conditions. Saprobic soil fungi, known for their resilience in low moisture conditions, are recognized for their influence on soil aggregate dynamics. In this study, we explored the potential of fungal amendments to enhance soil aggregation and hydrological properties across different moisture regimes. We used a selection of 29 fungal isolates, recovered from soils treated under drought conditions and varying in colony density and growth rate, for single-strain inoculation into sterilized soil microcosms under either low or high moisture (≤-0.96 and -0.03 MPa, respectively). After 8 weeks, we assessed soil aggregate formation and stability, along with soil properties such as soil water content, water hydrophobicity, sorptivity, total fungal biomass and water potential. Our findings indicate that fungal inoculation altered soil hydrological properties and improved soil aggregation, with effects varying based on the fungal strains and soil moisture levels. We found a positive correlation between fungal biomass and enhanced soil aggregate formation and stabilization, achieved by connecting soil particles via hyphae and modifying soil aggregate sorptivity. The improvement in soil water potential was observed only when the initial moisture level was not critical for fungal activity. Overall, our results highlight the potential of using fungal inoculation to improve the structure of agricultural soil under drought conditions, thereby introducing new possibilities for soil management in the context of climate change.


Asunto(s)
Hongos , Microbiología del Suelo , Suelo , Agua , Suelo/química , Hongos/crecimiento & desarrollo , Agua/química , Biomasa , Sequías
2.
Food Res Int ; 186: 114400, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38729703

RESUMEN

Since hydrothermal treatments can enhance resistant starch (RS) content in rice and provide health benefits when consumed, a less laborious and non-destructive method to determine RS content is needed. Terahertz (THz) spectroscopy is hypothesized as a suitable method to quantify RS content in rice after hydrothermal treatment with its sensitivity for the intermolecular forces increase in the formation of RS. In this study, we first used the traditional in vitro hydrolysis method to determine the content of RS in rice. Then, the potential of starch absorbance peaks to quantify RS content after three commonly used hydrothermal methods, soaking, mild heat-moisture treatment, and parboiling, was investigated. The second derivative intensities of the peak at 9.0, 10.5, 12.1, and 13.1 THz were confirmed as being correlated with RS content and showed the high accuracy to predict RS content in samples (R2 > 0.96). Our results indicate the RS content of hydrothermally treated rice can be accurately quantified using these peaks.


Asunto(s)
Calor , Oryza , Almidón , Espectroscopía de Terahertz , Oryza/química , Almidón/análisis , Espectroscopía de Terahertz/métodos , Hidrólisis , Almidón Resistente/análisis , Manipulación de Alimentos/métodos , Agua/química
3.
Food Res Int ; 186: 114320, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38729710

RESUMEN

High-moisture extrusion (HME) is widely used to produce meat analogues. During HME the plant-based materials experience thermal and mechanical stresses. It is complicated to separate their effects on the final products because these effects are interrelated. In this study we hypothesize that the intensity of the thermal treatment can explain a large part of the physicochemical changes that occur during extrusion. For this reason, near-infrared (NIR) spectroscopy was used as a novel method to quantify the thermal process intensity during HME. High-temperature shear cell (HTSC) processing was used to create a partial least squares (PLS) regression curve for processing temperature under controlled processing conditions (root mean standard error of cross-validation (RMSECV) = 4.00 °C, coefficient of determination of cross-validation (R2CV) = 0.97). This PLS regression model was then applied to HME extrudates produced at different screw speeds (200-1200 rpm) and barrel temperatures (100-160 °C) with two different screw profiles to calculate the equivalent shear cell temperature as a measure for thermal process intensity. This equivalent shear cell temperature reflects the effects of changes in local temperature conditions, residence time and thermal stresses. Furthermore, it can be related to the degree of texturization of the extrudates. This information can be used to gain new insights into the effect of various process parameters during HME on the thermal process intensity and extrudate quality.


