Hen Egg White Lysozyme Research Articles

Strong and Environmental-Friendly Adhesive Glass Based on Chitin Nanoparticles

Chitin is a biopolymer that can be used as a candidate material for a strong and environmentally friendly glass adhesive. In the form of nanoparticles with needle-like morphology and attractive functional groups in the form of amide and hydroxyl, Chitin Nanoparticle (ChNP) shows a strong Van der Walls adhesive force against glass. In the study, ChNP was successfully isolated from crab shells from the sea of Lombok. The isolated ChNP has a characteristic size around 351 nm with -chitin conformation and needle-shaped morphology. Based on the results of shear strength testing, 0.42 mg of ChNP can withstand a load of 21 kg and the addition of Gum Arabic (GA) and Hen Egg White lysozyme (HEWL) in a ratio of 1: 1 to ChNP succeeded in increasing adhesion by 72%.

Determinants for Sugar-Induced modulation of thermodynamic stability of lysozyme

The current study focuses on the experimental evidence to describe the molecular mechanism by which the sugars modulate the thermodynamic stability of hen egg-white lysozyme (Lyz) at pH 2.3. Analysis of thermal and chemical denaturation curves of Lyz under variable concentrations of sugar (trehalose, sucrose, maltose, glucose, ribose, glycerol) at pH 2.3 depicted important results: (i) sugar increases the thermodynamic stability of Lyz, and it typically tracks the order as: trehalose > sucrose > maltose > glucose > ribose > glycerol, and (ii) sugar increases the thermodynamic stability of Lyz via preferential exclusion of sugar at the protein surface, but the repulsive enthalpic interactions of sugar with protein also add to the sugar-mediated increase in thermodynamic stability of the protein. Analysis of the sugar effect on denaturant concentration dependent denaturation free energy of Lyz at pH 2.3 revealed that the sugar counteracts the denaturant (urea, guanidinium chloride (GdnCl)) efficacy to decrease the thermodynamic stability of Lyz. Furthermore, the counteraction efficiency of sugar on denaturant impact to decrease thermodynamic stability of Lyz typically tracks the order as: trehalose > sucrose > maltose > glucose > ribose > glycerol.

Ankaflavin and Monascin Prevent Fibrillogenesis of Hen Egg White Lysozyme: Focus on Noncovalent and Covalent Interactions.

Misfolding and amyloid fibrillogenesis of proteins have close relationships with several neurodegenerative diseases. The present work investigates the inhibitive activities of ankaflavin (AK) and monascin (MS), two yellow pigments separated from Monascus-fermented rice, on hen egg white lysozyme (HEWL) fibrillation. The results demonstrated that AK/MS suppressed HEWL fibrillation through interfering with the nucleation period and AK was more potent. Fluorescence quenching and in silico docking studies revealed that AK/MS bond to HEWL by the formation of noncovalent forces with some critical amino acid residues that tend to form fibrils. Compared to those of AK, hydrogen bonding interactions between MS and Asn46, Trp62, and Trp63 residues in HEWL were slightly weaker. Besides, the covalent interaction between MS and HEWL with the binding site of Arg68 was found. These observations offered reasonable explanations for the difference in the mechanisms of AK and MS inhibiting HEWL fibrillogenesis. In a word, all data acquired herein indicated AK/MS as potent candidates for the improvement and treatment of neurological disorders.

Therapeutic Porphyrin “Hemin” Binds and Unfolds Hen Egg White Lysozyme: Experimental and In Silico Approaches to Study the Interaction

AbstractHemin is an important iron‐containing porphyrin that has important therapeutic properties to control the symptoms of porphyria attacks that include pain, high blood pressure, rapid heartbeat, mental changes, and so forth. Lysozyme has many applications, which include from therapeutic to preservation of foods. The interaction of hemin with an important model protein, hen egg white lysozyme (HEWL), has been observed in this study through hybrid in silico with biophysical studies. There was a strong 1:1 cooperative binding between hemin and HEWL, which was revealed from the strong quenching of the latter by the former. The binding was favored by the decrease in temperature, which is due to the involvement of static type of quenching mechanism in the interaction. Experimental analyses suggested that the major forces involved in the binding were polar ones, and there was an efficient energy transfer from the fluorophore to the ligand. The combination of far‐UV CD spectroscopy and Rayleigh light scattering experiments established that hemin has the strong tendency to unfold HEWL. An extensive molecular docking investigation involving 2000 docking runs recognized the preferred binding site of hemin within HEWL, and also suggested that apart from the polar forces, hydrophobic interactions have also played an important role in the binding.

