Protonation favors aggregation of lysozyme with SDS

Degradation of pathogenic amyloids induced by matrix metalloproteinase-9

Over the past decade, the greatest promise for treating severe and currently incurable systemic and neurodegenerative diseases has turned to agents capable of effectively degrading pathological amyloid deposits without causing side effects. Specifically, amyloid destruction observed in immunotherapy is hypothesized to occur through activation of proteolytic enzymes. This study examines poorly understood effects of an immune enzyme, extracellular matrix metalloproteinase-9 (MMP9), on amyloids associated with Alzheimer's and Parkinson's diseases, lysozyme, insulin, and dialysis-related amyloidoses. The study establishes the universality of MMP9's effect on various amyloids, with its efficacy largely depending on the fibrillar cluster size. Irreversible amyloid degradation by MMP9 is attributed to the destruction of intramolecular interactions rather than intermolecular hydrogen bonds in the fibril backbone. This process results in the loss of ordered fiber structure without reducing aggregate size or increasing cytotoxicity. Thus, MMP9 can mitigate side effects of anti-amyloid therapy associated with the formation of low-molecular-weight degradation products that may accelerate fibrillogenesis and amyloid propagation between tissues and organs. MMP9 shows promise as a component of safe anti-amyloid drugs by enhancing the accessibility of binding sites through "loosening" amyloid clusters, which facilitates subsequent fragmentation and monomerization by other enzymes.

Molecular insights into the phase transition of lysozyme into amyloid nanostructures: Implications of therapeutic strategies in diverse pathological conditions

Lysozyme, a well-known bacteriolytic enzyme, exhibits a fascinating yet complex behavior when it comes to protein aggregation. Under certain conditions, this enzyme undergoes flexible transformation, transitioning from partially unfolded intermediate units of native conformers into complex cross-β-rich nano fibrillar amyloid architectures. Formation of such lysozyme amyloids has been implicated in a multitude of pathological and medical severities, like hepatic dysfunction, hepatomegaly, splenic rupture as well as spleen dysfunction, nephropathy, sicca syndrome, renal dysfunction, renal amyloidosis, and systemic amyloidosis. In this comprehensive review, we have attempted to provide in-depth insights into the aggregating behavior of lysozyme across a spectrum of variables, including concentrations, temperatures, pH levels, and mutations. Our objective is to elucidate the underlying mechanisms that govern lysozyme's aggregation process and to unravel the complex interplay between its structural attributes. Moreover, this work has critically examined the latest advancements in the field, focusing specifically on novel strategies and systems, that have been implemented to delay or inhibit the lysozyme amyloidogenesis. Apart from this, we have tried to explore and advance our fundamental understanding of the complex processes involved in lysozyme aggregation. This will help the research community to lay a robust foundation for screening, designing, and formulating targeted anti-amyloid therapeutics offering improved treatment modalities and interventions not only for lysozyme-linked amyloidopathy but for a wide range of amyloid-related disorders.

Delicate Analysis of Interacting Proteins and Their Assemblies by Flow Field-Flow Fractionation Techniques

We study the efficiency of several asymmetrical flow field-flow fractionation (AF4) techniques to investigate self-associating wheat gluten proteins. We compare the use of a denaturing buffer including sodium dodecyl sulfate (SDS) and a mild chaotropic solvent, water/ethanol, as the eluent, on a model gluten sample. Through a thorough analysis of the data obtained from coupled light scattering detectors and with the identification of molecular composition of the eluted protein, we evidence coelution events in several conditions. We show that the focus step used in conventional AF4 with the SDS buffer leads to the formation of aggregates that coelute with monomeric proteins. By contrast, a frit-inlet device enables the fractionation of individual wheat proteins in the SDS buffer. Interestingly conventional AF4, using water/ethanol as eluent, is an effective method for fractionating gluten proteins and their complex dynamic assemblies, which involve weak forces and are composed of both monomeric and polymeric proteins.

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.

Investigating the binding interaction of quinoline yellow with bovine serum albumin and anti-amyloidogenic behavior of ferulic acid on QY-induced BSA fibrils

Protein aggregation induces profound changes in the structure along with the conformation of the protein, and is responsible for the pathogenesis of a number of neurodegenerative conditions such as Huntington's, Creutzfeldt-Jacob, Type II diabetes mellitus, Alzheimer's, etc. Numerous multi-spectroscopic approaches and in-silico experiments were utilized to investigate BSA's biomolecular interaction and aggregation in the presence of quinoline yellow. The present research investigation evaluated the interaction of BSA with the food colorant (QY) at two different pH (7.4 and 2.0). The development of the BSA-QY complex was established with UV visible and fluorescence spectroscopy. The quenching of fluorescence upon the interaction of BSA with QY revealed the static nature of quenching mechanism. The Kb value obtained from our result is 4. 54 × 10-4 M-1. The results from the competitive site marker study infer that quinoline yellow is binding with the sub-domain IB of bovine serum albumin, specifically on site III. Three-dimensional fluorescence and synchronous fluorescence spectroscopy were applied for monitoring the alterations in the microenvironment of BSA upon the addition of quinoline yellow. The results from turbidity and RLS studies showed that higher concentrations of QY (80-400 µM) triggered bovine serum albumin (BSA) aggregation at pH 2.0. At pH 7.4, QY couldn't manage to trigger bovine serum albumin aggregation, perhaps because of the repulsion between negatively charged dye (QY) and anionic bovine serum albumin. The results from far-UV CD, Congo Red, and scanning electron microscopy implicate that the QY-induced aggregates exhibit amyloid fibril-like structures. Molecular docking results revealed that hydrophobic interactions, hydrogen bonding, and Pi-Sulfur interactions contribute to QY-induced aggregation of BSA. Further, the amyloid inhibitory potential of ferulic acid (FA), a phenolic acid on QY-induced aggregation of BSA, has also been assessed. The QY-induced amyloid fibrils are FA-soluble, as confirmed by turbidity, RLS, and far-UV CD studies. Far-UV CD results showed that FA retains α helix and inhibits cross β sheet formation when the BSA samples were pre-incubated with increasing concentrations of FA (0-500 µM). Our findings conclude that QY dye successfully stimulates BSA aggregation, but ferulic acid inhibits QY-induced aggregation of BSA. Thus, FA can serve as a therapeutic agent and can help in the treatment of various amyloid-related conditions.