Asunto(s)
Manipulación de Alimentos , Calor , Proteínas de Soja , Espectroscopía Infrarroja Corta , Espectroscopía Infrarroja Corta/métodos , Manipulación de Alimentos/métodos , Proteínas de Soja/química , Proteínas de Soja/análisis , Análisis de los Mínimos Cuadrados , Agua/química
4.
Food Res Int ; 186: 114374, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38729731

RESUMEN

As a crucial component of the fungal cell membranes, ergosterol has been demonstrated to possess surface activity attributed to its hydrophobic region and polar group. However, further investigation is required to explore its emulsification behavior upon migration to the oil-water interface. Therefore, this study was conducted to analyze the interface properties of ergosterol as a stabilizer for water in oil (W/O) emulsion. Moreover, the emulsion prepared under the optimal conditions was utilized to load the water-soluble bioactive substance with the chlorogenic acid as the model molecules. Our results showed that the contact angle of ergosterol was 117.017°, and its dynamic interfacial tension was obviously lower than that of a pure water-oil system. When the ratio of water to oil was 4: 6, and the content of ergosterol was 3.5 % (ergosterol/oil phase, w/w), the W/O emulsion had smaller particle size (438 nm), higher apparent viscosity, and better stability. Meanwhile, the stability of loaded chlorogenic acid was improved under unfavorable conditions (pH 1.2, 90 °C, ultraviolet irradiation, and oxidation), which were 73.87 %, 59.53 %, 62.53 %, and 69.73 %, respectively. Additionally, the bioaccessibility of chlorogenic acid (38.75 %) and ergosterol (33.69 %), and the scavenging rates of the emulsion on DPPH radicals (81.00 %) and hydroxyl radicals (82.30 %) were also enhanced. Therefore, a novel W/O Pickering emulsion was prepared in this work using ergosterol as an emulsifier solely, which has great potential for application in oil-based food and nutraceutical formulations.


Asunto(s)
Ácido Clorogénico , Emulsionantes , Emulsiones , Ergosterol , Tamaño de la Partícula , Agua , Ergosterol/química , Emulsiones/química , Emulsionantes/química , Agua/química , Ácido Clorogénico/química , Viscosidad , Antioxidantes/química , Aceites/química , Concentración de Iones de Hidrógeno
5.
Water Sci Technol ; 89(9): 2512-2522, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38747964

RESUMEN

This manuscript presents a novel approach for developing an environmentally friendly and effective oil-water separation membrane. Achieving a superhydrophobic (SH) coating on textile fabric (TF) involved a two-step process. Initially, the surface roughness was enhanced by applying bio-zinc oxide (ZnO) nanoparticles obtained from Thymbra spicata L. Subsequently, the roughened surface was modified with stearic acid, a material known for its low surface energy. The bio-ZnO nanoparticles exhibit a circular morphology with an average size of 21 nm. The coating demonstrated remarkable mechanical stability, maintaining SH properties even after an abrasion length of 300 mm. Chemical stability studies revealed that the prepared membrane retained SH properties within a pH range of 5-11, which ensures robust performance. Absorption capacity measurements showcased different capacities for n-hexane (Hex), corn oil (C.O), and silicone oil (S.O), with consistent performance over 10 absorption-desorption cycles. High oil-water separation efficiencies were achieved for hexane, C.O, and S.O, emphasizing the coating's versatility. Flux rate measurements demonstrated that oil passed through the membrane efficiently, with the highest flux observed for Hex. The prepared SH membrane has superior mechanical and chemical stability and high separation efficiencies, which positions it as a promising candidate for diverse industrial applications.