Carboxylic Group Functionalized Carbon Quantum Dots inhibit Hen Egg White Lysozyme Amyloidogenesis, leading to the Formation of Spherical Aggregates with Reduced Toxicity and ROS Generation.

Proteinopathies are a group of diseases where the protein structure has been altered. These alterations are linked to the production of amyloids, which are persistent, organized clumps of protein molecules through inter-molecular interactions. Several disorders, including Alzheimer's and Parkinson's, have been related to the presence of amyloids. Highly ordered beta sheets or beta folds are characteristic of amyloids; these structures can further self- assemble into stable fibrils. Protein aggregation is caused by a wide variety of environmental and experimental factors, including mutations, high pH, high temperature, and chemical modification. Despite several efforts, a cure for amyloidosis has yet to be found. Due to its advantageous semi-conducting characteristics, unique optical features, high surface area-to-volume ratio, biocompatibility, etc., carbon quantum dots (CQDs) have lately emerged as key instruments for a wide range of biomedical applications. To this end, we have investigated the effect of CQDs with a carboxyl group on their surface (CQD-CA) on the in vitro amyloidogenesis of hen egg white lysozyme (HEWL). By generating a stable compound that is resistant to fibrillation, our findings show that CQD-CA can suppress amyloid and disaggregate HEWL. In addition, CQD-CA caused the creation of non-toxic spherical aggregates, which generated much less reactive oxygen species (ROS). Overall, our results show that more research into amyloidosis treatments, including surface functionalized CQDs, is warranted.

Effects of preservatives on the activities of salivary enzymes

ObjectivesTo investigate the effects of common preservatives used in oral health care products on the enzymatic activities of lysozyme, peroxidase, and α-amylase in-solution and on-hydroxyapatite surface phases. DesignThe preservatives used in this study were sodium benzoate, methylparaben, propylparaben, and benzalkonium chloride. Hen egg-white lysozyme, bovine lactoperoxidase, and α-amylase from Bacillus sp. served as sources of purified enzymes. Human unstimulated whole saliva was used as a source of salivary enzymes. Hydroxyapatite beads were used as the surface phase. The preservatives were incubated with purified enzymes or saliva samples in-solution or on-hydroxyapatite surface phases, respectively. Enzymatic activities of lysozyme, peroxidase, and α-amylase were measured by hydrolysis of fluorescein-labelled Micrococcus lysodeikticus, oxidation of fluorogenic 2′,7′-dichlorofluorescin, and hydrolysis of fluorogenic starch, respectively. ResultsThe effects of the preservatives on the enzymatic activities of lysozyme and peroxidase were more distinct in the saliva samples than purified substances, and in the in-solution phase than on-hydroxyapatite surface phase, and the opposite was true for α-amylase. The most significant result was apparent decrease in peroxidase activities caused by the parabens in the in-solution phase (P<0.05). Sodium benzoate and parabens inhibited lysozyme activity in the in-solution phase, but differently for the purified and salivary lysozymes. Parabens and benzalkonium chloride inhibited the enzymatic activity of α-amylase from Bacillus sp., not saliva samples, only on-hydroxyapatite surface (P<0.05). ConclusionsEach preservative affected the enzymatic activities of lysozyme, peroxidase, and α-amylase differently. Based on the effects on salivary enzymes, sodium benzoate or benzalkonium chloride was recommended as preservatives rather than parabens.

A structural rationale for reversible vs irreversible amyloid fibril formation from a single protein.

