The Experts below are selected from a list of 8634 Experts worldwide ranked by ideXlab platform
David B Teplow - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of key kinetic intermediates in amyloid beta protein Fibrillogenesis
Journal of Molecular Biology, 2001Co-Authors: Marina D Kirkitadze, Margaret M Condron, David B TeplowAbstract:Abstract Amyloid β-protein (Aβ) assembly into toxic oligomeric and fibrillar structures is a seminal event in Alzheimer’s disease, therefore blocking this process could have significant therapeutic benefit. A rigorous mechanistic understanding of Aβ assembly would facilitate the targeting and design of Fibrillogenesis inhibitors. Prior studies have shown that Aβ Fibrillogenesis involves conformational changes leading to the formation of extended β-sheets and that an α-helix-containing intermediate may be involved. However, the significance of this intermediate has been a matter of debate. We report here that the formation of an oligomeric, α-helix-containing assembly is a key step in Aβ Fibrillogenesis. The generality of this phenomenon was supported by conformational studies of 18 different Aβ peptides, including wild-type Aβ(1–40) and Aβ(1–42), biologically relevant truncated and chemically modified Aβ peptides, and Aβ peptides causing familial forms of cerebral amyloid angiopathy. Without exception, Fibrillogenesis of these peptides involved an oligomeric α-helix-containing intermediate and the kinetics of formation of the intermediate and of fibrils was temporally correlated. The kinetics varied depending on amino acid sequence and the extent of peptide N- and C-terminal truncation. The pH dependence of helix formation suggested that Asp and His exerted significant control over this process and over Fibrillogenesis in general. Consistent with this idea, Aβ peptides containing Asp → Asn or His → Gln substitutions showed altered Fibrillogenesis kinetics. These data emphasize the importance of the dynamic interplay between Aβ monomer conformation and oligomerization state in controlling Fibrillogenesis kinetics.
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structural and kinetic features of amyloid β protein Fibrillogenesis
Amyloid, 1998Co-Authors: David B TeplowAbstract:Alzheimer's disease (AD) is an archetype of a class of diseases characterized by abnormal protein deposition. in each case, deposition manifests itself in the form of amyloid deposits composed of fibrils of otherwise normal, soluble proteins or peptides. An ever-increasing body of genetic, physiologic, and biochemical data supports the hypothesis that Fibrillogenesis of the amyloid β-protein is a seminal event in Alzheimer's disease. Inhibiting Aβ Fibrillogenesis is thus an important strategy for AD therapy. However, before this strategy can be implemented, a mechanistic understanding of the Fibrillogenesis process must be achieved and appropriate steps selected as therapeutic targets. Following a brief introduction to AD, I review here the current state of knowledge of Aβ Fibrillogenesis. Special emphasis is placed on the morphologic, structural, and kinetic aspects of this complex process.
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amyloid β protein Fibrillogenesis detection of a protofibrillar intermediate
Journal of Biological Chemistry, 1997Co-Authors: Dominic M Walsh, Aleksey Lomakin, George B Benedek, Margaret M Condron, David B TeplowAbstract:Abstract Fibrillogenesis of the amyloid β-protein (Aβ) is a seminal pathogenetic event in Alzheimer’s disease. Inhibiting Fibrillogenesis is thus one approach toward disease therapy. Rational design of Fibrillogenesis inhibitors requires elucidation of the stages and kinetics of Aβ Fibrillogenesis. We report results of studies designed to examine the initial stages of Aβ oligomerization. Size exclusion chromatography, quasielastic light scattering spectroscopy, and electron microscopy were used to characterize Fibrillogenesis intermediates. After dissolution in 0.1 m Tris-HCl, pH 7.4, and removal of pre-existent seeds, Aβ chromatographed almost exclusively as a single peak. The molecules composing the peak had average hydrodynamic radii of 1.8 ± 0.2 nm, consistent with the predicted size of dimeric Aβ. Over time, an additional peak, with a molecular weight >100,000, appeared. This peak contained predominantly curved fibrils, 6–8 nm in diameter and <200 nm in length, which we have termed “protofibrils.” The kinetics of protofibril formation and disappearance are consistent with protofibrils being intermediates in the evolution of amyloid fibers. Protofibrils appeared during the polymerization of Aβ-(1–40), Aβ-(1–42), and Aβ-(1–40)-Gln22, peptides associated with both sporadic and inherited forms of Alzheimer’s disease, suggesting that protofibril formation may be a general phenomenon in Aβ Fibrillogenesis. If so, protofibrils could be attractive targets for Fibrillogenesis inhibitors.
