Thioflavin T as an amyloid dye: fibril quantification, optimal concentration and effect on aggregation

Tiny but mighty! N,N-dimethyl-4-(5-nitrothiophen-2-yl)aniline, a push-pull fluorescent dye for lipid droplet imaging

Lipid droplets (LDs) are ubiquitous cellular organelles with a neutral lipid core containing triacylglycerols and cholesteryl esters surrounded by phospholipids. Recent findings indicate that LDs are intricately linked to diseases, such as cancer and neurological disorders, in addition to their roles in cellular senescence and immune responses. Herein, we describe a simple yet robust push-pull molecule, N,N-dimethyl-4-(5-nitrothiophen-2-yl)aniline (NiTA), as a versatile LD fluorescent probe. NiTA showed an absorption spectrum with a substantial bathochromic shift and a fluorescence spectrum with excellent solvatochromism. Leveraging the remarkable photophysical features of NiTA, we stained LDs in major immune cells, including T and B cells, and macrophages, and monitored the changes in LDs under oxidative and starvation conditions. Furthermore, we demonstrated the applicability of NiTA for visualizing the organization of medaka fish (Oryzias latipes) embryos during development. We expect the small yet powerful NiTA to be utilized in various applications, including fluorescence mapping to observe LD numbers, morphology, and polarity changes in animals and cells.

Advancing Parkinson's diagnosis: seed amplification assay for α-synuclein detection in minimally invasive samples

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by tremor, rigidity, and bradykinesia, beginning with early loss of dopaminergic neurons in the ventrolateral substantia nigra and advancing to broader neurodegeneration in the midbrain. The clinical heterogeneity of PD and the lack of specific diagnostic tests present significant challenges, highlighting the need for reliable biomarkers for early diagnosis. Alpha-synuclein (α-Syn), a protein aggregating into Lewy bodies and neurites in PD patients, has emerged as a key biomarker due to its central role in PD pathophysiology and potential to reflect pathological processes. Additionally, α-Syn allows earlier differentiation between PD and other neurodegenerative disorders with similar symptoms. Currently, detection of α-Syn pathology in post-mortem brain tissue remains the primary means of achieving a conclusive diagnosis, often revealing significant misdiagnoses. Seed amplification assay (SAA), initially developed for prion diseases, has been adapted to detect α-Syn aggregates in cerebrospinal fluid, showing promise for early diagnosis. Recent studies have demonstrated that SAA can also detect α-Syn aggregates in peripheral samples collected via minimally invasive procedures, such as skin, olfactory mucosa, saliva, and blood. However, the lack of standardized protocols limits clinical application. Standardizing protocols is essential to improve assay reliability and enable accurate patient identification for emerging therapies. This review examines studies on SAA for detecting α-Syn aggregates in minimally invasive samples, focusing on sample collection, processing, and reaction conditions.

Designing Amyloid-Like Protein Aggregates from Microalgal Biomass

Our societal dependence on petrochemical-derived plastics has significant environmental ramifications, with about 80% of such plastics ending up as persistent waste. To this end, we investigate the extraction and purification of proteins from microalgae, specifically spirulina and chlorella, and their self-assembly into amyloid-like aggregates as building blocks toward the development of sustainable bioplastic materials. After self-assembly, spirulina proteins formed beta-sheet-rich structures with a typical (albeit short and worm-like) fibrillar morphology, while chlorella proteins predominantly aggregated into nonfibrillar, spherical/annular structures. Despite their morphological differences, both microalgal protein aggregates exhibited impressive stability across a wide pH range, persisting up to pH 11 before disaggregating at pH 12. In short, this work highlights the importance of biomass source, protein purity, and composition on the aggregation process of differing proteins. Given the high protein content and expanding industrial production of microalgae, spirulina and chlorella present an untapped resource for the development of sustainable bioplastics.

Interaction of Metal Ion Stabilized Oligomeric Dipeptide with Lipid Membrane: Concurrent Observations of Supported Lipid Membrane, Wetting, and Uptake

The interaction of biomolecules with cell membranes is crucial due to their important role in governing cellular function and membrane dynamics. However, most of the studies predominantly focus on the interaction of monomeric forms of biomolecules with lipid membranes, leaving the effects of cytotoxic oligomeric self-aggregates largely unexplored. In this study, we report that metal ion stabilized oligomeric intermediates of diphenylalanine cause wetting and uptake, induce coalescence, resulting in significant structural alterations of lipid membranes with varying surface charges. On the other hand, fibrillar morphology of diphenylalanine facilitates the formation of supported phospholipid membranes through liposome deformation. These insights open new research directions with profound implications for biomedicine and nanotechnology and help in fundamental biological understanding.

Probing a salt-induced conformational switch in β2-microglobulin under low pH conditions

Self-assembly of proteins and peptides into amyloid fibrils is an active field of research due to its connection with debilitating human ailments such as Parkinson's disease, dialysis-related amyloidosis (DRA), and type II diabetes. In most disease conditions, amyloid formation proceeds via distinct on-pathway conformers such as oligomers and protofibrils. However, the detailed mechanism by which monomers transform into different species and contribute to disease progression remains an area of intense research. Isolating and characterizing distinct conformers are pertinent to understanding disease initiation and progression. One such ailment is DRA, where an amyloidogenic protein, β2-microglobulin (β2m), undergoes a profound conformational switch to adopt an amyloid fold. β2m amyloids accumulate in tissues such as joints and kidneys, causing tissue damage and dysfunction. Soluble β2m oligomers are considered more toxic than amyloids due to impaired cellular processes, resulting in cell death. In the present study, we have identified and characterized three stages of β2m aggregation, namely, oligomers, protofibrils, and fibrils, while varying salt concentrations and agitation under low pH conditions. Our kinetic results indicate that β2m oligomers and protofibrils follow a nucleation-independent pathway, whereas amyloids are formed through the classical nucleation process. Further, we implemented microscopic techniques and biochemical assays to verify the formation and stability of distinct conformers. We believe these findings provide insights into the process of amyloid formation, which may help us to understand the initiation of the disease at an early stage.

Unraveling the Molecular Pathways of Protein Fibrillation under Thermal Acid Hydrolysis

Artificial amyloid fibrils formed by globular proteins under thermal acid hydrolysis have drawn extensive attention due to their exceptional mechanical properties and ability to form functional materials. However, the mechanisms underlying their formation, particularly the initiation of fibrillation under heat-induced acid hydrolysis, are not yet fully understood. By developing a general approach that integrates experiment and theory, the molecular pathways by which β-lactoglobulin (β-lg) monomers convert into artificial fibrils under heat-induced aggregation and acid hydrolysis at concentrations of 0.15-2% w/w are revealed. Despite all mature β-lg fibrils originating from heat-induced intermediate aggregates, most aggregates are inactive structures without forming fibrils. Only a minority of aggregates (active structures) convert into fibrils facilitated by heat-induced acid hydrolysis. Particularly, the peptides with largely consistent protein sequences, exhibiting small variations, are identified as the building blocks for fibril elongation throughout the fibrillation process. Moreover, secondary nucleation is inhibited during fibril formation. The results expand the theoretical framework for understanding amyloid formation induced by thermal acid hydrolysis, which paves the way for precise control of artificial amyloid formation.

