Amyloid Fibrils Research Articles

Remediation of Metal Oxide Nanotoxicity with a Functional Amyloid.

Understanding the environmental health and safety of nanomaterials (NanoEHS) is essential for the sustained development of nanotechnology. Although extensive research over the past two decades has elucidated the phenomena, mechanisms, and implications of nanomaterials in cellular and organismal models, the active remediation of the adverse biological and environmental effects of nanomaterials remains largely unexplored. Inspired by recent developments in functional amyloids for biomedical and environmental engineering, this work shows their new utility as metallothionein mimics in the strategically important area of NanoEHS. Specifically, metal ions released from CuO and ZnO nanoparticles are sequestered through cysteine coordination and electrostatic interactions with beta-lactoglobulin (bLg) amyloid, as revealed by inductively coupled plasma mass spectrometry and molecular dynamics simulations. The toxicity of the metal oxide nanoparticles is subsequently mitigated by functional amyloids, as validated by cell viability and apoptosis assays in vitro and murine survival and biomarker assays in vivo. As bLg amyloid fibrils can be readily produced from whey in large quantities at a low cost, the study offers a crucial strategy for remediating the biological and environmental footprints of transition metal oxide nanomaterials.

Inhibition of amyloid fibrillation of single amino acid tryptophan by tannic acid: An insight into targeted therapy of hypertryptophanemia disorder

Amyloid fibrillation involving specific amino acids is a key factor contributing to the development of various neurodegenerative disorders, which remain being investigated. A promising therapeutic approach for treatment involves the use of small molecules to inhibit this amyloid fibrillation. In this study, we present experimental evidence demonstrating the efficacy of tannic acid (TA) as a potent inhibitor of fibrillation, particularly in the case of the single amino acid tryptophan (Trp), which is associated with hypertryptophanemia disorder. To investigate the kinetics of fibril formation and its suppression by TA, we have employed a combination of steady-state and time-resolved fluorescence measurements. These techniques have allowed us to monitor changes in the intrinsic fluorescence of Trp and an amyloid-specific fluorophore over time. To visualize the effects of TA on Trp fibrils, we have employed various imaging techniques such as, atomic force microscopy, transmission electron microscopy, and field emission scanning electron microscopy. These imaging techniques have vividly captured the TA-induced disruption of long Trp fibrils. Dynamic light scattering measurements have complemented these microscopic observations, further supporting the notion that TA effectively hinders the formation and stability of Trp fibrils. Additionally, we have determined the binding constant and calculated changes in the free energy associated with Trp-TA interactions through temperature-dependent spectroscopic measurements. These thermodynamic analyses provide valuable insights into the underlying mechanisms of TA-induced disaggregation of larger Trp fibrils.

Structure-Toxicity Relationship in Intermediate Fibrils from α-Synuclein Condensates.

The aberrant aggregation of α-synuclein (αS) into amyloid fibrils is associated with a range of highly debilitating neurodegenerative conditions, including Parkinson's disease. Although the structural properties of mature amyloids of αS are currently understood, the nature of transient protofilaments and fibrils that appear during αS aggregation remains elusive. Using solid-state nuclear magnetic resonance (ssNMR), cryogenic electron microscopy (cryo-EM), and biophysical methods, we here characterized intermediate amyloid fibrils of αS forming during the aggregation from liquid-like spherical condensates to mature amyloids adopting the structure of pathologically observed aggregates. These transient amyloid intermediates, which induce significant levels of cytotoxicity when incubated with neuronal cells, were found to be stabilized by a small core in an antiparallel β-sheet conformation, with a disordered N-terminal region of the protein remaining available to mediate membrane binding. In contrast, mature amyloids that subsequently appear during the aggregation showed different structural and biological properties, including low levels of cytotoxicity, a rearranged structured core embedding also the N-terminal region, and a reduced propensity to interact with the membrane. The characterization of these two fibrillar forms of αS, and the use of antibodies and designed mutants, enabled us to clarify the role of critical structural elements endowing intermediate amyloid species with the ability to interact with membranes and induce cytotoxicity.