Insights into the interaction and inhibitory action of palmatine on lysozyme fibrillogenesis: Spectroscopic and computational studies

Interaction under amyloidogenic condition between naturally occurring protoberberine alkaloid palmatine and hen egg white lysozyme was executed by adopting spectrofluorometric and theoretical molecular docking and dynamic simulation analysis. In spetrofluorometric method, different types of experiments were performed to explore the overall mode and mechanism of interaction. Intrinsic fluorescence quenching of lysozyme (Trp residues) by palmatine showed effective binding interaction and also yielded different binding parameters like binding constant, quenching constant and number of binding sites. Synchronous fluorescence quenching and 3D fluorescence map revealed that palmatine was able to change the microenvironment of the interacting site. Fluorescence life time measurements strongly suggested that this interaction was basically static in nature. Molecular docking result matched with fluorimetric experimental data. Efficient drug like interaction of palmatine with lysozyme at low pH and high salt concentration prompted us to analyze its antifibrillation potential. Different assays and microscopic techniques were employed for detailed analysis of lysozyme amyloidosis.Thioflavin T(ThT) assay, Congo Red (CR) assay, 8-anilino-1-naphthalenesulfonic acid (ANS) assay, Nile Red (NR) assay, anisotropy and intrinsic fluorescence measurements confirmed that palmatine successfully retarded and reduced lysozyme fibrillation. Dynamic light scattering (DLS) and atomic force microscopy (AFM) further reiterated the excellent antiamyloidogenic potency of palmatine.

Probing the interaction mechanisms between sunset yellow dye and trypsin protein leading to amorphous aggregation under low pH conditions

Protein aggregation poses a significant concern in the field of food sciences, and various factors, such as synthetic food dyes, can contribute to protein aggregation. One such dye, Sunset Yellow (SY), is commonly employed in the food industry. Trypsin was used as a model protein to assess the impact of SY. We employed several biophysical techniques to examine the binding and aggregation mechanisms between SY and trypsin at different pHs. Results from intrinsic fluorescence measurements indicate a stronger interaction between SY and trypsin at pH 2.0 compared to pH 6.0. Turbidity data reveal trypsin aggregation in the presence of 0.05-3.0 mM SY at pH 2.0, while no aggregation was observed at pH 6.0. Kinetic data demonstrate a rapid, lag-phase-free SY-induced aggregation of trypsin. Circular dichroism analysis reveals that trypsin adopts a secondary structure in the presence of SY at pH 6.0, whereas at pH 2.0, the secondary structure was nearly lost with increasing SY concentrations. Furthermore, turbidity and kinetics data suggest that trypsin aggregation depends on trypsin concentrations and pH. Our study highlights potential health risks associated with the consumption of SY, providing insights into its impact on human health and emphasizing the necessity for further research in this field.

Evaluating and optimizing Acid-pH and Direct Lysis RNA extraction for SARS-CoV-2 RNA detection in whole saliva

COVID-19 has been a global public health and economic challenge. Screening for the SARS-CoV-2 virus has been a key part of disease mitigation while the world continues to move forward, and lessons learned will benefit disease detection beyond COVID-19. Saliva specimen collection offers a less invasive, time- and cost-effective alternative to standard nasopharyngeal swabs. We optimized two different methods of saliva sample processing for RT-qPCR testing. Two methods were optimized to provide two cost-efficient ways to do testing for a minimum of four samples by pooling in a 2.0 mL tube and decrease the need for more highly trained personnel. Acid-pH-based RNA extraction method can be done without the need for expensive kits. Direct Lysis is a quick one-step reaction that can be applied quickly. Our optimized Acid-pH and Direct Lysis protocols are reliable and reproducible, detecting the beta-2 microglobulin (B2M) mRNA in saliva as an internal control from 97 to 96.7% of samples, respectively. The cycle threshold (Ct) values for B2M were significantly higher in the Direct Lysis protocol than in the Acid-pH protocol. The limit of detection for N1 gene was higher in Direct Lysis at ≤ 5 copies/μL than Acid-pH. Saliva samples collected over the course of several days from two COVID-positive individuals demonstrated Ct values for N1 that were consistently higher from Direct Lysis compared to Acid-pH. Collectively, this work supports that each of these techniques can be used to screen for SARS-CoV-2 in saliva for a cost-effective screening platform.

Impact of Sinapic Acid on Bovine Serum Albumin Thermal Stability

The thermal stability of bovine serum albumin (BSA) in Tris buffer, as well as the effect of sinapic acid (SA) on protein conformation were investigated via calorimetric (differential scanning microcalorimetry-μDSC), spectroscopic (dynamic light scattering-DLS; circular dichroism-CD), and molecular docking approaches. μDSC data revealed both the denaturation (endotherm) and aggregation (exotherm) of the protein, demonstrating the dual effect of SA on protein thermal stability. With an increase in ligand concentration, (i) protein denaturation shifts to a higher temperature (indicating native form stabilization), while (ii) the aggregation process shifts to a lower temperature (indicating enhanced reactivity of the denatured form). The stabilization effect of SA on the native structure of the protein was supported by CD results. High temperature (338 K) incubation induced protein unfolding and aggregation, and increasing the concentration of SA altered the size distribution of the protein population, as DLS measurements demonstrated. Complementary information offered by molecular docking allowed for the assessment of the ligand binding within the Sudlow's site I of the protein. The deeper insight into the SA-BSA interaction offered by the present study may serve in the clarification of ligand pharmacokinetics and pharmacodynamics, thus opening paths for future research and therapeutic applications.