Mass-Spectrometry-Based GEE Footprinting Characterizes Kinetic Mechanisms and Sites of Conformational Change in Amyloid β 1-42 Aggregation

Understanding the dynamics of Aβ aggregation is critical for elucidating Alzheimer's disease (AD) progression. This study extends our previous work on Aβ42 using fast photochemical oxidation of proteins (FPOP) and pulsed hydrogen-deuterium exchange and introduces mass spectrometry (MS)-based glycine ethyl ester (GEE) footprinting, combined with kinetic modeling, to characterize Aβ42 conformational changes and elucidate polymer populations along its aggregation pathways. We investigated Aβ42 conformational changes by analyzing three distinct peptide regions generated by Lys-N digestion, revealing three different views of the aggregation behaviors. The middle and C-terminal regions are identified as primary aggregation sites; in contrast, the N-terminal peptide exhibited only minor changes in GEE modification, supporting its limited involvement in intermolecular interactions during aggregation. Amino-acid-level analysis provided higher spatial resolution: D1 underwent relatively constant footprinting throughout aggregation, whereas E3/D7, E22, and D23 showed more substantial decreases in the level of modification, underscoring their critical roles in aggregation. By integrating these findings with kinetic modeling, we identified four predominant polymeric populations involved in Aβ1-42 aggregation. This study reports, for the first time, a stable, specific, and slow chemical footprinting approach to characterizing Aβ1-42 aggregation, offering new insights into Aβ1-42 polymerization dynamics and enhancing our understanding of its role in AD pathology. The solvent accessibility features of the six acidic amino acids and the C terminus calculated from the final, fibril state structure of Aβ42 are consistent with the footprinting results.

Coenzyme Q10 Enhances Resilience of Mitochondrial-like Membranes Against Amyloidogenic Peptides

Mitochondria possess a double-membrane envelope which is susceptible to insult by pathogenic intracellular aggregates of amyloid-forming peptides, such as the amyloid-beta (1-42) (Aβ42) peptide and the human islet amyloid polypeptide (hIAPP). The molecular composition of membranes plays a pivotal role in regulating peptide aggregation and cytotoxicity. Therefore, we hypothesized that modifying the physicochemical properties of mitochondrial model membranes with a small molecule might act as a countermeasure against the formation of, and damage by, membrane-active amyloid peptides. To investigate this, we inserted the natural ubiquinone Coenzyme Q10 (CoQ10) in model mito-mimetic lipid vesicles, and studied how they interacted with Aβ42 and hIAPP peptide monomers and oligomers. Our results demonstrate that the membrane incorporation of CoQ10 significantly attenuated fibrillization of the peptides, whilst also making the membranes more resilient against peptide-induced permeabilization. Furthermore, these protective effects were linked with the ability of CoQ10 to enhance membrane packing in the inner acyl chain region, which increased the mechanical stability of the vesicle membranes. Based on our collective observations, we propose that mitochondrial resilience against toxic biomolecules implicit in protein misfolding disorders such as Alzheimer's disease and type-2 diabetes, could potentially be enhanced by increasing CoQ10 levels within mitochondria.

A Direct Relationship Between 'Blood Stasis' and Fibrinaloid Microclots in Chronic, Inflammatory, and Vascular Diseases, and Some Traditional Natural Products Approaches to Treatment

'Blood stasis' (syndrome) (BSS) is a fundamental concept in Traditional Chinese Medicine (TCM), where it is known as Xue Yu (). Similar concepts exist in Traditional Korean Medicine ('Eohyul') and in Japanese Kampo medicine (Oketsu). Blood stasis is considered to underpin a large variety of inflammatory diseases, though an exact equivalent in Western systems medicine is yet to be described. Some time ago we discovered that blood can clot into an anomalous amyloid form, creating what we have referred to as fibrinaloid microclots. These microclots occur in a great many chronic, inflammatory diseases are comparatively resistant to fibrinolysis, and thus have the ability to block microcapillaries and hence lower oxygen transfer to tissues, with multiple pathological consequences. We here develop the idea that it is precisely the fibrinaloid microclots that relate to, and are largely mechanistically responsible for, the traditional concept of blood stasis (a term also used by Virchow). First, the diseases known to be associated with microclots are all associated with blood stasis. Secondly, by blocking red blood cell transport, fibrinaloid microclots provide a simple mechanistic explanation for the physical slowing down ('stasis') of blood flow. Thirdly, Chinese herbal medicine formulae proposed to treat these diseases, especially Xue Fu Zhu Yu and its derivatives, are known mechanistically to be anticoagulatory and anti-inflammatory, consistent with the idea that they are actually helping to lower the levels of fibrinaloid microclots, plausibly in part by blocking catalysis of the polymerization of fibrinogen into an amyloid form. We rehearse some of the known actions of the constituent herbs of Xue Fu Zhu Yu and specific bioactive molecules that they contain. Consequently, such herbal formulations (and some of their components), which are comparatively little known to Western science and medicine, would seem to offer the opportunity to provide novel, safe, and useful treatments for chronic inflammatory diseases that display fibrinaloid microclots, including Myalgic Encephalopathy/Chronic Fatigue Syndrome, long COVID, and even ischemic stroke.

An approach to characterize mechanisms of action of anti-amyloidogenic compounds in vitro and in situ

Amyloid aggregation is associated with neurodegenerative disease and its modulation is a focus of drug development. We developed a chemical proteomics pipeline to probe the mechanism of action of anti-amyloidogenic compounds. Our approach identifies putative interaction sites with high resolution, can probe compound interactions with specific target conformations and directly in cell and brain extracts, and identifies off-targets. We analysed interactions of six anti-amyloidogenic compounds and the amyloid binder Thioflavin T with different conformations of the Parkinson's disease protein α-Synuclein and tested specific compounds in cell or brain lysates. AC Immune compound 2 interacted with α-Synuclein in vitro, in intact neurons and in neuronal lysates, reduced neuronal α-Synuclein levels in a seeded model, and had protective effects. EGCG, Baicalein, ThT and doxycycline interacted with α-Synuclein in vitro but not substantially in cell lysates, with many additional putative targets, underscoring the importance of testing compounds in situ. Our pipeline will enable screening of compounds against any amyloidogenic proteins in cell and patient brain extracts and mechanistic studies of compound action.

Biomimetic Hydrogels from Mixed Gellan Gum and Tryptophan Zipper Self-Assembling Peptides

Peptide self-assembly has been used to fabricate synthetic hydrogels that emulate many of the chemical and physical properties of natural hydrogels. However, these materials often lack stability for many applications and do not display the native bioactivity found in tissue. Here we demonstrate a hybrid hydrogel system in which self-assembling peptides are integrated with polysaccharides to enhance gelation and provide improved mechanics and bioactivity. A peptide based on the tryptophan zipper (trpzip) motif was mixed with the anionic polysaccharide gellan gum, demonstrating gelation within minutes with increased stiffness compared to that of trpzip alone. The hybrid material maintained viscoelastic character with shear-thinning, self-healing, and stress-relaxation on the order of natural materials like collagen. All hydrogels supported cell adhesion and viability with increased gellan gum content, promoting cell assembly into aggregates. The enhanced gelation kinetics, stability, self-healing, and bioactivity of these materials make them promising candidates as matrices for cell culture and reagents for biofabrication and syringe extrusion for biological delivery.

Multimeric interacting interface of biologically synthesized zinc oxide nanoparticle corona efficiently sequesters α-synuclein against protein fibrillation

Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons along with the accumulation of amyloid plaques with alpha-synuclein (αS) as the major constituent. αS is an intrinsically disordered protein with the potential to undergo a cascade of structural transitions from a soluble disordered conformation to ordered cross-β-sheet-rich insoluble amyloid fibrils. Small molecules like polyphenols and peptides with anti-amyloidogenic potential can mitigate fibrillation in vitro but fail in vivo owing to poor bioavailability. To overcome this problem, a platform that simultaneously enhances the bioavailability of the mitigators and efficiently sequesters αS monomers against amyloidosis is needed. Accordingly, herein, the sequestering potential of surface-moderated zinc oxide nanoparticles was explored; in silico and in vitro studies showed that the moderated nano-interfaces efficiently sequestered αS in amorphous aggregates, which were termed as flocs. Moreover, GC-MS-based analysis of the bio-nano corona highlighted the rationale for efficient sequestering of αS monomers against amyloidosis by the biologically synthesized zinc oxide nanoparticle compared with other nanoparticle surfaces. Thus, this work exemplifies the multimeric interacting interface as a platform to efficiently sequester the αS protein and simultaneously enhance the bioavailability of the phytochemicals.