Cutaneous amyloidosis in a patient with systemic amyloidosis due to multiple myeloma

Cutaneous manifestations in systemic amyloidosis secondary to multiple myeloma or AL amyloidosis are seen in approximately 15%-40% of patients with systemic amyloidosis. Cutaneous involvement has a preference for skin folds, retroauricular region, eyelids, neck and the axilla and may present in the form of purpura, domed papules or nodes resembling isolated nodular amyloidosis. Congo red staining remains the gold standard for diagnosis, revealing amyloid fibrils with apple-green birefringence in the polarized microscopy. It is noteworthy that patients may sometimes present with non-specific skin changes, suggestive of depositional disease, such as alopecia or nail dystrophy. Herein, we present a patient with systemic amyloidosis, who exhibited red-brown macules coalescing into a rippled pattern in the extremities, amyloid nodules in the peri-auricular region and dystrophic nails, findings that were attricuted to cutaneous amyloidosis in the context of systemic amyloidosis.

New Development in Amyloidosis Research Based on Supersaturation: Biological Factors to Induce/Inhibit the Amyloid Fibril Formation

Amyloid fibril formation is a general property of proteins and peptides. It is a physicochemical phenomenon similar to crystallization, in which amyloid precursor proteins exceeding solubility precipitate through the breakdown of supersaturation. Using the ultrasonication-forced amyloid fibril inducer HANABI, we have discovered that serum albumin acts as an inhibitor in dialysis-related amyloidosis. Exploring the factors that induce or inhibit amyloid fibril formation using HANABI can lead to the development of early diagnosis and prevention methods for amyloidosis.

Functionalized activated carbon with whey protein amyloid fibrils for adsorption of arsenic from water

Globally, more than 200 million people are exposed to elevated concentrations of arsenic in groundwater, thus representing an important environmental and public health problem. Apart from inorganic species, water quality suffers also from the occurrence of organic pollutants discharged by the food sector like whey, a by-product of the dairy industry. The valorisation of these organic residues is relevant to reduce water pollution and to develop new materials for different applications. This research reports the synthesis and evaluation of a novel adsorptive activated carbon composite modified with whey protein amyloids for arsenic removal from water. The adsorbent was characterized with FT-IR spectroscopy, X-ray diffraction, N2 physisorption, pH at point of zero charge determination, and thermogravimetric analysis. Experimental adsorption kinetics and isotherms of arsenic removal were determined at optimal pH 5.0, best fitted with the PSO and Sips model, respectively. The corresponding maximum adsorption capacity for As5+ was 0.16 mmol g−1 through an endothermic process. Surface complexation was the predominant phenomenon in the adsorption mechanism as the As-O bond was formed via whey’s functional groups, hydroxyl, amine, and amide, with the latter having the strong affinity to arsenate as elucidated by the HSAB theory. This study highlights the potential of whey protein as a raw material to produce added-value products and its performance as a precursor of novel adsorbents for water purification, therefore minimizing their associated disposal cost and addressing relevant environmental concerns such as arsenic contamination.

A Comprehensive Review on Chemistry and Biology of Tafamidis in Transthyretin Amyloidosis.

Transthyretin amyloid cardiomyopathy and Transthyretin amyloid peripheral neuropathy are progressive disease conditions caused by Transthyretin amyloidosis (ATTR) fibril infiltration in the tissue. Transthyretin (TTR) protein misfolding and amyloid fibril deposits are pathological biomarkers of ATTR-related disorders. There are various treatment strategies targeting different stages in pathophysiology. One such strategy is TTR tetramer stabilization. Recently, a new TTR tetramer stabilizer, tafamidis, has been introduced that reduces the protein misfolding and amyloidosis and, consequently, disease progression in ATTR cardiomyopathy and peripheral neuropathy. This review will provide a comprehensive overview of the literature on tafamidis discovery, development, synthetic methods, pharmacokinetics, analytical methods and clinical trials. Overall, 7 synthetic methods, 5 analytical methods and 23 clinical trials have been summarized from the literature.

Cardiac amyloidosis – A rarely acknowledged cause of heart failure: A case report and review of literature

Amyloidosis is characterized by the precipitation of insoluble, misfolded, fibrillary proteins in the extracellular matrix in the form of beta-pleated sheets, leading to the loss of normal tissue architecture and ultimately organ dysfunction. The manifestations of the disease are due to the noxious effects of aggregated proteins (Amyloid) deposited in the tissues. Amyloidosis involves multiple organs, including the heart, kidneys, liver, soft tissues, peripheral and/or autonomic nervous system, and gastrointestinal tract. Cardiac amyloidosis is one of the myriad manifestations of systemic amyloidosis. It is characterized by extracellular deposition of amyloid fibrils, leading to progressive cardiac failure. We report a case of a 54-year-old male, who presented to us with a history of exertional dyspnea for the past 2 years with left ventricular systolic and diastolic dysfunction unexplained by the coronary anatomy. The findings on cardiac imaging led us to the suspicion of cardiac amyloidosis. Further, evaluation with an abdominal fat pad and rectal mucosal biopsy confirmed amyloidosis.