Sugar osmolyte inhibits and attenuates the fibrillogenesis in RNase A: An in vitro and in silico characterizations

Mechanisms of protein aggregation are of immense interest in therapeutic biology and neurodegenerative medicine. Biochemical processes within the living cell occur in a highly crowded environment. The phenomenon of macromolecular crowding affects the diffusional and conformational dynamics of proteins and modulates their folding. Macromolecular crowding is reported to cause protein aggregation in some cases, so it is a cause of concern as it leads to a plethora of neurodegenerative disorders and systemic amyloidosis. To divulge the mechanism of aggregation, it is imperative to study aggregation in well-characterized model proteins in the presence of macromolecular crowder. One such protein is ribonuclease A (RNase A), which deciphers neurotoxic function in humans; therefore we decided to explore the amyloid fibrillogenesis of this thermodynamically stable protein. To elucidate the impact of crowder, dextran-70 and its monomer glucose on the aggregation profile of RNase-A various techniques such as Absorbance, Fluorescence, Fourier Transforms Infrared, Dynamic Light Scattering and circular Dichroism spectroscopies along with imaging techniques like Atomic Force Microscopy and Transmission Electron Microscopy were employed. Thermal aggregation and fibrillation were further promoted by dextran-70 while glucose counteracted the effect of the crowding agent in a concentration-dependent manner. This study shows that glucose provides stability to the protein and prevents fibrillation. Intending to combat aggregation, which is the hallmark of numerous late-onset neurological disorders and systemic amyloidosis, this investigation unveils that naturally occurring osmolytes or other co-solutes can be further exploited in novel drug design strategies.

Solvent-Induced Lag Phase during the Formation of Lysozyme Amyloid Fibrils Triggered by Sodium Dodecyl Sulfate: Biophysical Experimental and In Silico Study of Solvent Effects

Amyloid aggregates arise from either the partial or complete loss of the native protein structure or the inability of proteins to attain their native conformation. These aggregates have been linked to several diseases, including Alzheimer's, Parkinson's, and lysozyme amyloidosis. A comprehensive dataset was recently reported, demonstrating the critical role of the protein's surrounding environment in amyloid formation. In this study, we investigated the formation of lysozyme amyloid fibrils induced by sodium dodecyl sulfate (SDS) and the effect of solvents in the medium. Experimental data obtained through fluorescence spectroscopy revealed a notable lag phase in amyloid formation when acetone solution was present. This finding suggested that the presence of acetone in the reaction medium created an unfavorable microenvironment for amyloid fibril formation and impeded the organization of the denatured protein into the fibril form. The in silico data provided insights into the molecular mechanism of the interaction between acetone molecules and the lysozyme protofibril, once acetone presented the best experimental results. It was observed that the lysozyme protofibril became highly unstable in the presence of acetone, leading to the complete loss of its β-sheet conformation and resulting in an open structure. Furthermore, the solvation layer of the protofibril in acetone solution was significantly reduced compared to that in other solvents, resulting in fewer hydrogen bonds. Consequently, the presence of acetone facilitated the exposure of the hydrophobic portion of the protofibril, precluding the amyloid fibril formation. In summary, our study underscores the pivotal role the surrounding environment plays in influencing amyloid formation.

Mechanistic and biophysical insight into the inhibitory and disaggregase role of antibiotic moxifloxacin on human lysozyme amyloid formation

Lysozyme amyloidosis is a systemic non-neuropathic disease caused by the accumulation of amyloids of mutant lysozyme. Presently, therapeutic interventions targeting lysozyme amyloidosis, remain elusive with only therapy available for lysozyme amyloidosis being supportive management. In this work, we examined the effects of moxifloxacin, a synthetic fluoroquinolone antibiotic on the amyloid formation of human lysozyme. The ability of moxifloxacin to interfere with lysozyme amyloid aggregation was examined using various biophysical methods like Rayleigh light scattering, Thioflavin T fluorescence assay, transmission electron microscopy and docking method. The reduction in scattering and ThT fluorescence along with extended lag phase in presence of moxifloxacin, suggest that the antibiotic inhibits and impedes the lysozyme fibrillation in concentration dependent manner. From ANS experiment, we deduce that moxifloxacin is able to decrease the hydrophobicity of the protein molecule thereby preventing aggregation. Our CD and DLS results show that moxifloxacin stabilizes the protein in its native monomeric structure, thus also showing retention of lytic activity upto 69% and inhibition of cytotoxicity at highest concentration of moxifloxacin. The molecular docking showed that moxifloxacin forms a stable complex of -7.6 kcal/mol binding energy and binds to the aggregation prone region of lysozyme thereby stabilising it and preventing aggregation. Moxifloxacin also showed disaggregase potential by disrupting fibrils and decreasing the β-sheet content of the fibrils. Our current study, thus highlight the anti-amyloid and disaggregase property of an antibiotic moxifloxacin and hence sheds light on the future of antibiotics against protein aggregation, a hallmark event in many neurodegenerative diseases.

The effect of novel antihypertensive drug valsartan on lysozyme aggregation: A combined in situ and in silico study

Protein misfolding can result in amyloid fiber aggregation, which is associated with various types of diseases. Therefore, preventing or treating abnormally folded proteins may provide therapeutic intervention for these diseases. Valsartan (VAL) is an angiotensin II receptor blocker (ARB) that is used to treat hypertension. In this study, we examine the anti-aggregating effect of VAL against hen egg-white lysozyme (HEWL) amyloid fibrils through spectroscopy, docking, and microscopic analysis. In vitro formation of HEWL amyloid fibrils was indicated by increased turbidity, RLS (Rayleigh light scattering), and ThT fluorescence intensity. 10 μM VAL, amyloid/aggregation was inhibited up to 83% and 72% as measured by ThT and RLS respectively. In contrast, 100 μM VAL significantly increases the fibril aggregation of HEWL. CD spectroscopy results show a stabilization of HEWL α-helical structures in the presence of 10 μM VAL while the increase in β-sheet was detected at 100 μM concentration of VAL. The hydrophobicity of HEWL was increased at 100 μM VAL, suggesting the promotion of aggregation via its self-association. Steady-state quenching revealed that VAL and HEWL interact spontaneously via hydrogen bonds and van der Waals forces. Transmission electron microscopy (TEM) images illustrate that the needle-like fibers of HEWL amyloid were reduced at 10 μM VAL, while at 100 μM the fibrils of amyloid were increased. Additionally, our computational studies showed that VAL could bind to two binding sites within HEWL. In the BS-1 domain of HEWL, VAL binds to ASN⁵⁹, ILE⁹⁸, ILE⁵⁸, TRP¹⁰⁸, VAL¹⁰⁹, SER⁵⁰, ASP⁵², ASN⁵⁹, ALA¹⁰⁷, and TRP¹⁰⁸ residues with a binding energy of -9.72 kcal mol^-1. Also, it binds to GLU⁷, ALA¹⁰, ALA¹¹, CYS⁶, ARG¹²⁸, and ARG¹⁴ in the BS-2 domain with a binding energy of -5.89 kcal mol^-1. VAL, therefore, appears to have dual effect against HEWL aggregation. We suggest that VAL stabilizes HEWL's aggregation-prone region (APR) at 10 μM, preventing aggregation. Also, we assume that at 100 μM, VAL occupies BS-2 beside BS-1 and destabilizes the folding structure of HEWL, resulting in aggregation. Further studies are needed to investigate the mechanism of action and determine its potential side effects.