Asunto(s)
Interacciones Hidrofóbicas e Hidrofílicas , Membranas Artificiales , Óxido de Zinc , Óxido de Zinc/química , Agua/química , Aceites/química
6.
Sci Rep ; 14(1): 11047, 2024 05 14.
Artículo en Inglés | MEDLINE | ID: mdl-38744989

RESUMEN

Callicarpa kwangtungensis Chun (CK) is a common remedy exhibits anti-inflammatory properties and has been used in Chinese herbal formulations, such as KangGongYan tablets. It is the main component of KangGongYan tablets, which has been used to treat chronic cervicitis caused by damp heat, red and white bands, cervical erosion, and bleeding. However, the anti-inflammatory effects of CK water extract remains unknown. This study assessed the anti-inflammatory effects of CK in vivo and in vitro, characterized its main components in the serum of rats and verified the anti-inflammatory effects of serum containing CK. Nitric oxide (NO), tumour necrosis factor α (TNF-α) and interleukin-6 (IL-6) release by RAW264.7 cells was examined by ELISA and Griess reagents. Inflammation-related protein expression in LPS-stimulated RAW264.7 cells was measured by western blotting. Furthermore, rat model of foot swelling induced by λ-carrageenan and a collagen-induced arthritis (CIA) rat model were used to explore the anti-inflammatory effects of CK. The components of CK were characterized by LC-MS, and the effects of CK-containing serum on proinflammatory factors levels and the expression of inflammation-related proteins were examined by ELISA, Griess reagents and Western blotting. CK suppressed IL-6, TNF-α, and NO production, and iNOS protein expression in LPS-stimulated RAW264.7 cells. Mechanistic studies showed that CK inhibited the phosphorylation of ERK, P38 and JNK in the MAPK signaling pathway, promoted the expression of IκBα in the NF-κB signaling pathway, and subsequently inhibited the expression of iNOS, thereby exerting anti-inflammatory effects. Moreover, CK reduced the swelling rates with λ-carrageenan induced foot swelling, and reduced the arthritis score and incidence in the collagen-induced arthritis (CIA) rat model. A total of 68 compounds in CK water extract and 31 components in rat serum after intragastric administration of CK were characterized. Serum pharmacological analysis showed that CK-containing serum suppressed iNOS protein expression and NO, TNF-α, and IL-6 release. CK may be an anti-inflammatory agent with therapeutic potential for acute and chronic inflammatory diseases, especially inflammatory diseases associated with MAPK activation.


Asunto(s)
Antiinflamatorios , Artritis Experimental , Óxido Nítrico , Extractos Vegetales , Animales , Ratones , Antiinflamatorios/farmacología , Antiinflamatorios/química , Ratas , Células RAW 264.7 , Extractos Vegetales/farmacología , Extractos Vegetales/química , Óxido Nítrico/metabolismo , Artritis Experimental/tratamiento farmacológico , Agua/química , Carragenina , Modelos Animales de Enfermedad , Factor de Necrosis Tumoral alfa/metabolismo , Factor de Necrosis Tumoral alfa/sangre , Masculino , Interleucina-6/metabolismo , Interleucina-6/sangre , Edema/tratamiento farmacológico , Inflamación/tratamiento farmacológico
7.
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
8.
J Am Chem Soc ; 146(19): 13588-13597, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38695646

RESUMEN

Membrane channel proteins (MCPs) play key roles in matter transport through cell membranes and act as major targets for vaccines and drugs. For emerging ionic liquid (IL) drugs, a rational understanding of how ILs affect the structure and transport function of MCP is crucial to their design. In this work, GPU-accelerated microsecond-long molecular dynamics simulations were employed to investigate the modulating mechanism of ILs on MCP. Interestingly, ILs prefer to insert into the lipid bilayer and channel of aquaporin-2 (AQP2) but adsorb on the entrance of voltage-gated sodium channels (Nav). Molecular trajectory and free energy analysis reflect that ILs have a minimal impact on the structure of MCPs but significantly influence MCP functions. It demonstrates that ILs can decrease the overall energy barrier for water through AQP2 by 1.88 kcal/mol, whereas that for Na+ through Nav is increased by 1.70 kcal/mol. Consequently, the permeation rates of water and Na+ can be enhanced and reduced by at least 1 order of magnitude, respectively. Furthermore, an abnormal IL gating mechanism was proposed by combining the hydrophobic nature of MCP and confined water/ion coordination effects. More importantly, we performed experiments to confirm the influence of ILs on AQP2 in human cells and found that treatment with ILs significantly accelerated the changes in cell volume in response to altered external osmotic pressure. Overall, these quantitative results will not only deepen the understanding of IL-cell interactions but may also shed light on the rational design of drugs and disease diagnosis.