Role of Palliative Care in the Supportive Management of AL Amyloidosis-A Review.

Light chain amyloidosis is a plasma-cell disorder with a poor prognosis. It is a progressive condition, causing worsening pain, disability, and life-limiting complications involving multiple organ systems. The medical regimen can be complex, including chemotherapy or immunotherapy for the disease itself, as well as treatment for pain, gastrointestinal and cardiorespiratory symptoms, and various secondary symptoms. Patients and their families must have a realistic awareness of the illness and of the goals and limitations of treatments in making informed decisions about medical therapy, supportive management, and end-of-life planning. Palliative care services can thus improve patients' quality of life and may even reduce overall treatment costs. Light chain (AL) amyloidosis is a clonal plasma cell disorder characterized by the excessive secretion of light chains by an indolent plasma cell clone that gradually accumulates in vital organs as amyloid fibrils and leads to end-organ damage. With progressive disease, most patients develop diverse clinical symptoms and complications that negatively impact quality of life and increase mortality. Complications include cardiac problems including heart failure, hypotension, pleural effusions, renal involvement including nephrotic syndrome with peripheral edema, gastrointestinal symptoms leading to anorexia and cachexia, complex pain syndromes, and mood disorders. The prognosis of patients with advanced AL amyloidosis is dismal. With such a complex presentation, and high morbidity and mortality rates, there is a critical need for the establishment of a palliative care program in clinical management. This paper provides an evidence-based overview of the integration of palliative care in the clinical management of AL amyloidosis as a means of reducing ER visits, rehospitalizations, and in-hospital mortality. We also discuss potential future collaborative directions in various aspects of clinical care related to AL amyloidosis.

Hairpin trimer transition state of amyloid fibril

Protein fibril self-assembly is a universal transition implicated in neurodegenerative diseases. Although fibril structure/growth are well characterized, fibril nucleation is poorly understood. Here, we use a computational-experimental approach to resolve fibril nucleation. We show that monomer hairpin content quantified from molecular dynamics simulations is predictive of experimental fibril formation kinetics across a tau motif mutant library. Hairpin trimers are predicted to be fibril transition states; one hairpin spontaneously converts into the cross-beta conformation, templating subsequent fibril growth. We designed a disulfide-linked dimer mimicking the transition state that catalyzes fibril formation, measured by ThT fluorescence and TEM, of wild-type motif - which does not normally fibrillize. A dimer compatible with extended conformations but not the transition-state fails to nucleate fibril at any concentration. Tau repeat domain simulations show how long-range interactions sequester this motif in a mutation-dependent manner. This work implies that different fibril morphologies could arise from disease-dependent hairpin seeding from different loci.

Dissecting the effect of ALS mutation S375G on the conformational properties and aggregation dynamics of TDP-43370-375 fragment

The aggregation of transactive response deoxyribonucleic acid (DNA) binding protein of 43 kDa (TDP-43) into ubiquitin-positive inclusions is closely associated with amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration, and chronic traumatic encephalopathy. The 370–375 fragment of TDP-43 (370GNNSYS375, TDP-43370-375), the amyloidogenic hexapeptides, can be prone to forming pathogenic amyloid fibrils with the characteristic of steric zippers. Previous experiments reported the ALS-associated mutation, serine 375 substituted by glycine (S375G) is linked to early onset disease and protein aggregation of TDP-43. Based on this, it is necessary to explore the underlying molecular mechanisms. By utilizing all-atom molecular dynamics (MD) simulations of 102 μs in total, we investigated the impact of S375G mutation on the conformational ensembles and oligomerization dynamics of TDP-43370-375 peptides. Our replica exchange MD simulations show that S375G mutation could promote the unstructured conformation formation and induce peptides to form a loose packed oligomer, thus inhibiting the aggregation of TDP-43370-375. Further analyses suggest that S375G mutation displays a reduction effect on the number of total hydrogen bonds and contacts among TDP-43370-375 peptides. Hydrogen bonding and polar interactions among TDP-43370-375 peptides, as well as Y374-Y374 π-π stacking interaction, are attenuated by S375G mutation. Additional microsecond MD simulations demonstrate that S375G mutation could prohibit the conformational conversion to β-structure-rich aggregates and possess an inhibitory effect on the oligomerization dynamics of TDP-43370-375. This study offers for the first time of molecular insights into the S375G mutation affecting the aggregation of TDP-43370-375 at the atomic level, and may open new avenues in the development of future site-specific mutation therapeutics.