Insights into the remarkable attenuation of hen egg white lysozyme amyloid fibril formation mediated by biogenic gold nanoparticles stabilized by quercetin-functionalized tara gum

Aberrant protein misfolding and/or aggregation and fibrillation has been linked to the pathogenesis of several debilitating chronic diseases including Alzheimer's and Parkinson's disease. Inhibiting protein amyloidogenesis has been proposed as a viable strategy to prevent or ameliorate associated disorders. Herein, we investigated the anti-amyloidogenic properties of biogenic gold nanoparticles (QTG-GNP) prepared via a simple green chemistry route and stabilized by quercetin-functionalized tara gum (QTG). The synthesized QTG-GNP was extensively characterized for its physicochemical attributes via UV-visible spectroscopy, TEM, FESEM, EDX, DLS/Zeta potential, FTIR, RAMAN, XRD, XPS, and TGA analyses, as well as for its biological properties. The results revealed that small-sized (5.01 ± 1.17 nm), well-dispersed, highly stable and round-shaped biogenic gold nanoparticles were successfully synthesized at room temperature with QTG as the sole reductant /stabilizer. Importantly, QTG-GNP demonstrated potent anti-aggregation and fibrillation inhibitory effects against amyloidogenic hen egg white lysozyme (HEWL). Also, QTG-GNP was able to dissociate pre-formed HEWL amyloid fibrils. Furthermore, the constructed nanoparticles exhibited potent anti-radical activities against DPPH and ABTS⁺ and were cytocompatible with mouse L929 fibroblast cells. On the basis of these findings, it was established that QTG-GNP holds strong prospects for further development as an agent for countering protein aggregation and associated disease conditions.

Potential of tetradecyltrimethylammonium bromide in preventing fibrillation/aggregation of lysozyme: biophysical studies

A key step in the prevention of neurodegenerative disorders is to inhibit protein aggregation or fibrillation process. Functionality recognition is an essential strategy in developing effective therapeutics in addressing the treatment of amyloidosis. Here, we have focused on an approach based on structure-property energetics correlation associated with tetradecyltrimethylammonium bromide (TTAB), a cationic surfactant that acts as an inhibitor targeting different stages of hen egg-white lysozyme fibrillation. Characterization of amyloid fibrils and the inhibitory capability of 16 mM TTAB surfactant on fibrillation were investigated with the calorimetric, spectroscopic and microscopic techniques. ThT binding fluorescence studies inferred that micellar TTAB exerts its maximum inhibitory effect against amyloid fibrillation than monomer TTAB. The TEM measurements also confirmed complete absence of amyloid fibrils at micellar TTAB. At the same time, the transformation of β-sheet to α-helix under the action of TTAB was confirmed by the Far-UV CD spectroscopy. Although there have been some reports suggesting that cationic surfactants can induce aggregation in proteins, this work suggests that polar interactions between head groups of TTAB and amyloid fibrils are the predominant factors that cause retardation in fibrillation by interrupting/disturbing the intermolecular hydrogen bond of β-sheets. The present finding has explored the knowledge-based details in developing efficient potent inhibitors and provides a platform to treat diseases associated with protein misfolding.Communicated by Ramaswamy H. Sarma.

Role of salts and solvents on the defibrillation of food dye "sunset yellow" induced hen egg white lysozyme amyloid fibrils

Several food dyes are known to induce amyloid fibrillation when interacting with proteins. Here, we studied the role of sunset yellow (SY) in the amyloid fibrillation of hen egg white lysozyme (HEWL) and characterized the changes using spectroscopy techniques. Turbidity results showed that SY dye induces aggregation in HEWL in concentrations dependent manner. The aggregation induced by SY dye is kinetically very fast, no lag phase was detected, and the kinetics process follows an isodesmic kinetics pathway. The SY-dye induce aggregates have cross-β secondary structure confirmed by far-UV CD measurements. The effect of salts and solvents was also seen on SY-induced aggregates. Turbidity, far-UV CD, and kinetics results suggest that certain concentrations of NaCl and (NH₄)₂SO₄ solubilize the SY-induce amyloid fibrils, but (NH₄)₂SO₄ is more effective. Similarly, solvents are also solubilized the SY-induces HEWL amyloid fibrillation but the order of defibrillation is as follows: Isopropanol> ethanol > methanol which signified that isopropanol is more effective than other solvents. The salts and solvents data suggest that the electrostatic, as well as hydrophobic interaction, is responsible for SY-induced amyloid fibrillation. These conformational changes should be examined, more seriously for the purpose of food safety.

The intriguing dose-dependent effect of selected amphiphilic compounds on insulin amyloid aggregation: Focus on a cholesterol-based detergent, Chobimalt