Delineating the Mechanistic Insight of Inhibition of α-Synuclein Fibrillation by Neuro Metabolite, Myo-inositol: Implications in Synucleopathies-Related Disorders

The fibrillation of α-synuclein (α-syn) is a major factor contributing to neuronal damage and is critical in developing synucleopathies-related disorders. Considering this, the discovery of new compounds that can inhibit or modulate α-syn aggregation is a significant area of research. While polyol osmolytes have been shown to reduce α-syn fibrillation, the impact of brain metabolites such as myo-inositol (MI) on α-syn aggregation has not yet been explored. This study is the first to examine the effects of MI on α-syn aggregation, utilizing spectroscopic, microscopic, and cell cytotoxicity assay. Various aggregation assays revealed that MI inhibits the α-syn fibrillation in a dose-dependent manner. Fluorescence microscopy observations suggest that MI inhibits the α-syn fibrillation by forming amorphous aggregates. MTT assay revealed that α-syn aggregates in the presence of different concentrations of MI were not toxic as compared to α-syn fibrils. Thus, the mechanistic insight of inhibition of α-syn fibrillation by MI was explored by employing interaction studies using spectroscopic, calorimetric, and in silico approaches. Surface plasmon resonance and isothermal titration calorimetry suggest that MI-α-syn interacted with significant binding affinity, and the reaction was spontaneous. Molecular docking results depict that MI interacted with the aggregation-prone residues (36-42) at the N-terminal of α-syn, thereby stabilizing the α-syn and preventing the fibril formation. Molecular dynamics simulation results demonstrate the stability of the complex formation of MI with α-syn. This study highlighted the mechanistic insight of MI on preventing the α-syn from forming amyloid fibril, which could be further explored for therapeutic management of synucleopathies-related disorders.

Rationally Designed Pentapeptide Analogs of Aβ19-23 Fragment as Potent Inhibitors of Aβ42 Aggregation

Amyloid beta (Aβ42 and Aβ40) aggregation, along with neurofibrillary tangles, is one of the major neurotoxic events responsible for the onset of Alzheimer's disease. Many potent peptide-based inhibitors mainly focusing on central hydrophobic core Aβ16-20 (KLVFF) have been reported in recent years. Herein, we report pentapeptides 1-4, based on the β-turn-inducing fragment Aβ19-23 (FFAED). The synthesis of peptides 1-4 was carried out using Fmoc/tBu-based solid-phase peptide synthesis technique, and it was found that pentapeptide 3 potently inhibit the aggregation propensity of Aβ42, when incubated with it at 37 °C for 48 h. The aggregation inhibition study was conducted using thioflavin T-based fluorescence assay and circular dichroism spectroscopy, and supported by transmission electron microscope imaging. The conformational change on the aggregation of Aβ42 and aggregation inhibition by peptides 1-4 was further evaluated using 1H-15N HSQC NMR spectroscopy. The results demonstrated that the most potent analog, peptide 3, effectively disrupts the aggregation process. This study is the first to demonstrate that an Aβ19-23 fragment mimic can disrupt the aggregation propensity of Aβ42.

MIPAR and ImageJ FIJI as Tools for Electron Microscopy Quantification of Amyloid Fibrils

Measuring of tau filaments is an important method that can provide useful information in the study of tau in vitro. However, methods such as right-angle laser light scattering and Thioflavin T fluorescence assay only provide bulk information on the amount of tau aggregation that is occurring. Electron microscopy (EM) can be used to provide a semiquantitative method on the lengths of individual filaments and provide a length distribution of tau aggregates. The issue with quantifying tau aggregation through EM is that it can be time costly if done manually. Here we explore two different programs, MIPAR and ImageJ FIJI, as methods to automate the quantification of EM grids. Using both programs to measure filaments produced from inducing 2N4R tau with the fatty acid arachidonic acid (ARA), we are able to reliably measure filaments producing similar results from MIPAR and ImageJ, with these methods applicable to other filamentous biological structures.

Ligands for Protein Fibrils of Amyloid-β, α-Synuclein, and Tau

Amyloid fibrils are characteristic features of many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. The use of small molecule ligands that bind to amyloid fibrils underpins both fundamental research aiming to better understand the pathology of neurodegenerative disease, and clinical research aiming to develop diagnostic tools for these diseases. To date, a large number of amyloid-binding ligands have been reported in the literature, predominantly targeting protein fibrils composed of amyloid-β (Aβ), tau, and α-synuclein (αSyn) fibrils. Fibrils formed by a particular protein can adopt a range of possible morphologies, but protein fibrils formed in vivo possess disease-specific morphologies, highlighting the need for morphology-specific amyloid-binding ligands. This review details the morphologies of Aβ, tau, and αSyn fibril polymorphs that have been reported as a result of structural work and describes a database of amyloid-binding ligands containing 4,288 binding measurements for 2,404 unique compounds targeting Aβ, tau, or αSyn fibrils.

Tuning the Dimensionality of Protein-Peptide Coassemblies to Build 2D Conductive Nanomaterials

The natural self-assembly tendency of proteins to build complex structural architectures has kindled inspiration in developing supramolecular structures through the rational design of biomacromolecules. While there has been significant progress in achieving precise control over the morphology of self-assembled structures, combining different molecules within assemblies enables the design of materials with increased complexity, sophisticated structures, and a broad spectrum of functionalities. Here, the development of 1D and 2D peptide-protein coassembled systems based on the design of amphiphilic peptides and engineered proteins is described. The peptide was optimized to form stable self-assembled fibers by evaluating, computationally and experimentally, the assembling tendencies and the supramolecular features of peptides with different lengths and negative charges. A superhelical repeat protein was engineered by fusing one or two amphiphilic peptides into one or both termini. This modification drove the coassembly between the self-assembled fibers and the protein with one or two peptides, resulting in 1D or 2D coassembled systems. The protein films and the 2D coassembled system exhibited high ionic conductivity for a biomolecular system, attributed to their high content of charged residues, positioning these materials as promising candidates for developing bioelectronic devices. Thus, this work provides a versatile framework for developing coassembled materials with tunable dimensionality by using biocompatible building blocks without any additional chemical moieties, highlighting the potential for their use in biocompatible electronics.

Assessing amyloid fibrils and amorphous aggregates: A review

Protein misfolding and aggregation play a central role in the progression of neurodegenerative diseases such as Alzheimer's and Parkinson's. These aggregates manifest either as structured amyloid fibrils enriched in β-sheet conformations or as irregular amorphous aggregates with diverse morphologies. Understanding their formation, structure, and behavior is critical for deciphering disease mechanisms and developing targeted diagnostics and therapeutics. This review presents an integrated overview of both conventional and advanced techniques used to detect, distinguish, and structurally characterize these protein aggregates. It covers a range of spectroscopic and spectrometric tools, such as fluorescence, Raman, and mass spectrometry that facilitate aggregate identification. Microscopy methods, including atomic force and electron microscopy, are highlighted for morphological analysis. The review also discusses in situ detection strategies using fluorescent dyes, conformation-specific antibodies, enzymatic reporters, and real-time imaging. Separation methods like centrifugation, electrophoresis, and chromatography are outlined alongside structural analysis tools such as X-ray diffraction. Furthermore, the growing utility of computational approaches and artificial intelligence in predicting aggregation propensities and integrating biological data is emphasized. By critically evaluating each method's capabilities and limitations, this review provides a practical and forward-looking resource for researchers studying the complex landscape of protein aggregation.

Enzyme-Instructed Self-Assembly Reprograms Fatty Acid Metabolism for Cancer Therapeutics

Enzyme-instructed self-assembly (EISA) is actively explored as a promising therapeutic approach for cancer treatment. However, the metabolic response of cancer cells to EISA remains under-studied. Here, by stimulated Raman scattering (SRS) imaging in C─H, fingerprint, and silent windows, it is found that the formation of peptide assemblies within and around cancer cells significantly enhances both lipids catabolism and fatty acids (FAs) uptake. It is further found that the increased uptake of FAs aids the resistance of cancer cells under EISA treatment, likely to cope with the stress induced by the peptide assemblies. Combining EISA with FAs uptake inhibition leads to enhanced cancer suppression compared to EISA alone, while additional FAs supplementation rescue cancer cells from EISA treatment, both in vitro and in 3D-culture spheroid models. These findings shed new light on the impact of EISA on the metabolic activities of cancer cells and suggest a new approach for improved cancer therapy.