Asunto(s)
Líquidos Iónicos , Simulación de Dinámica Molecular , Líquidos Iónicos/química , Líquidos Iónicos/farmacología , Humanos , Acuaporina 2/metabolismo , Acuaporina 2/química , Agua/química , Membrana Dobles de Lípidos/química , Membrana Dobles de Lípidos/metabolismo , Sodio/química , Sodio/metabolismo
9.
Biomed Phys Eng Express ; 10(4)2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38697029

RESUMEN

Plasma medicine is gaining attraction in the medical field, particularly the use of cold atmospheric plasma (CAP) in biomedicine. The chemistry of the plasma is complex, and the reactive oxygen species (ROS) within it are the basis for the biological effect of CAP on the target. Understanding how the oxidative power of ROS responds to diverse plasma parameters is vital for standardizing the effective application of CAP. The proven applicability of machine learning (ML) in the field of medicine is encouraging, as it can also be applied in the field of plasma medicine to correlate the oxidative strength of plasma-treated water (PTW) according to different parameters. In this study, plasma-treated water was mixed with potassium iodide-starch reagent for color formation that could be linked to the oxidative capacity of PTW. Corresponding images were captured resulting from the exposure of the color-forming agent to water treated with plasma for different time points. Several ML models were trained to distinguish the color changes sourced by the oxidative strength of ROS. The AdaBoost Classifier (ABC) algorithm demonstrated better performance among the classification models used by extracting color-based features from the images. Our results, with a test accuracy of 63.5%, might carry a potential for future standardization in the field of plasma medicine with an automated system that can be created to interpret the oxidative properties of ROS in different plasma treatment parameters via ML.


Asunto(s)
Algoritmos , Aprendizaje Automático , Oxidación-Reducción , Gases em Plasma , Especies Reactivas de Oxígeno , Agua , Gases em Plasma/química , Agua/química , Color
10.
J Am Chem Soc ; 146(19): 13247-13257, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38701006

RESUMEN

Horseradish peroxidase (HRP) is an enzyme that oxidizes pollutants from wastewater. A previous report indicated that peroxidases can have an enhancement in initial enzymatic activity in an aqueous solution of 0.26 M 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIm][EtSO4]) at neutral pH. However, the atomistic details remain elusive. In the enzymatic landscape of HRP, compound II (Cpd II) plays a key role and involves a histidine (H42) residue. Cpd II exists as oxoferryl (2a) or hydroxoferryl (2b(FeIV)) forms, where 2a is the predominantly observed form in experimental studies. Intriguingly, the ferric 2b(FeIII) form seen in synthetic complexes has not been observed in HRP. Here, we have investigated the structure and dynamics of HRP in pure water and aqueous [EMIm][EtSO4] (0.26 M), as well as the reaction mechanism of 2a to 2b conversion using polarizable molecular dynamics (MD) simulations and quantum mechanics/molecular mechanics (QM/MM) calculations. When HRP is solvated in aq [EMIm][EtSO4], the catalytic water displaces, and H42 directly orients over the ferryl moiety, allowing a direct proton transfer (PT) with a significant energy barrier reduction. Conversely, in neat water, the reaction of 2a to 2b follows the previously reported mechanism. We further investigated the deprotonated form of H42. Analysis of the electric fields at the active site indicates that the aq [EMIm][EtSO4] medium facilitates the reaction by providing a more favorable environment compared with the system solvated in neat water. Overall, the atomic level supports the previous experimental observations and underscores the importance of favorable electric fields in the active site to promote catalysis.