Reversible and irreversible amyloids are two diverging cases of protein (mis)folding associated with the cross-β motif in the protein folding and aggregation energy landscape. Yet, the molecular origins responsible for the formation of reversible vs irreversible amyloids have remained unknown. Here we provide evidence at the atomic level of distinct folding motifs for irreversible and reversible amyloids derived from a single protein sequence: human lysozyme. We compare the 2.8 Å structure of irreversible amyloid fibrils determined by cryo-electron microscopy helical reconstructions with molecular insights gained by solid-state NMR spectroscopy on reversible amyloids. We observe a canonical cross-β-sheet structure in irreversible amyloids, whereas in reversible amyloids, there is a less-ordered coexistence of β-sheet and helical secondary structures that originate from a partially unfolded lysozyme, thus carrying a "memory" of the original folded protein precursor. We also report the structure of hen egg-white lysozyme irreversible amyloids at 3.2 Å resolution, revealing another canonical amyloid fold, and reaffirming that irreversible amyloids undergo a complete conversion of the native protein into the cross-β structure. By combining atomic force microscopy, cryo-electron microscopy and solid-state NMR, we show that a full unfolding of the native protein precursor is a requirement for establishing irreversible amyloid fibrils.

Modulation of AIE and Intramolecular Charge Transfer of a Pyrene-Based Probe for Discriminatory Detection and Imaging of Oligomers and Amyloid Fibrils.

Oligomers and amyloid fibrils formed at different stages of protein aggregation are important biomarkers for a variety of neurodegenerative diseases including Alzheimer's and Parkinson's diseases. The development of probes for the sensitive detection of oligomeric species is important for early stage diagnosis of amyloidogenic diseases. Many small molecular dyes have been developed to probe the dynamic growth of amyloid fibrils. However, there is a lack of discriminatory detection strategies to monitor the dynamics of both oligomers and amyloid fibrils based on the differential modulation of the photophysical properties of a single dye. Here we report a pyrene-based intramolecular charge transfer (ICT) dye with large Stokes shifted red-emitting aggregation induced emission (AIE) for monitoring the dynamic populations of both oligomers and fibrils during the aggregation of hen egg white lysozyme (HEWL) protein. At the early stage of protein aggregation, the accumulation of HEWL oligomers results in a rapid and substantial increase in the red AIE intensity at 660 nm. Later, as the oligomers transform into mature fibrils, the dye exhibits a distinct photophysical change. Binding of the dye to HEWL fibrils strongly suppresses the red AIE and enhances ICT emission. This is evidenced by a gradual decrease in the AIE intensity (∼660 nm) and an increase in LE (∼490 nm) and ICT (∼540 nm) emission intensities during the later stages of protein aggregation. Thus, the dye provides simultaneous measurements of the population dynamics of both HEWL oligomers and fibrils during protein aggregation based on the discriminatory modulation of AIE and ICT of the dye. The dye also enables imaging of both HEWL oligomers and fibrils simultaneously using different emission channels in super-resolution confocal fluorescence microscopy.

PSLBII-17 Supplementation with organic versus inorganic selenium during pregnancy to support ewe and lamb health

Abstract Selenium (Se) is essential for optimal ovine health and production, and sheep raised on Se-deficient soils can be vulnerable to Se deficiencies that can affect immune function. Organic or inorganic forms of Se supplementation can remedy these consequences. While inorganic Se is less costly, organic Se is more bioavailable and may be more efficient in providing Se to ewes and lambs. The objectives of this study were to determine how organic versus inorganic Se supplementation affects ewe Se status, Se transfer from ewes to lambs, and the antibody-mediated immune response and dermal hypersensitivity response (DHR) of ewes and their lambs. Dorset-Rideau ewes (n = 100) were enrolled in a randomized complete block design study. From gestation d (gd) 110 to postpartum d (ppd) 50, ewes were fed either a Se-deficient diet and supplemented with no Se, 0.3 mg inorganic Se, or 0.3 mg or 0.6 mg organic Se. Sera were collected on gd 110, 130, 140, and ppd 10 and 50 to determine ewe Se status. On gd 110 and 120, ewes received an intramuscular injection of 0.5 mg ovalbumin (OVA) antigen, and on gd 130 the DHR to OVA was assessed by measuring change in skinfold thickness 0, 6, 24 and 48 h post intradermal injection. To measure the transfer of Se from ewe to lamb, a subset of lambs was euthanized at ppd 10, and longissimus dorsi muscle samples were collected and analyzed for Se content. On ppd 20 and 30, lambs received an intramuscular injection of 0.5 mg hen egg white lysozyme (HEWL) antigen, and on ppd 40 the DHR to HEWL was assessed using the aforementioned protocol. Analysis of ewe sera showed a positive correlation between organic Se supplementation and greater Se concentrations (P &amp;lt; 0.01). Moreover, statistical analyses of the DHR results using a generalized least squares linear model (RStudio) indicate that Se supplementation increased the immune response compared with the non-supplemented ewes (P &amp;lt; 0.01). However, no significant differences between organic and inorganic Se supplementation were found. In lambs, greater ewe Se supplementation resulted in greater Se muscle content (P &amp;gt; 0.01). and organic Se supplementation to ewes significantly increased lamb Se muscle content compared with inorganic Se supplementation (P &amp;gt; 0.01). Finally, analyses of the lamb DHR showed that maternal organic Se supplementation improved the lamb immune response compared with the control group (P &amp;gt; 0.05). Therefore, organic Se supplementation optimally enhances ewe and lamb Se status and their adaptive immune response compared with the inorganic and control groups. This knowledge will guide optimal ewe Se-supplementation choices during pregnancy and postpartum, thus promoting lamb and ewe health.