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Amyloid β-Protein Fibrillogenesis DETECTION OF A PROTOFIBRILLAR INTERMEDIATE
Journal of Biological Chemistry, 1997Co-Authors: Dominic M Walsh, Aleksey Lomakin, George B Benedek, Margaret M Condron, David B TeplowAbstract:Abstract Fibrillogenesis of the amyloid β-protein (Aβ) is a seminal pathogenetic event in Alzheimer’s disease. Inhibiting Fibrillogenesis is thus one approach toward disease therapy. Rational design of Fibrillogenesis inhibitors requires elucidation of the stages and kinetics of Aβ Fibrillogenesis. We report results of studies designed to examine the initial stages of Aβ oligomerization. Size exclusion chromatography, quasielastic light scattering spectroscopy, and electron microscopy were used to characterize Fibrillogenesis intermediates. After dissolution in 0.1 m Tris-HCl, pH 7.4, and removal of pre-existent seeds, Aβ chromatographed almost exclusively as a single peak. The molecules composing the peak had average hydrodynamic radii of 1.8 ± 0.2 nm, consistent with the predicted size of dimeric Aβ. Over time, an additional peak, with a molecular weight >100,000, appeared. This peak contained predominantly curved fibrils, 6–8 nm in diameter and
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on the nucleation and growth of amyloid beta protein fibrils detection of nuclei and quantitation of rate constants
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Aleksey Lomakin, George B Benedek, Doo Soo Chung, Daniel A Kirschner, David B TeplowAbstract:We have studied the Fibrillogenesis of synthetic amyloid beta-protein-(1-40) fragment (A beta) in 0.1 M HCl. At low pH, A beta formed fibrils at a rate amenable to detailed monitoring by quasi-elastic light-scattering spectroscopy. Examination of the fibrils with circular dichroism spectroscopy and electron microscopy showed them to be highly similar to those found in amyloid plaques. We determined the hydrodynamic radii of A beta aggregates during the entire process of fibril nucleation and growth. Above an A beta concentration of approximately 0.1 mM, the initial rate of elongation and the final size of fibrils were independent of A beta concentration. Below an A beta concentration of 0.1 mM, the initial elongation rate was proportional to the peptide concentration, and the resulting fibrils were significantly longer than those formed at higher concentration. We also found that the surfactant n-dodecylhexaoxyethylene glycol monoether (C12E6) slowed nucleation and elongation of fibrils in a concentration-dependent manner. Our observations are consistent with a model of A beta Fibrillogenesis that includes the following key steps: (i) peptide micelles form above a certain critical A beta concentration, (ii) fibrils nucleate within these micelles or on heterogeneous nuclei (seeds), and (iii) fibrils grow by irreversible binding of monomers to fibril ends. Interpretation of our data enabled us to determine the sizes of fibril nuclei and A beta micelles and the rates of fibril nucleation (from micelles) and fibril elongation. Our approach provides a powerful means for the quantitative assay of A beta Fibrillogenesis.
David E. Birk - One of the best experts on this subject based on the ideXlab platform.