Convergent Assembly of Homo- and Heterotypic Ubiquitin Chains from Functionalized, Expressed Monomers via Thiol-Ene Chemistry

Nature constructs ubiquitin tags with high spatiotemporal precision to execute defined functions that critically rely on the exact molecular composition of the ubiquitin chain. Deciphering the complex ubiquitin code is of paramount interest in biology and requires flexible access to homogeneous ubiquitin tags. As enzymatic approaches suffer from inherent drawbacks such as hardly controllable chain length or connectivity and substrate-specificity, we apply a combination of expression and chemical tools to assemble ubiquitin chains. Our strategy includes expression of ubiquitin-intein fusion constructs to obtain large quantities of defined ubiquitin monomers with C-terminal modifications such as hydrazides and propargylamides. Linkages between ubiquitins are generated via photoinitiated thiol-ene click (TEC) chemistry, resulting in a nearly native isopeptide bond. We demonstrate the generation of homo- and heterotypic ubiquitin oligomers with K27, 29, 48, and 63 linkages up to a K48-linked tetramer. The presented toolbox allows selective installation of ubiquitin on target peptides and proteins with reactive cysteine residues as demonstrated for segments of the microtubule-associated protein tau. Such segments can be implemented into protein semisyntheses as shown here for ubiquitylated full-length Tau4. The presented work combines minimal synthetic effort with high fidelity linkage chemistry, paving the way toward homogeneously ubiquitylated proteins.

Self-Assembled Short Peptide Amphiphile-Gold Nanostructures: A Novel Approach for Bacterial Infection Treatment

This study presents a simple and effective strategy for synthesizing biocompatible hybrid nanostructures composed of short peptide amphiphiles (sPA) and gold nanoparticles (AuNPs) for bacterial infection control. The self-assembling sPA molecules form stable β-sheet structures, which are further enhanced upon the addition of gold ions (Au(III)) and brief sunlight exposure, leading to the formation of functional AuNP-sPA nanostructures. Comprehensive spectroscopic and microscopic characterization confirms the successful integration of AuNPs with sPA, resulting in stable nanomaterials with potent antibacterial properties. The AuNP-sPA conjugates exhibit superior antibacterial activity against Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa with a high bacterial selectivity and biocompatibility with minimal cytotoxicity, reinforcing their therapeutic potential. These findings highlight AuNP-sPA nanostructures as promising alternatives to conventional antibiotics for targeted bacterial infection treatment.

Thioflavin T Inspirations: On the Photophysical and Aggregation Properties of Fluorescent Difluoroborates Based on the Benzothiazole Core

In this work, we investigated a novel series of fluorescent dyes based on benzothiazole core substituted with a palette of donor groups that differ in size, shape, and character (alkyl vs aromatic). These dyes exhibit an intramolecular charge transfer state in their electronic structure. The photophysical properties of the newly synthesized dyes were studied with an eye toward aggregation effects in solvents and mixtures of solvents differing in polarity. Moreover, multiphoton absorption studies were performed to determine the potential of the dyes in two-photon microscopy. The results of spectroscopic measurements were supported by electronic structure calculations using coupled-cluster theory. Overall, the results provide an indication regarding the optimal substituents to achieve bright emission in various media and how these properties are related to aggregation effects.

Dynamic Properties of β-Casein Fibril Adsorption Layers at the Air-Water Interface

Although the formation of the layers of fibrillar aggregates at liquid-liquid and liquid-gas interfaces can significantly increase the stability of disperse systems, like foams and emulsions, any information on their structure and properties is rather limited. In the present work, surface properties of the adsorption layers of fibrils of intrinsically disordered β-casein are investigated. For unpurified dispersions of the fibrils of this protein, the dynamic surface elasticity proved to be close to the values for the native protein solutions. This behavior is typical for dispersions of fibrils of globular proteins. However, previously studied fibrils of another intrinsically disordered protein, κ-casein, do not demonstrate this similarity. The contribution of β-casein fibrils to the dynamic surface properties becomes noticeable only after the purification of the dispersions from impurities of high surface activity. The dynamic surface elasticity increases up to 48 mN/m after two purification cycles, i.e., to values 4 times higher than the steady-state values of native protein adsorption layers at the same protein bulk concentrations.

Synthetic Strategy to Build High-Molecular-Weight Poly(L-tyrosine) and Its Unexplored β-Sheet Block Copolymer Nanoarchitectures

Synthesis of high-molecular-weight polypeptides and their block copolymer macromolecular architectures from β-sheet-promoting L-amino acids is still an unresolved problem. Here, an elegant steric hindrance-assisted ring-opening polymerization (SHAROP) strategy is introduced to access β-sheet poly(L-tyrosine) having more than 250 units. The scope of the synthetic methodology is expanded to access unexplored poly(L-tyrosine)-based higher-order β-sheet block copolymer nanoassemblies. In this strategy, a tert-butyl benzyl unit is employed as a steric handle that imbibes the solubility by promoting the α-helical conformation in the propagating polypeptide chains. The living ROP process enables the synthesis of well-defined block copolymers initiated by poly(L-tyrosine) living-chain ends or growing the poly(L-tyrosine) chains from the pre-existing macroinitiators of poly(L-glutamate) or poly(L-lysine). Acid-catalyzed postpolymerization deprotection restores the poly(L-tyrosine) blocks in their nascent β-sheet conformations. Thioflavin-T fluorescence assay establishes the β-sheet core-shell structures of these nanoassemblies, which are found to be nontoxic to mammalian cell lines.

Polyoxometalates as effective inhibitors of insulin amyloid fibrils: a promising therapeutic avenue

Insulin is listed on the WHO model list of essential medicines for a basic healthcare system. Due to its usage at regular intervals on diabetic patients, a disease condition called injection amyloidosis exists due to the propensity of insulin to form fibrils. Hence, it is essential to understand the aggregation of the protein insulin and understand the role of fibrillation of the protein insulin and possible inhibition. In this particular investigation, insulin fibrils were produced in a controlled environment. The study focused on exploring the potential of a special class of inorganic nanomaterials known as polyoxometalates (POMs) to inhibit the formation of these insulin amyloid fibrils. Four specific POMs-phosphomolybdic acid (PMA), silicomolybdic acid (SMA), tungstosilicic acid (TSA), and phosphotungstic acid (PTA)-were selected for assessing the inhibition of fibril formation by POMs using the Thioflavin T (ThT) assay. The molecular docking study also shows the binding sites of POMs with insulin. The results provided promising insights into the inhibitory effects of POMs on insulin amyloid fibrils. This investigation opens up potential avenues for exploring the application of Keggin POMs in the context of neurodegeneration.

Mechanistic Insights into the Neuroprotective Potential of Aegle marmelos (L.) Correa Fruits against Aβ-Induced Cell Toxicity in Human Neuroblastoma SH-SY5Y Cells

Background/Objectives: Amyloid-β (Aβ) plaque accumulation, oxidative stress, and cholinergic dysfunction are hallmarks of Alzheimer's disease (AD), a neurodegenerative disability that progresses over time, ultimately resulting in the loss of neurons. The side effects and limitations of current synthetic drugs have shifted attention toward natural alternatives. This study investigates the ethanolic extract of Aegle marmelos (L.) Corrêa fruits for their antioxidant, AChE-inhibitory, and anti-amyloidogenic properties, as well as their neuroprotective effects against amyloid beta-peptide (Aβ1-42). Methods: Phytochemical constituents were identified through HR-LCMS analysis and their antioxidant (DPPH, FRAP) and neuroprotective activities (AChE inhibition, ThT binding, MTT assay, ROS reduction, MMP restoration, and AD-related gene expression via qRT-PCR) were assessed using SHSY-5Y neuroblastoma cells. Results: The extract revealed the existence of flavonoids, phenols, and other bioactive substances. In vitro assays demonstrated strong antioxidant and AChE-inhibitory activities, while the ThT binding assay showed protection against amyloid-β aggregation. The extract exhibited no cytotoxicity in SHSY-5Y cells, even at a concentration of 500 μg/mL, whereas Aβ1-42 at 20 μM induced significant cytotoxicity. Co-treatment with Aβ1-42 (10 μM and 20 μM) and the extract improved cell viability (˃50%) and reduced ROS levels. Additionally, the extract restored mitochondrial membrane potential in Aβ1-42 treated cells, highlighting its role in preserving mitochondrial function. Conclusions: These findings suggest that A. marmelos fruits serve as a powerful source of natural antioxidants, AChE inhibitors, and anti-amyloidogenic agents, positioning them as a compelling option for AD treatment.