Asunto(s)
Peroxidasa de Rábano Silvestre , Líquidos Iónicos , Simulación de Dinámica Molecular , Peroxidasa de Rábano Silvestre/química , Peroxidasa de Rábano Silvestre/metabolismo , Líquidos Iónicos/química , Imidazoles/química , Teoría Cuántica , Soluciones , Agua/química
11.
PLoS One ; 19(5): e0303096, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38713656

RESUMEN

Fast-growing poplar plantations are considered a great benefit to timber production, but water availability is a key factor limiting their growth and development, especially in arid and semi-arid ecosystems. Super-absorbent polymers facilitate more water retention in soil after rain or irrigation, and they are able to release water gradually during plant growth. This study aimed to examine the effects of reduced irrigation (60% and 30% of conventional border irrigation) co-applied with super-absorbent polymers (0, 40 kg/ha) on root exudates, enzyme activities, microbial functional diversity in rhizosphere soil, and volume increments in poplar (Populus euramericana cv. 'Neva'). The results showed that 60% border irrigation co-applied with super-absorbent polymers significantly increased the content of organic acids, amino acids and total sugars in the root exudates, and the activities of invertase, urease, dehydrogenase, and catalase in the rhizosphere soil in comparison to conventional border irrigation without super-absorbent polymers. Meanwhile, this treatment also enhanced the average well-color development, Shannon index, and McIntosh index, but decreased the Simpson index. Additionally, the average volume growth rate and relative water content of leaves reached their maximum using 60% irrigation with super-absorbent polymers, which was significantly higher than other treatments. However, using 30% irrigation with super-absorbent polymers, had a smaller effect on rhizosphere soil and volume growth than 60% irrigation with super-absorbent polymers. Therefore, using an appropriate water-saving irrigation measure (60% conventional border irrigation with super-absorbent polymers) can help to improve enzyme activities and microbial diversity in the rhizosphere soil while promoting the growth of poplar trees.


Asunto(s)
Riego Agrícola , Polímeros , Populus , Rizosfera , Microbiología del Suelo , Populus/crecimiento & desarrollo , Populus/microbiología , Riego Agrícola/métodos , Polímeros/química , Raíces de Plantas/microbiología , Raíces de Plantas/crecimiento & desarrollo , Suelo/química , Agua/química
12.
Luminescence ; 39(5): e4769, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38720528

RESUMEN

Fluorene nucleus derivatives show great potential for building outstanding fluorescence probes. In this paper, a novel fluorescent probe was developed by reacting with fluorene core with azacyclobutane, which exhibits typical solvation chromogenic effect in solvent. The fluorescence of the probe quenched in highly polar solvent. Based on this phenomenon, a novel fluorescence system for trace water was constructed. The response of this probe was fast (30 s) and sensitive for the detection of trace water in organic solvents, and the detection limit of water content in DMSO reached 0.13%. In addition, the probe can also be made as a test strip combined with homemade portable device and a smartphone for rapid detection of trace water. The luminescence mechanism of the probe is theoretically calculated based on time-contained density functional theory (TDDFT). To showcase its practicality, it has been applied for the detection of trace water in honey and alcohol by dipstick. This method provides a new idea for designing efficient fluorescent probes based on dipstick and mobile phone rapid detection.


Asunto(s)
Fluorenos , Colorantes Fluorescentes , Espectrometría de Fluorescencia , Agua , Colorantes Fluorescentes/química , Colorantes Fluorescentes/síntesis química , Fluorenos/química , Agua/química , Estructura Molecular , Límite de Detección , Teoría Funcional de la Densidad , Fluorescencia , Contaminantes Químicos del Agua/análisis
13.
Carbohydr Polym ; 337: 122164, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-38710558