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Fibromodulin Regulates Collagen Fibrillogenesis During Peripheral Corneal Development
Developmental Dynamics, 2010Co-Authors: Shoujun Chen, Shukti Chakravarti, Ake Oldberg, David E. BirkAbstract:Fibromodulin regulates collagen Fibrillogenesis, but its existence/role(s) in the cornea is controversial. We hypothesize that fibromodulin regulates Fibrillogenesis during postnatal development of the anterior eye. Fibromodulin is weakly expressed in the limbus at post-natal day (P) 4, increases and extends into the central cornea at P14, becomes restricted to the limbus at P30, and decreases at P60. This differential spatial and temporal expression of fibromodulin is coordinated with emmetropization; the developmental increase in axial length and globe size. Genetic analysis demonstrated that fibromodulin regulates Fibrillogenesis in a region-specific manner. At the limbus, fibromodulin is dominant in regulating fibril growth during postnatal development. In the posterior peripheral cornea, cooperative interactions of fibromodulin and lumican regulate Fibrillogenesis. These data indicate that fibromodulin plays important roles in the regulation of region-specific Fibrillogenesis required for the integration of the corneal and scleral matrices and sulcus development required for establishment of the visual axis. Developmental Dynamics 239:844-854, 2010 (C) 2010 Wiley-Liss, Inc.
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type xiv collagen regulates Fibrillogenesis premature collagen fibril growth and tissue dysfunction in null mice
Journal of Biological Chemistry, 2009Co-Authors: Heather L Ansorge, Xianmin Meng, Guiyun Zhang, Guido Veit, John F Klement, David P Beason, Louis J Soslowsky, Manuel Koch, David E. BirkAbstract:Type XIV collagen is a fibril-associated collagen with an interrupted triple helix. This collagen interacts with the fibril surface and has been implicated as a regulator of Fibrillogenesis; however, a specific role has not been elucidated. Functional roles for type XIV collagen were defined utilizing a new type XIV collagen-deficient mouse line. This line was produced using a conventional targeted knock-out approach. Col14a1(–/–) mice were devoid of type XIV collagen, whereas heterozygous mice had reduced synthesis. Both mutant Col14a1 genotypes were viable with a grossly normal phenotype; however, mature skin exhibited altered mechanical properties. Prior to evaluating tendon Fibrillogenesis in type XIV collagen-deficient mice, the developmental expression patterns were analyzed in wild-type flexor digitorum longus (FDL) tendons. Analyses of mRNA and protein expression indicated tissue-specific temporal expression that was associated with the early stages in Fibrillogenesis. Ultrastructural analyses of wild-type and null tendons demonstrated premature fibril growth and larger fibril diameters in tendons from null mice at postnatal day 4 (P4). However, fibril structure in mature tendons was normal. Biomechanical studies established a direct structure/function relationship with reduced strength in P7-null tendons. However, the biomechanical properties in P60 tendons were comparable in null and wild-type mice. Our results indicate a regulatory function for type XIV collagen in early stages of collagen Fibrillogenesis with tissue differences.
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development of tendon structure and function regulation of collagen Fibrillogenesis
Journal of Musculoskeletal & Neuronal Interactions, 2005Co-Authors: Gao Zhang, Shukti Chakravarti, Yoichi Ezura, Louis J Soslowsky, Blanche Young, Michele Favata, David E. BirkAbstract:In the tendon, the development of mature mechanical properties is dependent on the assembly of a tendon-specific extracellular matrix. This matrix is synthesized by the tendon fibroblasts and composed of collagen fibrils organized as fibers, as well as fibril-associated collagenous and non-collagenous proteins. All of these components are integrated, during development and growth, to form a functional tissue. During tendon development, collagen Fibrillogenesis and matrix assembly progress through multiple steps where each step is regulated independently, culminating in a structurally and functionally mature tissue. Collagen Fibrillogenesis occurs in a series of extracellular compartments where fibril intermediates are assembled and mature fibrils grow through a process of post-depositional fusion of the intermediates. Linear and lateral fibril growth occurs after the immature fibril intermediates are incorporated into fibers. The processes are regulated by interactions of extracellular macromolecules with the fibrils. Interactions with quantitatively minor fibrillar collagens, fibril-associated collagens and proteoglycans influence different steps in Fibrillogenesis and the extracellular microdomains provide a mechanism for the tendon fibroblasts to regulate these extracellular interactions.