Concentration effect of zinc ions on amyloid fibrillation of hen egg-white lysozyme with thermal treatment revealed by Raman spectroscopy

Accumulation of Zn2+ ions in protein aggregates has been suggested to be a key factor in Alzheimer’s disease etiology. However, the specific influence of Zn2+ ions on the formation of amyloid fibrils or amorphous aggregates is still much debated. Herein, we conducted a combined study of Raman spectroscopy, UV–vis absorption spectroscopy and ThT fluorescence assay on the concentration effects of Zn2+ ions on amyloid fibrillation of hen egg-white lysozyme with thermal treatment. The addition of Zn2+ ions showed a negligible effect on unfolding of the protein tertiary structures and nucleation pathways on amyloid fibrillation. In contrast, a distinct concentration-dependence was observed for the influence of Zn2+ ions on the transformation of lysozyme secondary structures. At low concentration, the metal ions do not affect the populations of major secondary structures in the final state after incubation, while they at high concentration exhibit a promotion effect on the transformation from α-helix to β-sheet-like structures. These findings provide insights into the multifaceted impact of Zn2+ ions on protein aggregation, shedding light on potential therapeutic strategies for neurodegenerative diseases.

The volatile constituents of rose, saffron and cardamom suppress the fibrillation of tau and not HEWL through the formation of non-toxic tau oligomers

The formation of fibrillar structures of tau is correlated with taupathies including Alzheimer's disease (AD). This study has aimed to find ways to prevent tau fibril formation. Here, we used dietary compounds including cinnamon (CN), damask rose (Rose), saffron (Saf) and green cardamom (Car), to evaluate the effects of their volatile constituents, on hen egg white lysozyme (HEWL), as a model protein (commonly used for fibrillation studies), as well as the brain-related tau protein. The study was done using different spectroscopic techniques as well as SDS-PAGE, AFM and MTT assay. While the results suggested that the volatile constituents were unable to prevent HEWL fibril formation, most of the dietary compounds, in particular Saf, Rose and Car, were able to interfere with the mature fibril formation, by either maintaining the native form of tau or resulting in the entrapment of non-toxic oligomeric forms of tau. Moreover, the neurotoxicity analysis of tau samples on neuroblastoma SH-SY5Y cells indicated that tau treated with Saf, Rose and Car were the least toxic. Overall, the findings indicate that the potential therapeutic impacts of the volatile constituents of Rose, Car and in particular Saf, may demonstrate significant efficacy in addressing neurodegenerative diseases such as AD.

Real-time observation of a metal complex-driven reaction intermediate using a porous protein crystal and serial femtosecond crystallography

Determining short-lived intermediate structures in chemical reactions is challenging. Although ultrafast spectroscopic methods can detect the formation of transient intermediates, real-space structures cannot be determined directly from such studies. Time-resolved serial femtosecond crystallography (TR-SFX) has recently proven to be a powerful method for capturing molecular changes in proteins on femtosecond timescales. However, the methodology has been mostly applied to natural proteins/enzymes and limited to reactions promoted by synthetic molecules due to structure determination challenges. This work demonstrates the applicability of TR-SFX for investigations of chemical reaction mechanisms of synthetic metal complexes. We fix a light-induced CO-releasing Mn(CO)3 reaction center in porous hen egg white lysozyme (HEWL) microcrystals. By controlling light exposure and time, we capture the real-time formation of Mn-carbonyl intermediates during the CO release reaction. The asymmetric protein environment is found to influence the order of CO release. The experimentally-observed reaction path agrees with quantum mechanical calculations. Therefore, our demonstration offers a new approach to visualize atomic-level reactions of small molecules using TR-SFX with real-space structure determination. This advance holds the potential to facilitate design of artificial metalloenzymes with precise mechanisms, empowering design, control and development of innovative reactions.