Functional amyloid fibrils of biofilm-forming marine bacterium Pseudomonas aeruginosa PFL-P1 interact spontaneously with pyrene and augment the biodegradation

Bacteria thrive in biofilms embedding in the three-dimensional extracellular polymeric substances (EPS). Functional Amyloid in Pseudomonas (Fap), a protein in EPS, efficiently sequesters polycyclic aromatic hydrocarbons (PAHs). Present study reports the characterization of Fap fibrils from Pseudomonas aeruginosa PFL-P1 and describes the interaction with pyrene to assess the impact on pyrene degradation. Overexpression of fap in E. coli BL21(DE3) cells significantly enhances biofilm formation (p < 0.0001) and amyloid production (p = 0.0002), particularly with pyrene. Defibrillated Fap analysis reveals FapC monomers and increased fibrillation with pyrene. Circular Dichroism (CD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) unveil characteristic amyloid peaks and structural changes in Fap fibrils upon pyrene exposure. 3D-EEM analysis identifies a protein-like fluorophore in Fap fibrils, exhibiting pyrene-induced fluorescence quenching. Binding constants range from 5.23 to 7.78 M−1, with ΔG of −5.10 kJ mol−1 at 298 K, indicating spontaneous and exothermic interaction driven by hydrophobic forces. Exogenous Fap fibrils substantially increased the biofilm growth and pyrene degradation by P. aeruginosa PFL-P1 from 46 % to 64 % within 7 days (p = 0.0236). GC–MS identifies diverse metabolites, implying phthalic acid pathway in pyrene degradation. This study deepens insights into structural dynamics of Fap fibrils when exposed to pyrene, offering potential application in environmental bioremediation.

The role of shear rates on amyloid formation from biofilm peptide phenol-soluble modulins

Biofilms, microbial communities enclosed in the self-produced extracellular matrix, have a significant impact on human health, environment, and industry. The pathogen Staphylococcus aureus (S. aureus) is recognized as one of the most frequent causes of biofilm-related infections. Phenol-soluble modulins (PSMs) serve as a crucial component, fortifying S. aureus biofilm matrix through self-assembly into amyloid fibrils, which enhances S. aureus colonization and resistance to antibiotics. However, the role of shear rate, one of the critical physiological factors within blood vessels, on the formation of PSM amyloids remains poorly understood. In this work, using a combination of thioflavin T fluorescence kinetic studies, circular dichroism spectrometry, and electron microscopy, we demonstrated that shear rates ranging from 150 to 300 s−1 accelerate fibrillation of PSMα1, α3, and α4 into amyloids, resulting in elongated amyloid structures. Furthermore, PSMα1, α3, and α4 predominantly self-assembled into amyloid fibers with a cross-α structure under shear conditions, deviating from the typical β-sheet configuration of PSM amyloids. These findings imply the role of shear rates within the bloodstream on enhancing PSM self-assembly that is associated with S. aureus biofilm formation.

Phosphorylation and O-GlcNAcylation at the same α-synuclein site generate distinct fibril structures

α-Synuclein forms amyloid fibrils that are critical in the progression of Parkinson’s disease and serves as the pathological hallmark of this condition. Different posttranslational modifications have been identified at multiple sites of α-synuclein, influencing its conformation, aggregation and function. Here, we investigate how disease-related phosphorylation and O-GlcNAcylation at the same α-synuclein site (S87) affect fibril structure and neuropathology. Using semi-synthesis, we obtained homogenous α-synuclein monomer with site-specific phosphorylation (pS87) and O-GlcNAcylation (gS87) at S87, respectively. Cryo-EM revealed that pS87 and gS87 α-synuclein form two distinct fibril structures. The GlcNAc situated at S87 establishes interactions with K80 and E61, inducing a unique iron-like fold with the GlcNAc molecule on the iron handle. Phosphorylation at the same site prevents a lengthy C-terminal region including residues 73 to 140 from incorporating into the fibril core due to electrostatic repulsion. Instead, the N-terminal half of the fibril (1–72) takes on an arch-like fibril structure. We further show that both pS87 and gS87 α-synuclein fibrils display reduced neurotoxicity and propagation activity compared with unmodified α-synuclein fibrils. Our findings demonstrate that different posttranslational modifications at the same site can produce distinct fibril structures, which emphasizes link between posttranslational modifications and amyloid fibril formation and pathology.