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differential expression of lumican and fibromodulin regulate collagen Fibrillogenesis in developing mouse tendons
Journal of Cell Biology, 2000Co-Authors: Yoichi Ezura, Shukti Chakravarti, Inna Chervoneva, Ake Oldberg, David E. BirkAbstract:Collagen Fibrillogenesis is finely regulated during development of tissue-specific extracellular matrices. The role(s) of a leucine-rich repeat protein subfamily in the regulation of Fibrillogenesis during tendon development were defined. Lumican-, fibromodulin-, and double-deficient mice demonstrated disruptions in Fibrillogenesis. With development, the amount of lumican decreases to barely detectable levels while fibromodulin increases significantly, and these changing patterns may regulate this process. Electron microscopic analysis demonstrated structural abnormalities in the fibrils and alterations in the progression through different assembly steps. In lumican-deficient tendons, alterations were observed early and the mature tendon was nearly normal. Fibromodulin-deficient tendons were comparable with the lumican-null in early developmental periods and acquired a severe phenotype by maturation. The double-deficient mice had a phenotype that was additive early and comparable with the fibromodulin-deficient mice at maturation. Therefore, lumican and fibromodulin both influence initial assembly of intermediates and the entry into fibril growth, while fibromodulin facilitates the progression through growth steps leading to mature fibrils. The observed increased ratio of fibromodulin to lumican and a competition for the same binding site could mediate these transitions. These studies indicate that lumican and fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of Fibrillogenesis.
Renato V Iozzo - One of the best experts on this subject based on the ideXlab platform.
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The role of decorin in collagen Fibrillogenesis and skin homeostasis.
Glycoconjugate journal, 2020Co-Authors: Charles C Reed, Renato V IozzoAbstract:Decorin, a prototype member of the growing family of the small leucine-rich proteoglycans (SLRP's), plays significant roles in tissue development and assembly, as well as playing both direct and indirect signaling roles. This review will concentrate on decorin's function in collagen Fibrillogenesis as determined through the study of mice with a disrupted decorin gene. The fragile skin and abnormal tendon phenotypes initially observed were found to be due to fundamental alterations in collagen fibers, highlighting the crucial role of proteoglycans in general and SLRP's in particular in collagen Fibrillogenesis. The altered fibril formation within tissues in turn leads to observable and quantifiable changes at the organismal level. Research into certain fibrotic processes with concomitant upregulation or reduction of decorin makes interesting comparisons with the collagen malformations seen in Dcn(-/-) mice. Overall, decorin is shown to be a vital player in maintaining skin and tendon integrity at the molecular level, among other functions.
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the glycosaminoglycan chain of decorin plays an important role in collagen fibril formation at the early stages of Fibrillogenesis
FEBS Journal, 2007Co-Authors: Claus Ruhland, Elke Schonherr, Horst Robenek, Uwe Hansen, Renato V Iozzo, Peter Bruckner, Daniela G SeidlerAbstract:Decorin is a multifunctional small leucine-rich proteoglycan involved in the regulation of collagen Fibrillogenesis. In patients with a variant of Ehlers–Danlos syndrome, about half of the secreted decorin lacks the single glycosaminoglycan side chain. Notably, these patients have a skin-fragility phenotype that resembles that of decorin null mice. In this study, we investigated the role of glycanated and unglycanated decorin on collagen Fibrillogenesis. Glycosaminoglycan-free decorin, generated by mutating Ser4 of the mature protein core into Ala (DCN-S4A), showed reduced inhibition of Fibrillogenesis compared with the decorin proteoglycan. Interestingly, using a 3D matrix generated by decorin-null fibroblasts, an increase in fibril diameter was found after the addition of decorin, and even greater effects were observed with DCN-S4A. To avoid potential side effects of artificial tags, adenoviruses containing decorin and DCN-S4A were used to transduce decorin-null fibroblasts prior to matrix formation. Both molecules were efficiently incorporated into the matrix, with no changes in collagen composition and network formation, or altered expression of the related proteoglycan biglycan. Both decorin and DCN-S4A mutants increased the collagen fibril diameter, with the latter showing the most prominent effects. These data show that at early stages of Fibrillogenesis, the glycosaminoglycan chain of decorin has a reducing effect on collagen fibril diameter.