The amyloidogenic self-assembly of many peptides and proteins largely depends on external conditions. Among amyloid-prone proteins, insulin attracts attention because of its physiological and therapeutic importance. In the present work, the amyloid aggregation of insulin is studied in the presence of cholesterol-based detergent, Chobimalt. The strategy to elucidate the Chobimalt-induced effect on insulin fibrillogenesis is based on performing the concentration- and time-dependent analysis using a combination of different experimental techniques, such as ThT fluorescence assay, CD, AFM, SANS, and SAXS. While at the lowest Chobimalt concentration (0.1 µM; insulin to Chobimalt molar ratio of 1:0.004) the formation of insulin fibrils was not affected, the gradual increase of Chobimalt concentration (up to 100 µM; molar ratio of 1:4) led to a significant increase in ThT fluorescence, and the maximal ThT fluorescence was 3-4-fold higher than the control insulin fibril's ThT fluorescence intensity. Kinetic studies confirm the dose-dependent experimental results. Depending on the concentration of Chobimalt, either (i) no effect is observed, or (ii) significantly, ∼10-times prolonged lag-phases accompanied by the substantial, ∼ 3-fold higher relative ThT fluorescence intensities at the steady-state phase are recorded. In addition, at certain concentrations of Chobimalt, changes in the elongation-phase are noticed. An increase in the Chobimalt concentrations also triggers the formation of insulin fibrils with sharply altered morphological appearance. The fibrils appear to be more flexible and wavy-like with a tendency to form circles. SANS and SAXS data also revealed the morphology changes of amyloid fibrils in the presence of Chobimalt. Amyloid aggregation requires the formation of unfolded intermediates, which subsequently generate amyloidogenic nuclei. We hypothesize that the different morphology of the formed insulin fibrils is the result of the gradual binding of Chobimalt to different binding sites on unfolded insulin. A similar explanation and the existence of such binding sites with different binding energies was shown previously for the nonionic detergent. Thus, the data also emphasize the importance of a protein partially-unfolded state which undergoes the process of fibrils formation; i.e., certain experimental conditions or the presence of additives may dramatically change not only kinetics but also the morphology of fibrillar aggregates.

Hydrophobicity Enhances the Formation of Protein-Stabilized Foams

Screening proteins for their potential use in foam applications is very laborious and time consuming. It would be beneficial if the foam properties could be predicted based on their molecular properties, but this is currently not possible. For protein-stabilized emulsions, a model was recently introduced to predict the emulsion properties from the protein molecular properties. Since the fundamental mechanisms for foam and emulsion formation are very similar, it is of interest to determine whether the link to molecular properties defined in that model is also applicable to foams. This study aims to link the exposed hydrophobicity with the foam ability and foam stability, using lysozyme variants with altered hydrophobicity, obtained from controlled heat treatment (77 °C for 0-120 min). To establish this link, the molecular characteristics, interfacial properties, and foam ability and stability (at different concentrations) were analysed. The increasing hydrophobicity resulted in an increased adsorption rate constant, and for concentrations in the protein-poor regime, the increasing hydrophobicity enhanced foam ability (i.e., interfacial area created). At higher relative exposed hydrophobicity (i.e., ~2-5 times higher than native lysozyme), the adsorption rate constant and foam ability became independent of hydrophobicity. The foam stability (i.e., foam collapse) was affected by the initial foam structure. In the protein-rich regime-with nearly identical foam structure-the hydrophobicity did not affect the foam stability. The link between exposed hydrophobicity and foam ability confirms the similarity between protein-stabilized foams and emulsions, and thereby indicates that the model proposed for emulsions can be used to predict foam properties in the future.

SDS modulates amyloid fibril formation and conformational change in succinyl-ConA at low pH

The anionic surfactant sodium dodecyl sulfate (SDS) is homologous to the cellular membrane lipids, and is known to stimulate amyloid fibrillation in several proteins. However, the mechanism by which SDS influences aggregation and structural changes in succinylated protein has not been determined. In this study, we observed the effects of variable SDS concentrations on succinyl-ConA aggregation at pH 3.5 and proposed a possible mechanism of SDS-induced succinyl-ConA aggregation. We used several biophysical techniques to identify the changes caused by SDS. Our results suggest that SDS stimulates succinyl-ConA aggregation in a concentration-dependent manner. From turbidity measurements, it was evident that a very low concentration (<0.1 mM) of SDS did not induce succinyl-ConA aggregation and proteins remained soluble. However, aggregations were observed at 0.1-2.5 mM SDS, which then dissipated at SDS concentrations above 2.5 mM. Far-UV CD results suggest that the β-sheet secondary structure of succinyl-ConA transformed into the cross-β-sheet structure in the presence of aggregating SDS concentrations. Notably, at SDS concentrations above 2.5 mM, the succinyl-ConA β-sheet transformed into an α-helical structure. The SDS-induced succinyl-ConA amyloid-like aggregates were confirmed by transmission electron microscopy (TEM). We propose that SDS modulates amyloid fibrillation in succinyl-ConA due to electrostatic and hydrophobic interactions and succinylation affects SDS-induced succinyl-ConA aggregation.

Tuning of silica nanoparticle-lysozyme protein complexes in the presence of the SDS surfactant

The structures of the complexes of anionic silica nanoparticle (size ∼ 16 nm)-lysozyme (cationic) protein, tuned by the addition of the anionic surfactant sodium dodecyl sulfate (SDS), have been investigated by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The unique advantage of contrast variation SANS has been used to probe the role of individual components in binary and ternary systems. The cationic lysozyme protein (at pH ∼ 7) adsorbs on the anionic silica nanoparticles and forms mass fractal aggregates due to the strong attractive interaction, whereas similarly charged SDS does not interact physically with silica nanoparticles. The presence of SDS, however, remarkably affects the nanoparticle-protein interactions via binding with the oppositely charged segments of lysozyme. In general, the SDS-lysozyme complexes possess a variety of structures (e.g., insoluble complexes of Ly(DS)₈, crystalline structure, or micelle-like structure) depending on the surfactant-to-protein molar ratio (S/P). In the ternary system (HS40-lysozyme-SDS), lysozyme preferentially binds with SDS, instead of directly to nanoparticles. At low S/Ps (0 ≤ S/P ≤ 10), the SDS concentration is not enough to fully neutralize the charge of lysozyme, leading to the formation of cationic SDS-lysozyme complex-mediated nanoparticle aggregation. The morphology of the nanoparticle-(lysozyme-SDS) complexes is also found to be mass fractal kind where the fractal dimension increases with increasing SDS concentration. At S/P > 10, there is sufficient SDS to fully neutralize the lysozyme in the absence of competing charges from the particle but it is at S/P = 50 before all lysozyme desorbs from the particle and binds completely to the overwhelming amount of SDS, creating an oppositely charged lysozyme-SDS complex, which is repelled from the particle.