Bovine serum albumin uptake and polypeptide disaggregation studies of hypoglycemic ruthenium(II) uracil Schiff-base complexes

Our prior studies have illustrated that the uracil ruthenium(II) diimino complex, [Ru(H3ucp)Cl(PPh3)] (1) (H4ucp = 2,6-bis-((6-amino-1,3-dimethyluracilimino)methylene)pyridine) displayed high hypoglycemic effects in diet-induced diabetic rats. To rationalize the anti-diabetic effects of 1, three new derivatives have been prepared, cis-[Ru(bpy)2(urdp)]Cl2 (2) (urdp = 2,6-bis-((uracilimino)methylene)pyridine), trans-[RuCl2(PPh3)(urdp)] (3), and cis-[Ru(bpy)2(H4ucp)](PF6)2 (4). Various physicochemical techniques were utilized to characterize the structures of the novel ruthenium compounds. Prior to biomolecular interactions or in vitro studies, the stabilities of 1–4 were monitored in anhydrous DMSO, aqueous phosphate buffer containing 2% DMSO, and dichloromethane (DCM) via UV–Vis spectrophotometry. Time-dependent stability studies showed ligand exchange between DMSO nucleophiles and chloride co-ligands of 1 and 3, which was suppressed in the presence of an excess amount of chloride ions. In addition, the metal complexes 1 and 3 are stable in both DCM and an aqueous phosphate buffer containing 2% DMSO. In the case of compounds 2 and 4 with no chloride co-ligands within their coordination spheres, high stability in aqueous phosphate buffer containing 2% DMSO was observed. Fluorescence emission titrations of the individual ruthenium compounds with bovine serum albumin (BSA) showed that the metal compounds interact non-discriminately within the protein's hydrophobic cavities as moderate to strong binders. The metal complexes were capable of disintegrating mature amylin amyloid fibrils. In vivo glucose metabolism studies in liver (Chang) cell lines confirmed enhanced glucose metabolism as evidenced by the increased glucose utilization and glycogen synthesis in liver cell lines in the presence of complexes 2–4.

Anion–Induced Amyloid Fibrillation of Human Insulin In vitro

AbstractIn the present study, we have focused on the effect of three biologically important salt anions on insulin aggregation. The result of the present study reveals that salts differing in their anions (NaI, NaOAc, and NaNO3) induce the self–assembly formation of insulin even at low physiological (in the micromolar range) salt concentration with efficacy that follows the order I−&gt;CH3COO−&gt;NO3−. Here, the anion–driven aggregation of insulin does not follow either the Hofmeister series or electroselectivity series at very low salt concentrations; instead, the binding of anions at low pH to the positively charged residues of insulin is determined by a mechanism where the salt anions promote the fibrillation of insulin and modify the morphology of the monomeric precursor molecule. Both the nucleation and fibril elongation are controlled by the electrostatic forces and hydrophobic interactions. Aggregation mechanism and aggregate morphology were investigated employing a combination of Thioflavin T (ThT) and ANS fluorescence, circular dichroism (CD), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Overall, the present data will enhance the idea to rationalize the anion effects on the aggregation of amyloid‐prone protein and to understand the influence of charged biomolecules in cellular compartments.

The Inhibition Mechanisms of Three Structurally Different Salvianolic Acids on the Non-Enzymatic Glycation of Bovine Serum Albumin.

The antiglycation mechanisms of three structurally different salvianolic acids (Sals) including salvianolic acid A (Sal-A), salvianolic acid B (Sal-B) and salvianolic acid C (Sal-C) were investigated using the bovine serum albumin (BSA)-fructose model. The results showed that the three compounds could inhibit the formation of glycation products, maintain protein structural stability, mitigate the development of amyloid fibrils and scavenge radicals. Notably, Sal-A possessed the highest anti-glycated activity compared with Sal-B and Sal-C. This may be related to the fact that Sal-A contained the most molecules of caffeic acid (Sal-A, Sal-B, and Sal-C possessing two, one, and zero caffeic acid units, respectively), and caffeic acid played a leading role in the antiglycation properties relative to Danshensu. Moreover, these compounds quenched the intrinsic fluorescence intensity of BSA in a static mode, with the binding constants in the order of Sal-A > Sal-B > Sal-C. Obviously, Sal-A possessed the strongest binding affinity among these compounds, which may be one of the reasons why it exhibited the optimal antiglycation capability. Furthermore, molecular docking demonstrated that the three Sals exerted protective effects on BSA by preventing glycation modification of lysine and arginine residues. These findings would provide valuable insights into the potential application of Sals for alleviating non-enzymatic glycation of protein.