Protonation-State Dependent Modulation of Hen Egg-White Lysozyme Fibrillation under the Influence of a Short Synthetic Peptide.

Under the influence of various conditions, misfolding of soluble proteins occurs, leading to the formation of toxic insoluble amyloids. The formation and deposition of such amyloids within the body are associated with detrimental biological consequences such as the onset of several amyloid-related diseases. Previously, we established a strategy for the rational design of peptide inhibitors against amyloid formation based on the amyloidogenic-prone region of the protein. In the current study, we have designed and identified an Asp-containing rationally designed hexapeptide (SqP4) as an excellent inhibitor of hen egg-white lysozyme (HEWL) amyloid progression in vitro. First, SqP4 showed strong affinity toward the native monomeric HEWL leading to the stabilization of the native form and restriction in the unfolding process of monomeric HEWL. Second, SqP4 was found to arrest the amyloidogenic misfolded structure of HEWL in a nonfibrillar monomer-like stage. We also observed the differential effect of the protonation state of the charged amino acid (Asp) within the peptide inhibitor on the amyloid formation of HEWL and explored the reason behind the observations. The findings of this study can be implemented in future strategies for the development of potent therapeutics against other amyloid-related diseases.

Protein-Protein Stabilization in VIVO/8-Hydroxyquinoline-Lysozyme adduct: A Spectroscopic, Crystallographic, and Computational Study.

The binding of the potential drug[VIVO(8-HQ)2], where 8-HQ is 8-hydroxyquinolinato, with hen egg white lysozyme (HEWL) was evaluated through spectroscopic (electron paramagnetic resonance, EPR, and UV-visible), spectrometric (electrospray ionization-mass spectrometry, ESI-MS), crystallographic (X-ray diffraction, XRD), and computational (DFT and docking) studies. ESI-MS indicates the interaction of [VIVO(8-HQ)(H2O)]+ and [VIVO(8-HQ)2(H2O)] species with HEWL. Room temperature EPR spectra suggest both covalent and non-covalent binding of the two different V-containing fragments. XRD analyses confirm these findings, showing that [VIVO(8-HQ)(H2O)]+ interacts covalently with the solvent exposed Asp119, while cis-[VIVO(8-HQ)2(H2O)] non-covalently with Arg128 and Lys96 from a symmetry mate. The covalent binding of [VIVO(8-HQ)(H2O)]+ to Asp119 is favored by a π-π contact with Trp62 and a H-bond with Asn103 of a symmetry-related molecule. Additionally, the covalent binding of VVO2+ to Asp48 and non-covalent binding of other V-containing fragments to Arg5, Cys6, and Glu7 is revealed. Molecular docking indicates that, in the absence of the interactions occurring at the protein-protein interface close to Asp119, the binding to Glu35 or Asp52 should be preferred. Such a protein-protein stabilization could be more common than what believed up today, at least in the solid state, and should be considered in the characterization of metal-protein adducts.

Mechanistic exploration of Perfluorooctanoic Acid-Induced Hen egg white lysozyme aggregation at physiological Conditions: Spectroscopic and thermodynamic insights