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the role of decorin in collagen Fibrillogenesis and skin homeostasis
Glycoconjugate Journal, 2002Co-Authors: Charles C Reed, Renato V IozzoAbstract:Decorin, a prototype member of the growing family of the small leucine-rich proteoglycans (SLRP's), plays significant roles in tissue development and assembly, as well as playing both direct and indirect signaling roles. This review will concentrate on decorin's function in collagen Fibrillogenesis as determined through the study of mice with a disrupted decorin gene. The fragile skin and abnormal tendon phenotypes initially observed were found to be due to fundamental alterations in collagen fibers, highlighting the crucial role of proteoglycans in general and SLRP's in particular in collagen Fibrillogenesis. The altered fibril formation within tissues in turn leads to observable and quantifiable changes at the organismal level. Research into certain fibrotic processes with concomitant upregulation or reduction of decorin makes interesting comparisons with the collagen malformations seen in Dcn−/− mice. Overall, decorin is shown to be a vital player in maintaining skin and tendon integrity at the molecular level, among other functions. Published in 2003.
Aleksey Lomakin - One of the best experts on this subject based on the ideXlab platform.
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amyloid β protein Fibrillogenesis detection of a protofibrillar intermediate
Journal of Biological Chemistry, 1997Co-Authors: Dominic M Walsh, Aleksey Lomakin, George B Benedek, Margaret M Condron, David B TeplowAbstract:Abstract Fibrillogenesis of the amyloid β-protein (Aβ) is a seminal pathogenetic event in Alzheimer’s disease. Inhibiting Fibrillogenesis is thus one approach toward disease therapy. Rational design of Fibrillogenesis inhibitors requires elucidation of the stages and kinetics of Aβ Fibrillogenesis. We report results of studies designed to examine the initial stages of Aβ oligomerization. Size exclusion chromatography, quasielastic light scattering spectroscopy, and electron microscopy were used to characterize Fibrillogenesis intermediates. After dissolution in 0.1 m Tris-HCl, pH 7.4, and removal of pre-existent seeds, Aβ chromatographed almost exclusively as a single peak. The molecules composing the peak had average hydrodynamic radii of 1.8 ± 0.2 nm, consistent with the predicted size of dimeric Aβ. Over time, an additional peak, with a molecular weight >100,000, appeared. This peak contained predominantly curved fibrils, 6–8 nm in diameter and <200 nm in length, which we have termed “protofibrils.” The kinetics of protofibril formation and disappearance are consistent with protofibrils being intermediates in the evolution of amyloid fibers. Protofibrils appeared during the polymerization of Aβ-(1–40), Aβ-(1–42), and Aβ-(1–40)-Gln22, peptides associated with both sporadic and inherited forms of Alzheimer’s disease, suggesting that protofibril formation may be a general phenomenon in Aβ Fibrillogenesis. If so, protofibrils could be attractive targets for Fibrillogenesis inhibitors.
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Amyloid β-Protein Fibrillogenesis DETECTION OF A PROTOFIBRILLAR INTERMEDIATE
Journal of Biological Chemistry, 1997Co-Authors: Dominic M Walsh, Aleksey Lomakin, George B Benedek, Margaret M Condron, David B TeplowAbstract:Abstract Fibrillogenesis of the amyloid β-protein (Aβ) is a seminal pathogenetic event in Alzheimer’s disease. Inhibiting Fibrillogenesis is thus one approach toward disease therapy. Rational design of Fibrillogenesis inhibitors requires elucidation of the stages and kinetics of Aβ Fibrillogenesis. We report results of studies designed to examine the initial stages of Aβ oligomerization. Size exclusion chromatography, quasielastic light scattering spectroscopy, and electron microscopy were used to characterize Fibrillogenesis intermediates. After dissolution in 0.1 m Tris-HCl, pH 7.4, and removal of pre-existent seeds, Aβ chromatographed almost exclusively as a single peak. The molecules composing the peak had average hydrodynamic radii of 1.8 ± 0.2 nm, consistent with the predicted size of dimeric Aβ. Over time, an additional peak, with a molecular weight >100,000, appeared. This peak contained predominantly curved fibrils, 6–8 nm in diameter and
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on the nucleation and growth of amyloid beta protein fibrils detection of nuclei and quantitation of rate constants