Phytochemical thymoquinone prevents hemoglobin glycoxidation and protofibrils formation: A biophysical aspect

d-ribose, a reducing sugar, in diabetic hyperglycemia provokes non-enzymatic glycoxidation of hemoglobin (Hb), an abundant protein of red blood cells (RBCs). Different types of intermediates adduct formation occur during glycoxidation, such as advanced glycation end-products (AGEs) which lead to amyloid formation due to structural and conformational alterations in protein. Therefore, the study of these intermediate adducts plays a pivotal role to discern their relationship with diabetes mellitus and related disorders. Here, we investigated the interaction mechanism of d-ribose with Hb, and Hb prebound phytochemical thymoquinone (TQ). Our investigation reveals that the interaction of TQ with histidine residues of Hb interferes with the interaction of d-ribose with glycine residues at the glycation-site. Based on that, we had performed a time-based (21-days) in-vitro glycoxidation study at 37 °C to investigate the structural perturbation mechanism of Hb at different time-intervals in absence/presence of TQ. We found that prolonged glycoxidation induces amyloid formation in absence of TQ but in its presence, the process was prohibited. In summary, this study examined and characterized biophysically different intermediate-states of protein carrying glycoxidation-modification. Our findings suggested that TQ potentially affects interaction of d-ribose with Hb that prevents glycoxidation and protofibril formation, which establishes TQ as a potential therapeutic agent.

Sodium fusidate prevents protein aggregation of silk fibroin and offers new perspectives for human lens material disaggregation

Silk fibroin (SF) is a non-pathological amyloidogenic protein prone, in solution, to the formation of amyloid-like aggregated species, displaying similarities in fibrillation kinetics with pathological amyloids, as widely reported in the literature. We show here, on the basis of different biophysical approaches (turbidity, Congo Red assays, CD, DLS and fluorescence), that fusidic acid (FA), a well-known antibiotic, acts on SF as an anti-aggregating agent in a dose-dependent manner, being also able to revert SF aggregation. FA binds to SF inducing changes in the environment of SF aromatic residues. We further provide the proof of principle that FA, already approved as drug on humans and used in ophthalmic preparations, displays its anti-aggregation properties also on lens material derived from cataract surgery and is capable of reducing aggregation. Thus it is suggested that FA can be foreseen as a therapeutic treatment for cataract and other protein aggregation disorders.

Mechanisms of amyloid proteins aggregation and their inhibition by antibodies, small molecule inhibitors, nano-particles and nano-bodies

Protein misfolding and aggregation can be induced by a wide variety of factors, such as dominant disease-associated mutations, changes in the environmental conditions (pH, temperature, ionic strength, protein concentration, exposure to transition metal ions, exposure to toxins, posttranslational modifications including glycation, phosphorylation, and sulfation). Misfolded intermediates interact with similar intermediates and progressively form dimers, oligomers, protofibrils, and fibrils. In amyloidoses, fibrillar aggregates are deposited in the tissues either as intracellular inclusion or extracellular plaques (amyloid). When such proteinaceous deposit occurs in the neuronal cells, it initiates degeneration of neurons and consequently resulting in the manifestation of various neurodegenerative diseases. Several different types of molecules have been designed and tested both in vitro and in vivo to evaluate their anti-amyloidogenic efficacies. For instance, the native structure of a protein associated with amyloidosis could be stabilized by ligands, antibodies could be used to remove plaques, oligomer-specific antibody A11 could be used to remove oligomers, or prefibrillar aggregates could be removed by affibodies. Keeping the above views in mind, in this review we have discussed protein misfolding and aggregation, mechanisms of protein aggregation, factors responsible for aggregations, and strategies for aggregation inhibition.

Exploring the inhibitory effects of liquiritigenin against tau fibrillation and related neurotoxicity as a model of preventive care in Alzheimer's disease

Aggregation of tau protein into the form of insoluble amyloid fibrils is linked with Alzheimer's disease. The identification of potential small molecules that can inhibit tau protein from undergoing aggregation has received a great deal of interest, recently. In the present study, the possible inhibitory effects of liquiritigenin as a member of chiral flavanone family on tau amyloid fibrils formation and their resulting neurotoxicity were assessed by different biophysical and cellular assays. The inhibitory effect of the liquiritigenin against tau amyloid formation was investigated using thioflavin T (ThT) and 1-Anilino-8-naphthalene sulfonate (ANS) fluorescence spectroscopy, Congo red (CR) binding assays, transmission electron microscopy (TEM) analysis, and circular dichroism (CD) spectroscopy. Neurotoxicity assays were also performed against neuron-like cells (SH-SY5Y) using 3-(4,5-Dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) reduction, reactive oxygen species (ROS), catalase (CAT) and caspase-3 activity measurements. We found that liquiritigenin served as an efficient inhibitor of tau amyloid fibrils formation through prevention of structural transition in tau structure, exposure of hydrophobic patches and their associated neurotoxicity mediated by decrease in the production of ROS and caspase-3 activity and elevation of CAT activity. These data may finally find applications in the development of promising inhibitors against amyloid fibril formation and treatment of Alzheimer's disease.

Using amyloid autofluorescence as a biomarker for lysozyme aggregation inhibition

The assembly of proteins into amyloidogenic aggregates underlies the onset and symptoms of several pathologies, including Alzheimer's disease, Parkinson's disease and type II diabetes. Among the efforts for fighting these diseases, there is a great demand for developing novel, fast and reliable methods for in vitro screening of new drugs that may suppress or reverse amyloidogenesis. Recent studies unravelled a progressive increase in a blue autofluorescence upon amyloid formation originated from many different proteins, including the peptide amyloid-β, lysozyme or insulin. Herein, we propose a drug screening method using this property, avoiding the use of external probe dyes. We demonstrate that the inhibition of lysozyme amyloid formation by means of two known inhibitors, tartrazine and amaranth, can be monitored based on the autofluorescence of lysozyme amyloid aggregates. Our results show that amyloid luminescence is an intrinsic property that can be potentially applied in a screening assay, allowing the ranking of drug efficiency. The assays demonstrated here are fast to perform and suitable for scaling using microplate assays, configuring a new sensitive and economically feasible method.