Perfluoroalkyl substances (PFASs) have garnered attention in various scientific fields for their harmful effects on biological systems, including the endocrine, immune, and nervous systems. While research has delved into PFAS-protein binding, their impact on protein aggregation remains uncharted. In this study, we investigated the effect of perfluorooctanoic acid (PFOA) on the aggregation of Hen Egg White Lysozyme (HEWL), a model protein known to aggregate under harsh conditions. We uncovered compelling insights by employing an array of spectroscopic, computational and thermal techniques. Isothermal titration calorimetry (ITC), molecular docking, and fluorescence spectroscopy reveal strong PFOA-HEWL interactions via hydrogen bonding, hydrophobic forces, and ionic interactions. Moreover, techniques like synchronous fluorescence spectroscopy, circular dichroism, and FTIR demonstrates that PFOA induces substantial conformational changes in HEWL, profoundly affecting its secondary structure. Increased PFOA concentrations have been observed to lead to HEWL aggregation under physiological conditions (pH 7.4 and room temperature), verified through various assays and imaging techniques. This is the first comprehensive exploration of PFOA’s influence on protein aggregation. Our findings provide valuable insights into the health risks of PFOA exposure from a protein aggregation perspective, advancing our knowledge in environmental ecology, toxicology, pathology, and life sciences.

Isoflavones and lysozyme interplay: Molecular insights into binding mechanisms and inhibitory efficacies of isoflavones against protein modification

In this study, we investigated the complexation of bioactive isoflavones, specifically biochanin A (BCA) and genistein (GEN), with hen egg white lysozyme (HEWL) and explored their inhibitory effects on HEWL modification using a combination of multi-spectroscopic and computational methods. The observed binding affinity was of a moderate nature (on the order of 104 M−1), and a static quenching mechanism was identified in the fluorescence quenching process. Notably, the binding constant (Kb) for GEN (4.449 ± 0.262 × 104 M−1) was found to be higher than that for BCA (3.707 ± 0.108 × 104 M−1) towards HEWL. Our spectroscopic measurements, complemented by molecular docking calculations, suggested the involvement of Trp62 in the binding site of the isoflavones within the geometry of HEWL. The micro-environment surrounding the Trp-residues exhibited an increase in hydrophilicity, as indicated by Synchronous fluorescence (SFS) and three-dimensional fluorescence (3D) studies. Interestingly, circular dichroism (CD) studies revealed no marked alteration in the secondary structure of HEWL upon binding with the isoflavones. Furthermore, our investigation into the interaction patterns, employing FTIR and molecular docking studies, revealed a predominance of hydrogen bonding and hydrophobic interactions. Beyond the binding study, the isoflavones demonstrated a promising inhibitory effect on the d-ribose-mediated glycation of HEWL, as well as on HEWL fibrillation, as evidenced by fluorescence emission studies. Our findings not only exhibited an excellent correlation with experimental observations but also provided precise insights into the location and dynamics of isoflavones within the binding site through detailed analyses of molecular docking and molecular dynamics simulation data.

Influence of Chemical Modifications of the Crystallophore on Protein Nucleating Properties and Supramolecular Interactions Network.

Crystallophores are lanthanide complexes that have demonstrated outstanding induction of crystallization for various proteins. This article explores the effect of tailored modifications of the crystallophore first generation and their impact on the nucleating properties and protein crystal structures. Through high-throughput crystallization experiments and dataset analysis, we evaluated the effectiveness of these variants, in comparison to the first crystallophore generation G1. In particular, the V1 variant, featuring a propanol pendant arm, demonstrated the ability to produce new crystallization conditions for the proteins tested (hen-egg white lysozyme, proteinase K and thaumatin). Structural analysis performed in the case of hen egg-white lysozyme along with Molecular Dynamics simulations, highlights V1's unique behavior, taking advantage of the flexibility of its propanol arm to explore different protein surfaces and form versatile supramolecular interactions.

Graphene acid quantum dots: A highly active multifunctional carbon nano material that intervene in the trajectory towards neurodegeneration