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Aleksey Lomakin, George B Benedek, Doo Soo Chung, Daniel A Kirschner, David B TeplowAbstract:We have studied the Fibrillogenesis of synthetic amyloid beta-protein-(1-40) fragment (A beta) in 0.1 M HCl. At low pH, A beta formed fibrils at a rate amenable to detailed monitoring by quasi-elastic light-scattering spectroscopy. Examination of the fibrils with circular dichroism spectroscopy and electron microscopy showed them to be highly similar to those found in amyloid plaques. We determined the hydrodynamic radii of A beta aggregates during the entire process of fibril nucleation and growth. Above an A beta concentration of approximately 0.1 mM, the initial rate of elongation and the final size of fibrils were independent of A beta concentration. Below an A beta concentration of 0.1 mM, the initial elongation rate was proportional to the peptide concentration, and the resulting fibrils were significantly longer than those formed at higher concentration. We also found that the surfactant n-dodecylhexaoxyethylene glycol monoether (C12E6) slowed nucleation and elongation of fibrils in a concentration-dependent manner. Our observations are consistent with a model of A beta Fibrillogenesis that includes the following key steps: (i) peptide micelles form above a certain critical A beta concentration, (ii) fibrils nucleate within these micelles or on heterogeneous nuclei (seeds), and (iii) fibrils grow by irreversible binding of monomers to fibril ends. Interpretation of our data enabled us to determine the sizes of fibril nuclei and A beta micelles and the rates of fibril nucleation (from micelles) and fibril elongation. Our approach provides a powerful means for the quantitative assay of A beta Fibrillogenesis.
Steven S.-s. Wang - One of the best experts on this subject based on the ideXlab platform.
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Exploring the effects of methylene blue on amyloid Fibrillogenesis of lysozyme.
International Journal of Biological Macromolecules, 2018Co-Authors: Yu-hong Cheng, Chun-hsien Lo, Zuzana Bednarikova, Andrea Antosova, Zuzana Gazova, Josephine W. Wu, Steven S.-s. WangAbstract:Abstract The 129-residue lysozyme has been shown to form amyloid fibrils in vitro. While methylene blue (MB), a compound in the phenothiazinium family, has been shown to dissemble tau fibril formation, its anti-fibrillogenic effect has not been thoroughly characterized in other proteins/peptides. This study examines the effects of MB on the in vitro Fibrillogenesis of lysozyme at pH 2.0 and 55 °C. Our results demonstrated that, upon 7-day incubation, the plateau ThT fluorescence of the sample was found to be ~8.69% or ~2.98% of the control when the molar ratio of lysozyme to MB was at 1:1.11 or 1:3.33, respectively, indicating that the inhibitory potency of MB against lysozyme Fibrillogenesis is positively correlated with its concentration. We also found that MB is able to destabilize the preformed lysozyme fibrils. Moreover, molecular docking and molecular dynamics simulations results revealed that MB's mechanism of fibril formation inhibition may be triggered by binding with lysozyme's aggregation-prone region. Results reported here provide solid support for MB's effect on amyloid Fibrillogenesis. We believe the additional insights gained herein may pave way to the discovery of other small molecules that may have similar action toward amyloid fibril formation and its associated diseases.
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Examining the inhibitory actions of copolypeptides against amyloid Fibrillogenesis of bovine insulin
Biochemical Engineering Journal, 2013Co-Authors: Steven S.-s. WangAbstract:Abstract Amyloid Fibrillogenesis has been involved in at least 40 different degenerative diseases. The 51-residue polypeptide hormone insulin, which is associated with type II diabetes, has been demonstrated to fibrillate in vitro. With bovine insulin as a model, the research presented here examines the influence of two simple, unstructured d,l -lysine-co-glycine ( d,l -lys-co-gly) and d,l -lysine-co-L-phenylalanine ( d,l -lys-co-phe) copolypeptides, on the in vitro fibril formation process of bovine insulin at pH 2.0 and 55 °C. Our results showed that amyloid Fibrillogenesis of insulin may be suppressed by both copolypeptides in a concentration-dependent fashion. In addition, the copolypeptides with higher molar fractions of glycine or l -phenylalanine residue, which are considered to possess higher hydrophobic interacting capacities, demonstrated the superior inhibitory potency against insulin fibril formation. Our findings suggest that the association of insulin and copolypeptides, which is likely dominated by hydrophobic interactions and hydrogen bonding, may mitigate the extent of insulin Fibrillogenesis. We believe the results from this work may contribute to the understanding of the molecular factors affecting amyloid fibrillation and the molecular mechanism(s) of the interactions between the unstructured polypeptides and amyloid-forming proteins.