Bioinformatics and experimental studies on the structural roles of a surface-exposed α-helix at the C-terminal domain of Chondroitinase ABC I

A series of single and double mutants generated on residues of a surfaced-exposed helix at the C-terminal domain of chondroitinase ABC I (cABC I) from proteus vulgaris. M886A, G887E, and their respective double mutant, MA/GE were inspired by the sequence of a similar helix segment in 30S ribosomal protein S1. Additionally, M889I, Q891K, and the corresponding double mutant, MI/QK, were made regarding the sequence of a similar helix in chondroitin lyase from Proteus mirabilis. Circular dichroism spectra in the far-UV region, demonstrate that the ordered structure of wild-type (WT), and double mutants are the same; however, the helicity of the ordered structures in MI/QK is higher than that of the WT enzyme. When compared with the single mutants, the double mutants showed higher activity, and that the activity of MI/QK is higher than that of the WT enzyme. Heat-induced denaturation experiments showed that the stability of the tertiary structure of double mutants at moderate temperatures is higher compared with the WT, and single mutants. It concluded that this helix can be considered as one of the hot spots region that can be more manipulated to obtain improved variants of cABC I.

Nanoclay based study on protein stability and aggregation and its implication in human health

Protein aggregation is the major cause of several acute amyloid diseases such as Parkinson's, Huntington's, Alzheimer's, Lysozyme Systemic amyloidosis, Diabetes-II etc. While these diseases have attracted much attention but the cure is still unavailable. In the present study, Human Serum Albumin (HSA) and Human Lysozyme (HL) were used as the model proteins to investigate their aggregations. Nanoclays are hydrous silicates found in clay fraction of soil and known as natural nanomaterials. They have long been used in several applications in health-related products. In the present paper, the different types of nanoclays (MMT K-10, MMT K-30, Halloysite, Bentonite) were used to inhibit the process of HSA and HL aggregation. Aggregation experiments were evaluated using several biophysical tools such as Turbidity measurements, Intrinsic fluorescence, 1-anilino-8-naphthalene sulfonate (ANS), Thioflavin T (Th T), congo red (CR) binding assays and Circular dichroism. Results demonstrated that all the nanoclays inhibit the DTT-induced aggregation. However, bentonite and MMT K-10 were progressively intense and potent as they slowed down nucleation stage which can be perceived using several biophysical techniques. Hence, nanoclays can be used as an artificial chaperone and might provide effective treatment against several protein aggregation related disorders.

Studies on the effect of a Fupenzi glycoprotein on the fibrillation of bovine serum albumin and its antioxidant activity

In this study, the effect of a glycoprotein obtained from Fupenzi (FPZ) (Rubus chingii Hu.) on the fibrillation of bovine serum album (BSA) was investigated by multi-spectroscopic methods and transmission electron microscopy. Moreover, the cytotoxicity of the glycoprotein and the effect of it on H₂O₂-induced cell viability were investigated by cell counting kit and β-galactosidase kit, respectively. The experimental results indicated that the glycoprotein showed very low toxicity to NRK-52E cells and could obviously delay cell senescence and improve cell viability. Moreover, the glycoprotein could effectively inhibit the formation of BSA fibrils and destroy the stability of preformed BSA fibrils in a concentration-dependent manner. Generally, antioxidant capacities are thought to be related to the anti-amyloidogenic activity of inhibitors; therefore, to reveal the inhibitory mechanism, the anti-oxidative property of the glycoprotein was examined by DPPH and ABTS assays. The results demonstrated that FPZ glycoprotein had a remarkable antioxidant activity and the IC₅₀ values of DPPH and ABTS were 0.249 mg mL^-1 and 0.092 mg mL^-1, respectively. This work suggested that the FPZ glycoprotein had the potential to be designed a new therapeutic agent for attenuating aging and preventing the age-related diseases.

Mesocellular Silica Foams (MCFs) with Tunable Pore Size as a Support for Lysozyme Immobilization: Adsorption Equilibrium and Kinetics, Biocomposite Properties

The effect of the porous structure of mesocellular silica foams (MCFs) on the lysozyme (LYS) adsorption capacity, as well as the rate, was studied to design the effective sorbent for potential applications as the carriers of biomolecules. The structural (N2 adsorption/desorption isotherms), textural (SEM, TEM), acid-base (potentiometric titration), adsorption properties, and thermal characteristics of the obtained lysozyme/silica composites were studied. The protein adsorption equilibrium and kinetics showed significant dependence on silica pore size. For instance, LYS adsorption uptake on MCF-6.4 support (pore diameter 6.4 nm) was about 0.29 g/g. The equilibrium loading amount of LYS on MCF-14.5 material (pore size 14.5 nm) increased to 0.55 g/g. However, when the pore diameter was larger than 14.5 nm, the LYS adsorption value systematically decreased with increasing pore size (e.g., for MCF-30.1 was only 0.27 g/g). The electrostatic attractive interactions between the positively charged lysozyme (at pH = 7.4) and the negatively charged silica played a significant role in the immobilization process. The differences in protein adsorption and surface morphology for the biocomposites of various pore sizes were found. The thermal behavior of the studied bio/systems was conducted by TG/DSC/FTIR/MS coupled method. It was found that the thermal degradation of lysozyme/silica composites was a double-stage process in the temperature range 165-420-830 °C.

Denaturant effect on amyloid fibrils: Declasterization, depolymerization, denaturation and reassembly

Accumulation of amyloid fibrils in organism accompanies many serious diseases, such as Alzheimer's and Parkinson's diseases, diabetes, prion diseases, etc. It is generally accepted that amyloids are highly resistant to degradation, which complicates their elimination in vivo and is one of the reasons for their pathogenicity. However, using a wide range of physicochemical approaches and specially elaborated method for the tested samples preparation by equilibrium microdialysis technique, it is proved that the stability of amyloids is greatly exaggerated. It turned out that amyloid fibrils formed from at least two amyloidogenic proteins, one of which is a model object for fibrils studying and the second is the cause of hemodialysis amyloidosis in an acute renal failure, are less stable than monomeric proteins. A mechanism of the degradation/reassembly of amyloid fibrils was proposed. It was shown that amyloid «seed» is a factor affecting not only the rate of the fibrils formation, but also their structure. Obtained results are a step towards identifying effects that can lead to degradation of amyloids and their clearance without adverse influence on the functionally active state of the protein or to change the structure and, as a result, the pathogenicity of these protein aggregates.