Carbon dots (CDs) are carbon nano materials (CNMs) that find use across several biological applications because of their water solubility, biocompatible nature, eco-friendliness, and ease of synthesis. Additionally, their physiochemical properties can be chemically tuned for further optimization towards specific applications. Here, we investigate the efficacy of C70-derived Graphene Acid Quantum Dots (GAQDs) in mitigating the transformation of soluble, monomeric Hen Egg-White Lysozyme (HEWL) to mature fibrils during its amyloidogenic trajectory. Our findings reveal that GAQDs exhibit dose-dependent inhibition of HEWL fibril formation (up to 70 % at 5 mg/mL) without affecting mitochondrial membrane potential or inducing apoptosis at the same density. Furthermore, GAQDs scavenged reactive oxygen species (ROS); achieving a 50 % reduction in ROS levels at a mere 100 µg/mL when exposed to a standard free radical generator. GAQDs were not only found to be biocompatible with a human neuroblastoma-derived SHSY-5Y cell line but also rescued the cells from rotenone-induced apoptosis. The GAQD-tolerance of SHSY-5Y cells coupled with their ability to restitute cells from rotenone-dependent apoptosis, when taken in conjunction with the biocompatibility data, indicate that GAQDs possess neuroprotective potential. The data position this class of CNMs as promising candidates for resolving aberrant cellular outputs that associate with the advent and progress of multifactorial neurodegenerative disorders including Parkinson’s (PD) and Alzheimer’s diseases (AD) wherein environmental causes are implicated (95 % etiology). The data suggest that GAQDs are a multifunctional carbon-based sustainable nano-platform at the intersection of nanotechnology and neuroprotection for advancing green chemistry-derived, sustainable healthcare solutions.

A small angle X-ray scattering study comparing protic ionic liquid solvent effects on the solution behaviors of hen egg white and human lysozyme

Proteins demand customized solvents for maintaining their stability. However, the specific impact of different ions on different proteins remains unclear. This study explores the effects of protic ionic liquid (PIL)-based solvents on two structurally similar proteins, namely hen egg white and human lysozyme. By employing size exclusion chromatography small-angle X-ray scattering (SEC-SAXS) and capillary SAXS, the effects of protein concentration (3 to 60 mg/mL), IL type (five PILs) and concentration (1, 10 and 20 mol% with water) and protein type on the aggregation behavior and radius of gyration (Rg) of the two lysozymes were studied. HEWL was mostly monomeric in buffer and solubilized beyond 20 mg/mL, while HL displayed slight aggregation in buffer but had increased aggregation at over 10 mg/mL. Further capillary SAXS data show that both proteins became more aggregated at concentrations exceeding 20 mg/mL and over 1 mol% PILs. The nitrate anion generally showed the “salting in” effect, while formate and glycolate anions induced the “salting out” effect on the two proteins. Overall, anion selection and protein solution behaviors at protein concentration of over 20 mg/mL and at 20 mol% ILs can be critical for maintaining the lysozyme stability.

Interfacial Interactions between Nanoplastics and Biological Systems: toward an Atomic and Molecular Understanding of Plastics-Driven Biological Dyshomeostasis.

Micro- and nano-plastics (NPs) are found in human milk, blood, tissues, and organs and associate with aberrant health outcomes including inflammation, genotoxicity, developmental disorders, onset of chronic diseases, and autoimmune disorders. Yet, interfacial interactions between plastics and biomolecular systems remain underexplored. Here, we have examined experimentally, in vitro, in vivo, and by computation, the impact of polystyrene (PS) NPs on a host of biomolecular systems and assemblies. Our results reveal that PS NPs essentially abolished the helix-content of the milk protein β-lactoglobulin (BLG) in a dose-dependent manner. Helix loss is corelated with the near stoichiometric formation of β-sheet elements in the protein. Structural alterations in BLG are also likely responsible for the nanoparticle-dependent attrition in binding affinity and weaker on-rate constant of retinol, its physiological ligand (compromising its nutritional role). PS NP-driven helix-to-sheet conversion was also observed in the amyloid-forming trajectory of hen egg-white lysozyme (accelerated fibril formation and reduced helical content in fibrils). Caenorhabditis elegans exposed to PS NPs exhibited a decrease in the fluorescence of green fluorescent protein-tagged dopaminergic neurons and locomotory deficits (akin to the neurotoxin paraquat exposure). Finally, in silico analyses revealed that the most favorable PS/BLG docking score and binding energies corresponded to a pose near the hydrophobic ligand binding pocket (calyx) of the protein where the NP fragment was found to make nonpolar contacts with side-chain residues via the hydrophobic effect and van der Waals forces, compromising side chain/retinol contacts. Binding energetics indicate that PS/BLG interactions destabilize the binding of retinol to the protein and can potentially displace retinol from the calyx region of BLG, thereby impairing its biological function. Collectively, the experimental and high-resolution in silico data provide new insights into the mechanism(s) by which PS NPs corrupt the bimolecular structure and function, induce amyloidosis and onset neuronal injury, and drive aberrant physiological and behavioral outcomes.