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effect of curcumin on the amyloid Fibrillogenesis of hen egg white lysozyme
Biophysical Chemistry, 2009Co-Authors: Steven S.-s. WangAbstract:Abstract At least twenty human proteins can fold abnormally to form pathological deposits that are associated with several degenerative diseases. Despite extensive investigation on amyloid Fibrillogenesis, its detailed molecular mechanisms remain unknown. This study is aimed at exploring the inhibitory activity of curcumin against the fibrillation of hen lysozyme. We found that the formation of amyloid fibrils at pH 2.0 in vitro was inhibited by curcumin in a dose-dependent manner. Moreover, quenching analysis confirmed the existence of an interaction between curcumin and lysozyme, and Van't Hoff analysis indicated that the curcumin–lysozyme interaction is predominantly governed by Van Der Waals force or hydrogen bonding. Curcumin was also found to acquire disaggregating ability on preformed lysozyme fibrils. Finally, we observed that curcumin pre-incubated at 25 °C for at least 7 days inhibited lysozyme Fibrillogenesis better than untreated curcumin and the enhanced inhibition against HEWL fibrillation might be attributed to the presence of dimeric species.
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Investigating the influences of redox buffer compositions on the amyloid Fibrillogenesis of hen egg-white lysozyme
Biochimica et Biophysica Acta, 2009Co-Authors: Steven S.-s. Wang, Chia-hung WuAbstract:More than twenty different human proteins have been found to fold abnormally resulting in the formation of pathological deposits and several lethal degenerative diseases. Despite extensive investigations on amyloid fibril formation, the detailed molecular mechanism remained rather elusive. The present study is aimed at exploring the effect of the ratio of cysteine and cystine in the buffer on the fibrillation of hen egg-white lysozyme. Our results revealed that the inhibition of lysozyme amyloid formation by cysteine in the redox buffer followed a concentration-dependent fashion. Cystine, the oxidized form of cysteine, nevertheless, did not influence the final level of fibrillation although it lengthened the lag period of fibril formation. Moreover, the effect of the ratio of cysteine to cystine in the buffer on the Fibrillogenesis of hen lysozyme was found to be greatly associated with the formation of mixed disulfide derivatives. Finally, a possible reaction mechanism was proposed to explain our experimental results. Our study shows that the concentration of mixed disulfide derivative was inversely correlated with the level of lysozyme Fibrillogenesis. The results from this work may aid in comprehending the molecular mechanism(s) of amyloid Fibrillogenesis for disulfide bonded proteins and the development of effective therapeutics for amyloidogenic diseases.
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Effect of curcumin on the amyloid Fibrillogenesis of hen egg-white lysozyme.
Biophysical chemistry, 2009Co-Authors: Steven S.-s. WangAbstract:At least twenty human proteins can fold abnormally to form pathological deposits that are associated with several degenerative diseases. Despite extensive investigation on amyloid Fibrillogenesis, its detailed molecular mechanisms remain unknown. This study is aimed at exploring the inhibitory activity of curcumin against the fibrillation of hen lysozyme. We found that the formation of amyloid fibrils at pH 2.0 in vitro was inhibited by curcumin in a dose-dependent manner. Moreover, quenching analysis confirmed the existence of an interaction between curcumin and lysozyme, and Van't Hoff analysis indicated that the curcumin-lysozyme interaction is predominantly governed by Van Der Waals force or hydrogen bonding. Curcumin was also found to acquire disaggregating ability on preformed lysozyme fibrils. Finally, we observed that curcumin pre-incubated at 25 degrees C for at least 7 days inhibited lysozyme Fibrillogenesis better than untreated curcumin and the enhanced inhibition against HEWL fibrillation might be attributed to the presence of dimeric species.