Effect of caffeine on the aggregation of amyloid-β-A 3D RISM study.

Alzheimer's disease is a detrimental neurological disorder caused by the formation of amyloid fibrils due to the aggregation of amyloid-β peptide. The primary therapeutic approaches for treating Alzheimer's disease are targeted to prevent this amyloid fibril formation using potential inhibitor molecules. The discovery of such inhibitor molecules poses a formidable challenge to the design of anti-amyloid drugs. This study investigates the effect of caffeine on dimer formation of the full-length amyloid-β using a combined approach of all-atom, explicit water molecular dynamics simulations and the three-dimensional reference interaction site model theory. The change in the hydration free energy of amyloid-β dimer, with and without the inhibitor molecules, is calculated with respect to the monomeric amyloid-β, where the hydration free energy is decomposed into energetic and entropic components, respectively. Dimerization is accompanied by a positive change in the partial molar volume. Dimer formation is spontaneous, which implies a decrease in the hydration free energy. However, a reverse trend is observed for the dimer with inhibitor molecules. It is observed that the negatively charged residues primarily contribute for the formation of the amyloid-β dimer. A residue-wise decomposition reveals that hydration/dehydration of the side-chain atoms of the charged amino acid residues primarily contribute to dimerization.

Fluorescence study of the interaction between albumin and layered double hydroxides

Layered double hydroxides nanoparticles (LDH-NP) are increasingly studied for biomedical applications. Nevertheless, their interaction with biomolecules such as proteins needs further exploration for an effective application. In this work, the adsorption of bovine serum albumin (BSA) on LDH-NP and the conformation changes of the protein upon adsorption were characterized using fluorescence spectroscopy. First, the quenching of tryptophan residues of BSA by chloride-intercalated LDH-NP was explored and the BSA adsorption capacity of LDH-NP were determined. Then, the structural conformation of the protein was analyzed by fluorescence spectroscopy (including synchronous, polarization and quenching studies) at different surface coverages. Finally, the proclivity of adsorbed BSA molecules to assemble as amyloid fibril was evaluated. Due to the positive charging and low curvature of LDH-NP, BSA molecules were strongly adsorbed, which produced a quenching of the protein fluorescence and a large adsorption capacity. The effect on BSA conformation was dependent on surface coverage (SC): at low values ,t he tryptophan residues were in more hydrophobic environments and more accessible to quenchers than al high ones. At low SC, there is space between the BSA molecules to spread on the surface, which led to a conformation change. Contrarily, the native conformation around tryptophan residues of BSA was preserved at high SC due to the tight packing of the adsorbed protein molecules. As a result, BSA molecules are stabilized against the formation of amyloid fibrils at high SC, while at low SC they present a similar fibrillation than free BSA.

Combining different ionic polysaccharides and pH treatment improved functional properties of soybean protein amyloid fibrils through structural modifications

This paper reported the effects of different ionic polysaccharides (a cationic polysaccharide (chitosan, CTS), an anionic polysaccharide (high methoxyl pectin, HMP), and a neutral polysaccharide (dextran, DEX)) and pHs (2.0, 4.5, 7.0, and 9.0) on the structural and functional properties of soybean protein amyloid fibrils (SAF) under non-covalent interactions. The fluorescence spectroscopy, ζ-potential, surface hydrophobicity (H0), and turbidity analyses revealed that, at any pH, HMP had a greater effect on the structure of SAF than CTS or DEX. Electrostatic and hydrophobic interactions predominated between SAF and HMP. The addition of negatively charged HMP prevented the exposure of hydrophobic groups, the H0 and ζ-potential decreased. Moreover, compared to SAF, the rheological properties of SAF-HMP complexes were enhanced. In particular, at pH 2.0, HMP was crosslinked with SAF and changed the fibrils conformation, the foaming stability of SAF-HMP increased to 100%. Furthermore, at pHs 2.0 and 4.5, strong electrostatic repulsion occurred between CTS and SAF. Therefore, SAF-CTS exhibited the highest emulsifying activity index and emulsifying stability index, which are 58.21 m2/g and 41.76 min, respectively, followed by SAF-HMP. By contrast, DEX had the least influence on the fibrils. These results will give a hand for industrial production of soybean protein amyloid fibrils.