RESUMEN

Water-insoluble α-glucans synthesized from sucrose by glucansucrases from Streptococcus spp. are essential in dental plaque and caries formation. Because limited information is available on the fine structure of these biopolymers, we analyzed the structures of unmodified glucans produced by five recombinant Streptococcus (S.) mutans DSM 20523 and S. salivarius DSM 20560 glucansucrases in detail. A combination of methylation analysis, endo-dextranase and endo-mutanase hydrolyses, and HPSEC-RI was used. Furthermore, crystal-like regions were analyzed by using XRD and 13C MAS NMR spectroscopy. Our results showed that the glucan structures were highly diverse: Two glucans with 1,3- and 1,6-linkages were characterized in detail besides an almost exclusively 1,3-linked and a linear 1,6-linked glucan. Furthermore, one glucan contained 1,3-, 1,4-, and 1,6-linkages and thus had an unusual, not yet described structure. It was demonstrated that the glucans had a varying structural architecture by using partial enzymatic hydrolyses. Furthermore, crystal-like regions formed by 1,3-glucopyranose units were observed for the two 1,3- and 1,6-linked glucans and the linear 1,3-linked glucan. 1,6-linked regions were mobile and not involved in the crystal-like areas. Altogether, our results broaden the knowledge of the structure of water-insoluble α-glucans from Streptococcus spp.


Asunto(s)
Glucanos , Glicosiltransferasas , Agua , Glucanos/química , Agua/química , Glicosiltransferasas/metabolismo , Glicosiltransferasas/química , Streptococcus/enzimología , Solubilidad , Streptococcus mutans/enzimología
14.
Carbohydr Polym ; 337: 122188, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-38710565

RESUMEN

Growing plants in karst areas tends to be difficult due to the easy loss of water and soil. To enhance soil agglomeration, water retention, and soil fertility, this study developed a physically and chemically crosslinked hydrogel prepared from quaternary ammonium guar gum and humic acid. The results showed that non-covalent dynamic bonds between the two components delayed humic acid release into the soil, with a release rate of only 35 % after 240 h. The presence of four hydrophilic groups (quaternary ammonium, hydroxyl, carboxyl, and carbonyl) in the hydrogel more than doubled the soil's water retention capacity. The interaction between hydrogel and soil minerals (especially carbonate and silica) promoted hydrogel-soil and soil­carbonate adhesion, and the adhesion strength between soil particles was enhanced by 650 %. Moreover, compared with direct fertilization, this degradable hydrogel not only increased the germination rate (100 %) and growth status of mung beans but also reduced the negative effects of excessive fertilization on plant roots. The study provides an eco-friendly, low-cost, and intelligent system for soil improvement in karst areas. It further proves the considerable application potential of hydrogels in agriculture.


Asunto(s)
Galactanos , Sustancias Húmicas , Hidrogeles , Mananos , Gomas de Plantas , Compuestos de Amonio Cuaternario , Suelo , Gomas de Plantas/química , Galactanos/química , Mananos/química , Hidrogeles/química , Suelo/química , Compuestos de Amonio Cuaternario/química , Fertilizantes , Preparaciones de Acción Retardada/química , Germinación/efectos de los fármacos , Agua/química
15.
PLoS One ; 19(5): e0293786, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38718010