Disruption of fibrillar assemblies of L-phenylalanine using polyphenol-passivated nanocarbon as a potential therapeutic strategy against phenylketonuria

One of the pathological manifestations of phenylketonuria (PKU) is the formation of fibrillar assemblies of the aromatic amino acid L-phenylalanine at pathological concentrations. As a possible therapeutic strategy for PKU, we introduce a nanocarbon system passivated with polyphenol gallic acid (CNPGA), which has the ability to disrupt and inhibit the formation of fibrillar assemblies. The CNPGA was prepared using a rapid and facile microwave-assisted one-pot method from an aqueous solution of sucrose and gallic acid and fully characterized using UV-Vis, FT-IR, XRD, XPS, TEM, zeta potential and DLS measurements. The CNPGA-mediated inhibition and disruption of L-phenylalanine fibrils was examined using a thioflavin T (ThT) assay. The change in the conformation of the fibrils upon CNPGA treatment was assessed by means of circular dichroism spectroscopy. Visual analysis of the rupture of fibrillar assemblies was performed using SEM. Finally, the biocompatibility of CNPGA was evaluated in two normal cell lines, HaCaT (human epidermal keratinocyte cell line) and Vero (African green monkey kidney cell line) cells.

Transition-State-Dependent Spontaneous Generation of Reactive Oxygen Species by Aβ Assemblies Encodes a Self-Regulated Positive Feedback Loop for Aggregate Formation

Amyloid-β (Aβ) peptides exhibit distinct biological activities across multiple physical length scales, including monomers, oligomers, and fibrils. The transition from Aβ monomers to pathological aggregates correlates with the emergence of chemical toxicity, which plays a critical role in the progression of neurodegenerative disorders. However, the relationship between the physical state of Aβ assemblies and their chemical toxicity remains poorly understood. Here, we show that Aβ assemblies can spontaneously generate reactive oxygen species (ROS) through transition-state-specific inherent nonenzymatic redox activity. During the transition from initial monomers to intermediate oligomers or condensates to final fibrils, interfacial electrochemical environments emerge and vary at the liquid-liquid and liquid-solid interfaces. Determined by the vibrational Stark effect using electronic pre-resonance stimulated Raman scattering microscopy, the interfacial field of such assemblies is on the order of 10 MV/cm. Interfacial activity, which depends on the Aβ transition state, can modulate the spontaneous oxidation of hydroxide anions, which leads to the formation of hydroxyl radicals. Interestingly, this redox activity modifies the chemical composition of Aβ and establishes a self-regulated positive feedback loop that accelerates aggregation and promotes fibril formation, which represents a new functioning mechanism of Aβ aggregation beyond physical cross-linking. Leveraging this mechanistic insight, we identified small molecules capable of disrupting the feedback loop by scavenging hydroxyl radicals or perturbing the interface, thereby inhibiting fibril formation. Our findings provide a nonenzymatic model of neurotoxicity and reveal the critical role of physical interfaces in modulating the chemical dynamics of biomolecular assemblies. These results offer a novel framework for therapeutic intervention in Alzheimer's disease and related neurodegenerative disorders.

Advance in peptide-based drug development: delivery platforms, therapeutics and vaccines

The successful approval of peptide-based drugs can be attributed to a collaborative effort across multiple disciplines. The integration of novel drug design and synthesis techniques, display library technology, delivery systems, bioengineering advancements, and artificial intelligence have significantly expedited the development of groundbreaking peptide-based drugs, effectively addressing the obstacles associated with their character, such as the rapid clearance and degradation, necessitating subcutaneous injection leading to increasing patient discomfort, and ultimately advancing translational research efforts. Peptides are presently employed in the management and diagnosis of a diverse array of medical conditions, such as diabetes mellitus, weight loss, oncology, and rare diseases, and are additionally garnering interest in facilitating targeted drug delivery platforms and the advancement of peptide-based vaccines. This paper provides an overview of the present market and clinical trial progress of peptide-based therapeutics, delivery platforms, and vaccines. It examines the key areas of research in peptide-based drug development through a literature analysis and emphasizes the structural modification principles of peptide-based drugs, as well as the recent advancements in screening, design, and delivery technologies. The accelerated advancement in the development of novel peptide-based therapeutics, including peptide-drug complexes, new peptide-based vaccines, and innovative peptide-based diagnostic reagents, has the potential to promote the era of precise customization of disease therapeutic schedule.

Hydrophobic interaction of glycitein and α-synuclein inhibits the protein aggregation: A future perspective for modulation of Parkinson's disease

Despite the worldwide prevalence of Parkinson's disease (PD), there are currently no effective methods for treating or preventing α-synucleinopathy. Research has demonstrated that small molecules are capable of preventing α-synuclein aggregation and the associated neurotoxicity. Nonetheless, the specific anti-amyloid mechanism of these compounds is not thoroughly comprehended in detail. In this study, the interaction between glycitein and α-synuclein was evaluated. Furthermore, the aggregation of α-synuclein in the presence of glycitein was examined utilizing several arrays. Thermodynamic results indicated that glycitein, an O-methylated isoflavone, binds to α-synuclein by creating a static complex, wherein non-covalent interactions, especially hydrophobic forces, served as the primary intermolecular forces stabilizing the complex. We further found that glycitein serves as a promising bioactive agent against α-synuclein amyloid fibrillation in a concentration-dependent fashion, modulating the formation of hydrophobic regions, the solution's surface tension, and the shift from natural random coil to β-sheet configurations, in addition to potential interactions with α-synuclein monomers and amyloid fibril formations. Moreover, we noted that glycitein prevents the neurotoxicity caused by α-synuclein aggregates by shielding PC12 cells from ROS production and caspase-3 activation. These results emphasize the significance of using bioactive small compounds for the prevention and treatment of PD.

Mesoscopic p53-rich clusters represent a new class of protein condensates

The protein p53 is an important tumor suppressor, which transforms, after mutation, into a potent cancer promotor. Both mutant and wild-type p53 form amyloid fibrils, and fibrillization is considered one of the pathways of the mutants' oncogenicity. p53 incorporates structured domains, essential to its function, and extensive disordered regions. Here, we address the roles of the ordered (where the vast majority of oncogenic mutations localize) and disordered (implicated in aggregation and condensation of numerous other proteins) domains in p53 aggregation. We show that in the cytosol of model breast cancer cells, the mutant p53 R248Q reproducibly forms fluid aggregates with narrow size distribution centered at approximately 40 nm. Similar aggregates were observed in experiments with purified p53 R248Q, which identified the aggregates as mesoscopic protein-rich clusters, a unique protein condensate. Direct TEM imaging demonstrates that the mesoscopic clusters host and facilitate the nucleation of amyloid fibrils. We show that in solutions of stand-alone ordered domain of WT p53 clusters form and support fibril nucleation, whereas the disordered N-terminus domain forms common dense liquid and no fibrils. These results highlight two unique features of the mesoscopic protein-rich clusters: their role in amyloid fibrillization that may have implications for the oncogenicity of p53 mutants and the defining role of the ordered protein domains in their formation. In a broader context, these findings demonstrate that mutations in the DBD domain, which underlie the loss of cancer-protective transcription function, are also responsible for fibrillization and, thus, the gain of oncogenic function of p53 mutants.