Methylglyoxal modification reduces the sensitivity of hen egg white lysozyme to stress-induced aggregation: Insight into the anti-amyloidogenic property of α-dicarbonyl compound

The reactive α-oxoaldehyde, methylglyoxal reacts with different proteins to form Advanced Glycation End Products (AGEs) through Maillard reaction. Its level increases significantly in diabetic condition. Here, we have investigated the effect of different concentrations of methylglyoxal (200-400 µM) on the monomeric protein, hen egg white lysozyme (HEWL) following incubation for 3 weeks. Reaction of methylglyoxal with HEWL induced considerable changes in tertiary structure of the protein, but no significant alteration in secondary structure, as evident from different spectroscopic and biophysical studies. Interestingly, methylglyoxal modification was found to enhance the thermal stability of the protein and reduce its sensitivity to stress-induced aggregation. Finally, peptide mass fingerprinting revealed modification of arginine (Arg-45, Arg-14, Arg-68 or Arg-72) and lysine (Lys-116) residues of the protein to AGE adducts, namely, hydroimidazolone, tetrahydropyrimidine, and carboxyethyllysine. Methylglyoxal-derived AGE adducts (MAGE) appear to be responsible for the observed changes in protein. As demonstrated in the present study, the findings may highlight a possible therapeutic potential of the α-oxoaldehyde against protein misfolding and conformational disorder.Communicated by Ramaswamy H. Sarma.

An insight into the inhibition of fibrillation process verses disaggregation of preformed fibrils of bovine serum albumin by isoprenaline hydrochloride

This study is based on the analysis of the recent trend of medication in neurodegenerative diseases. Due to the asymptomatic nature of the diseases, medication delays. Therefore, mechanism of medication assists in removal of the symptoms. Therefore, in order to find out remedy for complete prevention of the disease we have considered "inhibition verses disaggregation" study. Various biophysical techniques such as turbidity measurement (TM), Thioflavin T (ThT) binding assays, circular dichroism (CD), transmission electron microscopy (TEM) etc. has been performed. Isoprenaline hydrochloride (ISO) was a good candidate for inhibition and disaggregation of preformed fibrils of BSA. Therefore, it is concluded that inhibition of fibrillation process was more momentous, effective procedure in restricting the aggregation by stabilizing the native conformation of BSA than the removal of preformed amyloid fibrils under in vitro condition. Forwarding ahead, to understand the efficiency of the two processes under in vivo condition, this study can be applied on animal models so that we can look forward on human beings as well for the development of vaccines. This study is concerned about the applied aspect of research in future so that we can hope for prevention of the disease instead of only removal of the symptoms.

Conditions Governing Food Protein Amyloid Fibril Formation-Part I: Egg and Cereal Proteins

Conditions including heating mode, time, temperature, pH, moisture and protein concentration, shear, and the presence of alcohols, chaotropic/reducing agents, enzymes, and/or salt influence amyloid fibril (AF) formation as they can affect the accessibility of amino acid sequences prone to aggregate. As some conditions applied on model protein resemble conditions in food processing unit operations, we here hypothesize that food processing can lead to formation of protein AFs with a compact cross β-sheet structure. This paper reviews conditions and food constituents that affect amyloid fibrillation of egg and cereal proteins. While egg and cereal proteins often coexist in food products, their impact on each other's fibrillation remains unknown. Hen egg ovalbumin and lysozyme form AFs when subjected to moderate heating at acidic pH separately. AFs can also be formed at higher pH, especially in the presence of alcohols or chaotropic/reducing agents. Tryptic wheat gluten digests can form fibrillar structures at neutral pH and maize and rice proteins do so in aqueous ethanol or at acidic pH, respectively.

Aggregation of amylin: Spectroscopic investigation

Apart from its relevance to pathology, protein misfolding disease like Type-II Diabetes Mellitus, caused by amyloids of amylin protein has attracted more attention due to structural changes occurring during the aggregation process. We report extensive spectroscopy data of amylin during fibril formation through Raman, FTIR, CD, UV-vis absorption and photoluminescence (PL) spectroscopy. UV-vis and PL spectrum showed the sigmoidal growth of fibril with a lag time of ~2 days, which is consistent with earlier reported work using dynamic light scattering (DLS). Raman spectra revealed the formation of parallel and anti-parallel β-sheet from 0% to 20% with ageing (1st day to 21st day) at pH 6.5 ± 0.1. The results are corroborated by CD and FTIR data. These show the change in β-sheet by 23% at pH 6.5 ± 0.1, 26% at pH = 1.0 ± 0.1 and 30% at pH = 12 ± 0.1. It is also shown that the formation and conversion of other secondary structures into β-sheet is very sensitive towards the pH and ageing. The study may be used for the development of therapeutic strategies that could inhibit or even reverse the process of aggregation.

Detecting lysozyme unfolding via the fluorescence of lysozyme encapsulated gold nanoclusters

Protein misfolding plays a critical role in the manifestation of amyloidosis type diseases. Therefore, understanding protein unfolding and the ability to track protein unfolding in a dynamic manner are of considerable interest. Fluorescence-based techniques are powerful tools for gaining real-time information about the local environmental conditions of a probe on the nanoscale. Fluorescent gold nanoclusters (AuNCs) are a new type of fluorescent probes which are <2 nm in diameter, incredibly robust and offer highly sensitive, wavelength tuneable emission. Their small size minimises intrusion and makes AuNCs ideal for studying protein dynamics. Lysozyme has previously been used to encapsulate AuNCs. The unfolding dynamics of lysozyme under different environmental conditions have been well-studied and being an amyloid type protein makes lysozyme an ideal candidate for encapsulating AuNCs in order to test their sensitivity to protein unfolding. In this study, we tracked the fluorescence characteristics of AuNCs encapsulated in lysozyme while inducing protein unfolding using urea, sodium dodecyl sulphate (SDS) and elevated temperature and compared them to complimentary circular dichroism spectra. It is found that AuNC fluorescence emission is quenched upon induced protein unfolding either due to a decrease in Forster Resonance Energy Transfer (FRET) efficiency between tryptophan and AuNCs or solvent exposure of the AuNC. Fluorescence lifetime measurements confirmed quenching to be collisional via oxygen dissolved in a solution which increases as the AuNC was exposed to the solvent during unfolding. Moreover, the longer decay component τ₁ was observed to decrease as the protein unfolded, due to the increased collisional quenching. It is suggested that AuNC sensitivity to solvent exposure might be utilised in the future as a new approach to studying and possibly even detecting amyloidosis type diseases.

Gallic acid influence on bovine serum albumin thermal stability

A thermoanalytical approach reveals the dual action of GA on BSA thermal stability.