RESUMEN

α-zeins are amphiphilic maize seed storage proteins with material properties suitable for a multitude of applications e.g., in renewable plastics, foods, therapeutics and additive manufacturing (3D-printing). To exploit their full potential, molecular-level insights are essential. The difficulties in experimental atomic-resolution characterization of α-zeins have resulted in a diversity of published molecular models. However, deep-learning α-zein models are largely unexplored. Therefore, this work studies an AlphaFold2 (AF2) model of a highly expressed α-zein using molecular dynamics (MD) simulations. The sequence of the α-zein cZ19C2 gave a loosely packed AF2 model with 7 α-helical segments connected by turns/loops. Compact tertiary structure was limited to a C-terminal bundle of three α-helices, each showing notable agreement with a published consensus sequence. Aiming to chart possible α-zein conformations in practically relevant solvents, rather than the native solid-state, the AF2 model was subjected to MD simulations in water/ethanol mixtures with varying ethanol concentrations. Despite giving structurally diverse endpoints, the simulations showed several patterns: In water and low ethanol concentrations, the model rapidly formed compact globular structures, largely preserving the C-terminal bundle. At ≥ 50 mol% ethanol, extended conformations prevailed, consistent with previous SAXS studies. Tertiary structure was partially stabilized in water and low ethanol concentrations, but was disrupted in ≥ 50 mol% ethanol. Aggregated results indicated minor increases in helicity with ethanol concentration. ß-sheet content was consistently low (∼1%) across all conditions. Beyond structural dynamics, the rapid formation of branched α-zein aggregates in aqueous environments was highlighted. Furthermore, aqueous simulations revealed favorable interactions between the protein and the crosslinking agent glycidyl methacrylate (GMA). The proximity of GMA epoxide carbons and side chain hydroxyl oxygens simultaneously suggested accessible reactive sites in compact α-zein conformations and pre-reaction geometries for methacrylation. The findings may assist in expanding the applications of these technologically significant proteins, e.g., by guiding chemical modifications.


Asunto(s)
Simulación de Dinámica Molecular , Zeína , Zeína/química , Conformación Proteica , Zea mays/química , Zea mays/metabolismo , Secuencia de Aminoácidos , Agua/química
16.
Sci Adv ; 10(19): eade9520, 2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38718112

RESUMEN

Fast collective motions are widely present in biomolecules, but their functional relevance remains unclear. Herein, we reveal that fast collective motions of backbone are critical to the water transfer of aquaporin Z (AqpZ) by using solid-state nuclear magnetic resonance (ssNMR) spectroscopy and molecular dynamics (MD) simulations. A total of 212 residue site-specific dipolar order parameters and 158 15N spin relaxation rates of the backbone are measured by combining the 13C- and 1H-detected multidimensional ssNMR spectra. Analysis of these experimental data by theoretic models suggests that the small-amplitude (~10°) collective motions of the transmembrane α helices on the nanosecond-to-microsecond timescales are dominant for the dynamics of AqpZ. The MD simulations demonstrate that these collective motions are critical to the water transfer efficiency of AqpZ by facilitating the opening of the channel and accelerating the water-residue hydrogen bonds renewing in the selectivity filter region.


Asunto(s)
Acuaporinas , Simulación de Dinámica Molecular , Agua , Agua/química , Acuaporinas/química , Acuaporinas/metabolismo , Conformación Proteica en Hélice alfa , Enlace de Hidrógeno , Espectroscopía de Resonancia Magnética , Resonancia Magnética Nuclear Biomolecular , Proteínas de Escherichia coli
17.
Clin Oral Investig ; 28(6): 305, 2024 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-38722356

RESUMEN

OBJECTIVE: To evaluate the ability of the water glass treatment to penetrate zirconia and improve the bond strength of resin cement. MATERIAL AND METHODS: Water glass was applied to zirconia specimens, which were then sintered. The specimens were divided into water-glass-treated and untreated zirconia (control) groups. The surface properties of the water-glass-treated specimens were evaluated using surface roughness and electron probe micro-analyser (EPMA) analysis. A resin cement was used to evaluate the tensile bond strength, with2 and without a silane-containing primer. After 24 h in water storage at 37 °C and thermal cycling, the bond strengths were statistically evaluated with t-test, and the fracture surfaces were observed using SEM. RESULTS: The water glass treatment slightly increased the surface roughness of the zirconia specimens, and the EPMA analysis detected the water glass penetration to be 50 µm below the zirconia surface. The application of primer improved the tensile bond strength in all groups. After 24 h, the water-glass-treated zirconia exhibited a tensile strength of 24.8 ± 5.5 MPa, which was significantly higher than that of the control zirconia (17.6 ± 3.5 MPa) (p < 0.05). After thermal cycling, the water-glass-treated zirconia showed significantly higher tensile strength than the control zirconia. The fracture surface morphology was mainly an adhesive pattern, whereas resin cement residue was occasionally detected on the water-glass-treated zirconia surfaces. CONCLUSION: The water glass treatment resulted in the formation of a stable silica phase on the zirconia surface. This process enabled silane coupling to the zirconia and improved the adhesion of the resin cement.