Schiff Base-platinum and ruthenium complexes and anti-Alzheimer properties

This study investigates the effects of Pt and Ru complexes containing a Schiff base with a diimine structure on Alzheimer's disease. The Schiff base (N1E,N2E)-N1,N2-bis(isoquinolin-4-ylmethylene)benzene-1,2-diamine (I) and the novel Pt(II) and Ru(II) complexes (Ia and Ib) were synthesized and characterized using FTIR, NMR (1H, 13C), mass spectrometry, and elemental analyses. Their ability to inhibit amyloid beta (Aβ1-42) aggregation was determined in vitro using the SH-SY5Y cell line. Fluorescence spectroscopy investigated the early aggregation kinetics and dose-dependent characteristics of Aβ1-42 with the complexes. Transmission electron microscopy confirmed the results. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 1H NMR spectroscopy examined the interaction with Aβ1-16. Electrochemical analysis using square wave voltammetry monitored the interaction with Aβ1-42. The synthesized complexes were active in inhibiting amyloid aggregation at a low molar ratio.

Mesoscale orchestration of collagen-based hierarchical mineralization

Mesoscale building blocks are instrumental in bridging multilevel hierarchical mineralization, endowing macroscale entities with remarkable functionality and mechanical properties. However, the mechanism orchestrating the homogeneous morphology of mesoscale mineralized motifs in collagen-based hard tissues remains unknown. Here, utilizing avian tendons as a mineralization model, we reveal a robust correlation between the mesoscale mineralized spherules and the presence of phosvitin. By designing a phosvitin-stabilized biomineral cluster medium, we replicate the well-defined mesoscale spherical structure within collagen matrix in vitro and ex vivo. In-depth studies reveal that phosvitin undergoes a conformational transition in the presence of biominerals at physiological concentrations, and self-assembles into mineral-dense amyloid-like aggregates. The spatial binding of these mineral-dense aggregates to collagen serves as a template for guiding the formation of mineralized spherules on the mesoscale. On the nanoscale, this binding facilitates mineral precursor release and diffusion into the fibrils for intrafibrillar mineralization. This discovery underscores the pivotal role of phosvitin-biomineral aggregates in templating hierarchical mineralization from the mesoscale to the nanoscale. This study not only elucidates the intricate mechanism underlying the collagen-based mineralization hierarchy but also promotes a cutting-edge advance in highly biomimetic material design and regenerative medicine.

Thiocyanate Ion (SCN-) Offers a Major Impact in Rapid Protein Amyloidosis: A Salient Role Played by Protein Solvation

Thiocyanate (SCN-) is known to be a naive ion abundant in biological fluids, blood, and urine. It is also used as a biomarker, as it can penetrate to the brain by crossing the blood brain barrier (BBB) and also gets into the cerebrospinal fluid (CSF) through the blood-CSF barrier. Considering its importance in human physiology, we examine the effect of SCN- ions on three model proteins: ovalbumin (Ova), bovine serum albumin (BSA), and lysozyme (Lys). We observe that an elevated level of SCN- (∼0.5 M) leads to an otherwise unusual instant fibrilization of all these proteins at pH 2 at ambient temperature. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) reveal two distinct initial amyloid-aggregated states: nucleus, protofibril, and two mature fibril states (upon 24 h of incubation): cross-linked network or matrix and bundle-like structures. Despite the structural variation of the three proteins, the formation of these morphologies depends on the counterion: Na+ and guanidinium (Gdm+). Since these processes are assisted by the associated alteration in protein hydration, we determine individual protein and salt hydration at the thus-obtained different phases using THz-FTIR spectroscopy in the 1.5-22.5 THz (50-750 cm-1) frequency window. We found that, depending on the counterion, interfacial hydration could act either as a "lubricant" or as a "de-wetting" agent, and the findings can be a potential foundation for future handling of amyloidosis.

Distinct Aggregation Behavior of N-Terminally Truncated Aβ4-42 Over Aβ1-42 in the Presence of Zn(II)

The deposition of amyloid-β (Aβ) aggregates and metal ions within senile plaques is a hallmark of Alzheimer's disease (AD). Among the modifications observed in Aβ peptides, N-terminal truncation at Phe4, yielding Aβ4-x, is highly prevalent in AD-affected brains and significantly alters Aβ's metal-binding and aggregation profiles. Despite the abundance of Zn(II) in senile plaques, its impact on the aggregation and toxicity of Aβ4-x remains unexplored. Here, we report the distinct aggregation behavior of N-terminally truncated Aβ, specifically Aβ4-42, in the absence and presence of either Zn(II), Aβ seeds, or both, and compare it to that of full-length Aβ1-42. Our findings reveal notable differences in the aggregation profiles of Aβ4-42 and Aβ1-42, largely influenced by their different Zn(II)-binding properties. These results provide insights into the mechanisms underlying the distinct aggregation behavior of truncated and full-length Aβ in the presence of Zn(II), contributing to a deeper understanding of AD pathology.

Molecular Rotors Detect the Formation and Conversion of α-Synuclein Oligomers

α-Synuclein is an intrinsically disordered protein that forms amyloids in Parkinson's disease. Currently, detection methods predominantly report on the formation of mature amyloids but are weakly sensitive to the early stage, toxic oligomers. Molecular rotors are fluorophores that sense changes in the viscosity of their local environment. Here, we monitor α-synuclein oligomer formation using the fluorescence lifetime of molecular rotors. We detect oligomer formation and conversion into amyloids for wild-type and two α-synuclein variants, the pathological mutant A30P and ΔP1 α-synuclein, which lacks a master regulator region of aggregation (residues 36-42). We report that A30P α-synuclein shows a rate of oligomer formation similar to that of wild-type α-synuclein, whereas ΔP1 α-synuclein shows delayed oligomer formation. Additionally, both variants demonstrate a slower conversion of oligomers into amyloids. Our method provides a quantitative approach to unveiling the complex mechanism of α-synuclein aggregation, which is key to understanding the pathology of Parkinson's disease.

Newer Therapeutic Approaches in Treating Alzheimer's Disease: A Comprehensive Review

Alzheimer's disease (AD) is an aging-related irreversible neurodegenerative disease affecting mostly the elderly population. The main pathological features of AD are the extracellular Aβ plaques generated by APP cleavage through the amyloidogenic pathway, the intracellular neurofibrillary tangles (NFT) resulting from the hyperphosphorylated tau proteins, and cholinergic neurodegeneration. However, the actual causes of AD are unknown, but several studies suggest hereditary mutations in PSEN1 and -2, APOE4, APP, and the TAU genes are the major perpetrators. In order to understand the etiology and pathogenesis of AD, various hypotheses are proposed. These include the following hypotheses: amyloid accumulation, tauopathy, inflammation, oxidative stress, mitochondrial dysfunction, glutamate/excitotoxicity, cholinergic deficiency, and gut dysbiosis. Currently approved therapeutic interventions are donepezil, galantamine, and rivastigmine, which are cholinesterase inhibitors (ChEIs), and memantine, which is an N-methyl-d-aspartate (NMDA) antagonist. These treatment strategies focus on only symptomatic management of AD by attenuating symptoms but not regeneration of neurons or clearance of Aβ plaques and hyperphosphorylated Tau. This review focuses on the pathophysiology, novel therapeutic targets, and disease-altering treatments such as α-secretase modulators, active immunotherapy, passive immunotherapy, natural antioxidant products, nanomaterials, antiamyloid therapy, tau aggregation inhibitors, transplantation of fecal microbiota or stem cells, and microtubule stabilizers that are in clinical trials or still under investigation.

Electroconductive Bionanocomposites from Black Soldier Fly Proteins for Green Flexible Electronics

Printed and flexible electronics hold the potential to revolutionize the world of electronic devices. A primary focus today is their circularity, which can be achieved by using biobased materials. In this study, electrically conductive bionanocomposite materials suitable for flexible electronics were fabricated using proteins from the black soldier fly (BSF, Hermetia illucens). The valorization of BSF biomacromolecules is currently being pursued in the framework of emerging circular economy models for the bioconversion of the Organic Fraction of Municipal Solid Waste (OFMSW), where BSF has been demonstrated to act as an extremely efficient bioconverter to provide lipids, chitin, and proteins. Here, the BSF protein extracts were characterized by proteomic techniques, revealing a pool of myofibrillar proteins able to interact through intermolecular β-sheet interactions. Flexible and electroconductive bionanocomposite materials were next formulated by combining BSF proteins with a conductive carbon black (CCB), either in its pristine form or functionalized with 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP), using water as the only solvent and incorporating glycerol and carboxymethylcellulose (CMC) as additional green ingredients. A sustainable, low-pressure cold plasma (LPCP) technology was ultimately proposed to achieve high film surface hydrophobicity. Characterized by effective biodegradability, strain-sensing properties, high electrical conductivity (up to 0.9 × 10-2 S/cm at a filler content of 8% v/v (15% w/w)), and high surface hydrophobicity, the bionanocomposites presented here may be well suited for disposable flexible electronics, as in wearable devices, electrostatic discharge fabrics, or packaging, hence offering new routes toward OFMSW valorization and the development of green flexible electronics.

Cathepsin B prevents cell death by fragmentation and destruction of pathological amyloid fibrils

Amyloid fibrils cause organ and tissue dysfunction in numerous severe diseases. Despite the prevalence and severity of amyloidoses, there is still no effective and safe anti-amyloid therapy. This study investigates the impact of cysteine protease cathepsin B (CTSB) on amyloids associated with Alzheimer's and Parkinson's diseases, hemodialysis, and lysozyme amyloidosis. We analyzed the effect of CTSB on the size, structure, and proteotoxicity of amyloid fibrils formed from alpha-synuclein, abeta peptide (1-42), insulin, and lysozyme using a combination of spectroscopic, microscopic, electrophoretic, and colorimetric methods. Our comprehensive research revealed a dual effect of CTSB on amyloid fibrils. Firstly, CTSB induced amyloid fragmentation while preserving their ordered morphology, and, secondly, it "loosened" the tertiary structure of amyloids and reduced the regularity of the secondary structure. This dual mechanism of action was universal across fibrils associated with different pathologies, although the disruption efficacy and predominant type of degradation products depended on the amyloids' structure, size, and clustering. Notably, CTSB-induced irreversible degradation significantly reduced the toxicity for immortalized and primary cell lines of low-clustered fibrils, such as alpha-synuclein amyloids associated with Parkinson's disease. These findings enhance our understanding of how endogenous CTSB may regulate amyloid content at the molecular level in different neuropathologies. In addition, our results suggest the potential of CTSB as a component of anti-amyloid drugs in combination with agents that enhance the accessibility of proteolytic sites within amyloid clots and reduce these clusters stability.

The effect of glass container surface silanol density on monoclonal antibody formulation stability after application of mechanical shock

This study investigates the effect of silanol density on the surface of glass containers on the stability of monoclonal antibody (mAb) formulations subjected to mechanical stress. By calcining Type I glass containers at different temperatures, we altered the concentration of silanols on the glass surface and examined its impact on the stability of protein formulations under mechanical stress. Contact angle measurements and Fourier Transform Infrared (FTIR) spectroscopy indicated that silanol formation influences the hydrophilicity of the surface. Additionally, mAb solutions filled in Type I glass containers with varying silanol densities were repeatedly dropped from a height of 0.5 m to simulate mechanical stress during transport. The results demonstrated that increasing surface silanol density reduces protein monomer loss and the formation of protein aggregates and subvisible particles. Furthermore, protein aggregates and subvisible particles formed by dropping did not activate the complement in human serum in vitro. Adjusting the silanol density on the glass container surface offers an economical and environmentally friendly approach to improving the stability of mAb formulations during transportation.

Amyloids in bladder cancer hijack cancer-related proteins and are positive correlated to tumor stage

Despite the current diagnostic and therapeutic approaches to bladder cancer being widely accepted, there have been few significant advancements in this field over the past decades. This underscores the necessity for a paradigm shift in the approach to bladder cancer. The role of amyloids in cancer remains unclear despite their identification in several other pathologies. In this study, we present evidence of amyloids in bladder cancer, both in vitro and in vivo. In a murine model of bladder cancer, a positive correlation was observed between amyloids and tumor stage, indicating an association between amyloids and bladder cancer progression. Subsequently, the amyloid proteome of the RT4 non-invasive and HT1197 invasive bladder cancer cell lines was identified and included oncogenes, tumor suppressors, and highly expressed cancer-related proteins. It is proposed that amyloids function as structures that sequester key proteins. Therefore, amyloids should be considered in the study and diagnosis of bladder cancer.

Charge Modification of Lysine Mitigates Amyloid-β Aggregation

Alzheimer's disease (AD) is a progressive neurodegenerative condition characterized by the deposition of amyloid-β (Aβ) peptides, which aggregate into toxic structures such as oligomers, fibrils, and plaques. The presence of these Aβ aggregates in the brain plays a crucial role in the pathophysiology, leading to synaptic dysfunction and cognitive impairment. Understanding how physiological factors affect Aβ aggregation is essential, and therefore, exploring their influence in vitro will likely provide insights into their role in AD pathology. In this study, we investigated the effects of physiological, free amino acids on Aβ aggregation dynamics. We focused on positively charged amino acids, particularly lysine, and employed a chemical modification, methylation, to neutralize its charge. Our analyses revealed that modified lysine significantly reduced Aβ aggregation, indicating that charge distribution of amino acids plays a crucial role in modulating Aβ aggregation behavior. These findings enhance our understanding of the regulatory factors influencing Aβ aggregation and highlight important considerations for future research on Aβ.

Amyloid fibrils for β-carotene delivery - Influence of self-assembled structures on binding and in vitro release behavior

Two whey protein isolate amyloid fibrils (WPIF) with different structure were prepared, and the effects of these structures on binding of β-carotene (BC) and in vitro digestibility were evaluated. Whey protein isolate (WPI) in water (80 °C, pH 2.0) self-assembled into elongated WPIF (E-WPIF), whereas WPI formed to worm-like WPIF (W-WPIF) in trifluoroethanol. Compared to E-WPIF, W-WPIF showed higher surface hydrophobicity, indicating exposure of more hydrophobic residues. The encapsulation efficiency and loading capacity of BC in W-WPIF were higher than that of E-WPIF. The hydrophobic interaction were the main driving forces of WPIF/BC. During gastric digestion, WPIF lost intact fibrils structures, resulting in unordered small aggregates and most BC still bound to them. Then they were destroyed in the following intestinal digestion, leading to the release of BC. Compared with W-WPIF/BC, E-WPIF/BC had higher release of BC in gastrointestinal digestion due to weaker binding of BC and better digestibility of E-WPIF.

Aloin reduces advanced glycation end products, decreases oxidative stress, and enhances structural stability in glycated low-density lipoprotein

Glycation of proteins has been linked to several cardiovascular diseases, including atherosclerosis and diabetes mellitus. Various natural compounds have been explored for their anti-glycating ability. Aloin is the major anthraquinone glycoside, acquired from the Aloe species. This study focuses on aloin's anti-glycating and anti-oxidative potential on glycated low-density lipoprotein (LDL). Fluorescence studies related to anti-glycation showed that aloin significantly reduced the formation of fluorescent advanced glycation end-products (AGEs), hydrophobic environment, and fibrillar aggregates in glycated LDL. A decrease in oxidative stress markers was also seen in glycated LDL in the presence of aloin. Circular dichroism spectra depicted the positive role aloin played in restoring the secondary structure of LDL. Mode of binding between aloin and LDL were obtained through spectroscopic measurements, which revealed significant binding characteristics. Molecular docking studies confirmed the interaction with a binding energy of -8.5 kcal/mol, indicating a strong affinity between aloin and LDL. Furthermore, the stability of the aloin-LDL complex was validated by molecular dynamics simulations, showing that the secondary structure of LDL remained largely unchanged throughout the simulation period, indicating high stability of the complex. These findings open up new possibilities for using aloin in therapeutic applications aimed at cardiovascular health, potentially leading to the development of novel treatments or preventive measures for atherosclerotic cardiovascular diseases.