Asunto(s)
Recubrimiento Dental Adhesivo , Vidrio , Ensayo de Materiales , Cementos de Resina , Silanos , Propiedades de Superficie , Resistencia a la Tracción , Agua , Circonio , Circonio/química , Cementos de Resina/química , Silanos/química , Agua/química , Recubrimiento Dental Adhesivo/métodos , Vidrio/química , Microscopía Electrónica de Rastreo , Análisis del Estrés Dental
18.
J Chem Phys ; 160(18)2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38726933

RESUMEN

We investigate how electronic excitations and subsequent dissipative dynamics in the water soluble chlorophyll-binding protein (WSCP) are connected to features in two-dimensional (2D) electronic spectra, thereby comparing results from our theoretical approach with experimental data from the literature. Our calculations rely on third-order response functions, which we derived from a second-order cumulant expansion of the dissipative dynamics involving the partial ordering prescription, assuming a fast vibrational relaxation in the potential energy surfaces of excitons. Depending on whether the WSCP complex containing a tetrameric arrangement of pigments composed of two dimers with weak excitonic coupling between them binds the chlorophyll variant Chl a or Chl b, the resulting linear absorption and circular dichroism spectra and particularly the 2D spectra exhibit substantial differences in line shapes. These differences between Chl a WSCP and Chl b WSCP cannot be explained by the slightly modified excitonic couplings within the two variants. In the case of Chl a WSCP, the assumption of equivalent dimer subunits facilitates a reproduction of substantial features from the experiment by the calculations. In contrast, for Chl b WSCP, we have to assume that the sample, in addition to Chl b dimers, contains a small but distinct fraction of chemically modified Chl b pigments. The existence of such Chl b derivates has been proposed by Pieper et al. [J. Phys. Chem. B 115, 4042 (2011)] based on low-temperature absorption and hole-burning spectroscopy. Here, we provide independent evidence.


Asunto(s)
Proteínas de Unión a Clorofila , Clorofila , Agua , Clorofila/química , Agua/química , Proteínas de Unión a Clorofila/química , Análisis Espectral/métodos , Solubilidad , Dicroismo Circular
19.
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
20.
Luminescence ; 39(5): e4743, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38692854

RESUMEN

A unique luminescent lanthanide metal-organic framework (LnMOF)-based fluorescence detection platform was utilized to achieve sensitive detection of vomitoxin (VT) and oxytetracycline hydrochloride (OTC-HCL) without the use of antibodies or biomolecular modifications. The sensor had a fluorescence quenching constant of 9.74 × 106 M-1 and a low detection limit of 0.68 nM for vomitoxin. Notably, this is the first example of a Tb-MOF sensor for fluorescence detection of vomitoxin. We further investigated its response to two mycotoxins, aflatoxin B1 and ochratoxin A, and found that their Stern-Volmer fluorescence quenching constants were lower than those of VT. In addition, the fluorescence sensor realized sensitive detection of OTC-HCL with a detection limit of 0.039 µM. In conclusion, the method has great potential as a sensitive and simple technique to detect VT and OTC-HCL in water.


Asunto(s)
Estructuras Metalorgánicas , Oxitetraciclina , Terbio , Oxitetraciclina/análisis , Oxitetraciclina/química , Terbio/química , Estructuras Metalorgánicas/química , Espectrometría de Fluorescencia , Colorantes Fluorescentes/química , Límite de Detección , Agua/química , Fluorescencia , Contaminantes Químicos del Agua/análisis
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