Toward a biological definition of neuronal and glial synucleinopathies

Cerebral accumulation of alpha-synuclein (αSyn) aggregates is the hallmark event in a group of neurodegenerative diseases-collectively called synucleinopathies-which include Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Currently, these are diagnosed by their clinical symptoms and definitively confirmed postmortem by the presence of αSyn deposits in the brain. Here, we summarize the drawbacks of the current clinical definition of synucleinopathies and outline the rationale for moving toward an earlier, biology-anchored definition of these disorders, with or without the presence of clinical symptoms. We underscore the utility of the αSyn seed amplification assay to detect aggregated αSyn in living patients and to differentiate between neuronal or glial αSyn pathology. We anticipate that a biological definition of synucleinopathies, if well-integrated with the current clinical classifications, will enable further understanding of the disease pathogenesis and contribute to the development of effective, disease-modifying therapies.

Efficient Biochemical Method for Characterizing and Classifying Related Amyloidogenic Peptides

Amyloidosis is a group of proteinopathies characterized by the systemic or organ-specific deposition of proteins in the form of amyloid fibers. Nearly 40 proteins play a role in these pathologies, and the structures of the associated fibers are beginning to be determined by Cryo-EM. However, the molecular events underlying the process, such as fiber nucleation and elongation, are poorly understood, which impairs developing efficient therapies. In most cases, only a few dozen amino acids of the pathological protein are found in the final structure of the fibers, while amyloid peptides comprising five to 10 amino acids are involved in the fiber nucleation process. The identification and biochemical characterization of these peptides are therefore of major scientific and clinical importance. We demonstrated that in silico approaches are limited due to the peptides' small size and long-distance intra- and intermolecular interactions that occur during nucleation. To address this problem, we developed a novel biochemical method for characterizing and classifying batches of related peptides. Initial work to optimize our approach is based on the reference peptide PHF6 (β1) from Microtubule-Associated Protein Tau (MAPT) as compared to 22 related peptides. Depending on their biochemical properties and using the Garnier-Delamarche plot we propose, we classified these peptides into three groups: aggregative, amyloid, and soluble (neither aggregative nor amyloid). We emphasize that our biochemical classification method is applicable to any family of peptides and could be scaled up for high-throughput analyses.

Novel Poly-Arginine Peptide R18D Reduces α-Synuclein Aggregation and Uptake of α-Synuclein Seeds in Cortical Neurons

BACKGROUND/OBJECTIVES

The role of α-synuclein (α-syn) pathology in Parkinson's disease (PD) is well established; however, effective therapies remain elusive. Two mechanisms central to PD neurodegeneration are the intracellular aggregation of misfolded α-syn and the uptake of α-syn aggregates into neurons. Cationic arginine-rich peptides (CARPs) are an emerging class of molecule with multiple neuroprotective mechanisms of action, including protein stabilisation. This study characterised both intracellular α-syn aggregation and α-syn uptake in cortical neurons in vitro. Thereafter, this study examined the therapeutic potential of the neuroprotective CARP, R18D (18-mer of D-arginine), to prevent the aforementioned PD pathogenic processes through a cell-free thioflavin-T (ThT) assay and in cortical neurons.

METHODS

To induce intracellular α-syn aggregation, rat primary cortical neurons were exposed to α-syn seed (0.14 μM) for 2 h to allow uptake of the protein, followed by R18D treatment (0.0625, 0.125, 0.25, 0.5 μM), and a subsequent measurement of α-syn aggregates 48 h later using a homogenous time-resolved fluorescence (HTRF) assay. To assess neuronal uptake, α-syn seeds were covalently labelled with an Alexa-Fluor 488 fluorescent tag, pre-incubated with R18D (0.125, 0.25, 0.5 μM), and then exposed to cortical neurons for 24 h and assessed via confocal microscopy.

RESULTS

It was demonstrated that R18D significantly reduced both intracellular α-syn aggregation and α-syn seed uptake in neurons by 37.8% and 77.7%, respectively. Also, R18D reduced the aggregation of α-syn monomers in the cell-free assay.

CONCLUSIONS

These findings highlight the therapeutic potential of R18D to inhibit key α-syn pathological processes and PD progression.

Amyloid inspired single amino acid (phenylalanine)-based supramolecular functional assemblies: from disease to device applications

In the evolving landscape of biomolecular supramolecular chemistry, recent studies on phenylalanine (Phe) have revealed important insights into the versatile nature of this essential aromatic amino acid. Phe can spontaneously self-assemble into fibrils with amyloid-like properties linked to the neurological disorder phenylketonuria (PKU). Apart from its pathological implications, Phe also displays complex phase behavior and can undergo structural changes in response to external stimuli. Its ability to co-assemble with other amino acids opens up new possibilities for studying biomolecular interactions. Furthermore, Phe's coordination with metal ions has led to the development of enzyme-mimicking catalytic systems for applications in organic chemistry, environmental monitoring, and healthcare. Research on L and D enantiomers of Phe, particularly on bio-MOFs, has highlighted their potential in advanced technologies, including bioelectronic devices. This review provides a comprehensive overview of the advancements in Phe-based supramolecular assemblies, emphasizing their interdisciplinary relevance. The Phe assemblies show great potential for future therapeutic and functional biomaterial developments, from disease treatments to innovations in bionanozymes and bioelectronics. This review presents a compelling case for the ongoing exploration of Phe's biomolecular supramolecular chemistry as a fundamental framework for developing sustainable and efficient methodologies across various scientific disciplines.

Hydroxycinnamic acids mediated modulation of α-Synuclein fibrillation: Biophysical insights

The fibrillation of α-synuclein (α-Syn) is considered a major contributor to Parkinson's disease (PD). Recent therapeutic measures have focused on inhibiting the fibrillation of α-Syn using various small molecules. We report here the effects of two different hydroxycinnamic acids; chlorogenic acid and sinapic acid on α-Syn fibrillation and have also discussed the mechanistic insights into their mode of modulation. The fluorescence spectroscopy shows that the two hydroxycinnamic acids bind with α-Syn with moderate affinity. Molecular docking studies provide a detailed insights into binding at the residue level and isothermal titration calorimetry reveals specific interactions, like hydrogen bonding, hydrophobic interactions, and van der Waals forces involved in the binding process. Fibrillation kinetics and transmission microscopic studies demonstrated that both chlorogenic acid and sinapic acid attenuate α-Syn fibrillation in a concentration dependent manner. Circular dichroism spectroscopy shows that these compounds bind with α-Syn and delay its structural transition in β-sheet containing fibrillar structures. Both the compounds are also effective even if added after the onset of fibrillation and the fibrillar species formed in the presence of these acids are unable to induce secondary nucleation in monomeric α-Syn. Such kind of structural and mechanistic insights are extremely crucial for designing therapeutic intervention in PD and other neurodegenerative diseases.

Disassembly and in vitro cell compatibility of α-lactalbumin particulates under physiologically relevant conditions

Protein self-assemblies in the form of ordered supramolecular structures such as particulates hold great potential as new biomaterials. However, research in this field is rarely conducted under physiologically relevant conditions but such studies are crucially needed to unravel the potential use of particulates and other amyloid structures in health sciences. In this study, particulates of α-lactalbumin (ALA) were prepared at different stages of maturation by thermal incubation. Disassembly of particulates in isotonic buffer, neutral pH and at 37 °C was investigated by simultaneously measuring Thioflavin T fluorescence intensity and light scattering. Freshly formed particulates quickly disassembled and displayed complete release of soluble ALA within 1 h. Mature particulates displayed slower disassembly kinetics with incomplete release of ALA within 1 h. The biocompatibility of particulates at different maturation stages to epithelial lung and fibroblast cells was assessed in vitro. Good cell compatibility was observed in the presence of the particulates and their released species. Our findings display protein particulates as biodegradable and highly tunable particles, promoting them as good candidates for drug delivery purposes.