Structurally Distinct External Solvent-Exposed Domains Drive Replication of Major Human Prions

There is a limited understanding of structural attributes that encode the iatrogenic transmissibility and various phenotypes of prions causing the most common human prion disease, sporadic Creutzfeldt-Jakob disease (sCJD). Here we report the detailed structural differences between major sCJD MM1, MM2, and VV2 prions determined with two complementary synchrotron hydroxyl radical footprinting techniques—mass spectrometry (MS) and conformation dependent immunoassay (CDI) with a panel of Europium-labeled antibodies. Both approaches clearly demonstrate that the phenotypically distant prions differ in a major way with regard to their structural organization, and synchrotron-generated hydroxyl radicals progressively inhibit their seeding potency in a strain and structure-specific manner. Moreover, the seeding rate of sCJD prions is primarily determined by strain-specific structural organization of solvent-exposed external domains of human prion particles that control the seeding activity. Structural characteristics of human prion strains suggest that subtle changes in the organization of surface domains play a critical role as a determinant of human prion infectivity, propagation rate, and targeting of specific brain structures

Populations of Tau Conformers Drive Prion-like Strain Effects in Alzheimer’s Disease and Related Dementias

Recent findings of diverse populations of prion-like conformers of misfolded tau protein expand the prion concept to Alzheimer’s disease (AD) and monogenic frontotemporal lobar degeneration (FTLD)-MAPT P301L, and suggest that distinct strains of misfolded proteins drive the phenotypes and progression rates in many neurodegenerative diseases. Notable progress in the previous decades has generated many lines of proof arguing that yeast, fungal, and mammalian prions determine heritable as well as infectious traits. The extraordinary phenotypic diversity of human prion diseases arises from structurally distinct prion strains that target, at different progression speeds, variable brain structures and cells. Although human prion research presents beneficial lessons and methods to study the mechanism of strain diversity of protein-only pathogens, the fundamental molecular mechanism by which tau conformers are formed and replicate in diverse tauopathies is still poorly understood. In this review, we summarize up to date advances in identification of diverse tau conformers through biophysical and cellular experimental paradigms, and the impact of heterogeneity of pathological tau strains on personalized structure- and strain-specific therapeutic approaches in major tauopathies

Molecular Docking of Aβ\u3csub\u3e1–40\u3c/sub\u3e Peptide and Its Iowa D\u3csub\u3e23\u3c/sub\u3eN Mutant Using Small Molecule Inhibitors: Possible Mechanisms of Aβ-peptide Inhibition

Alzheimer\u27s disease (AD) is the most common form of neurodegenerative diseases, characterized by the deposition of Aβ (amyloid beta) peptide. In this study, we have unravelled the interactions as well as anti amyloidogenic behaviour of 40 small molecule inhibitors with Aβ1–40 peptide and Iowa mutant D23N-Aβ115–42 peptide at atomic level and their modes of binding by docking approaches. The binding mode between wild type peptide and drug is distinctly different from the Iowa-mutant-peptide and drug. Here we proposed possible mechanisms of amyloid beta peptide inhibition by small molecule and prevent monomer-monomer interactions via at least three different mechanisms. In the first mechanism, four catechins efficiently interacted with the C-terminal region of peptides through hydrogen bonds and inhibited the peptides. This may lead to blockage of access of second molecule of Aβ-peptide. Secondly, in the case Iowa mutant D23N-Aβ15–42 peptide, same catechin form hydrogen bond with the important mutated Asn23 residue which acts as hydrogen bond donor and acceptor leading to tight binding of inhibitor with the peptide and may prevent monomer-monomer interactions. The third mechanism relies on the ability of drug molecules to mask hydrophobic residues of the peptide, thereby possibly inhibiting hydrophobic interactions between the two beta peptides

Chickpea Peptide: A Nutraceutical Molecule Corroborating Neurodegenerative and ACE-I Inhibition

Chickpea seeds are the source of proteins in human nutrition and attribute some nutraceutical properties. Herein, we report the effects of chickpea seed bioactive peptide on albumin, insulin, lactoglobulin and lysozyme amyloid fibril formation. Employing thioflavin T (ThT) assays and circular dichroism (CD), amyloid structural binding transition was experimented to analyze the inhibition of amyloid fibril formation. The purified active peptide with a molecular mass of 934.53 Da was evaluated in vitro for its ACE-I inhibitory, antibacterial, antifungal and antidiabetic activities. Further, in vivo animal studies were carried out in wistar rats for blood pressure lowering action. In hypertensive rats, chickpea peptide decreased 131 ± 3.57 mm of Hg for systolic blood pressure and 86 ± 1.5 mm of Hg for diastolic blood pressure after 8 h intraperitoneal administration. Additionally, the peptide suppressed the fibrillation of amyloid and destabilized the preformed mature fibrils. Data emphasize efficacy of chickpea peptide vis-a-vis ACE-Inhibitory, antibacterial, antifungal, antidiabetic and anti-amyloidogenic activities, allowing us to propose this novel peptide as a suitable candidate for nutraceutical-based drugs and seems the first kind of its nature

Correction: A Comprehensive Spectroscopic and Computational Investigation to Probe the Interaction of Antineoplastic Drug Nordihydroguaiaretic Acid with Serum Albumins.

[This corrects the article DOI: 10.1371/journal.pone.0158833.]

Binding interaction of four azo linked copper (II) complexes with Human Serum Albumin (HSA): Spectroscopic and molecular docking explorations

Four copper (II) complexes [Cu(L1)2] (1), [Cu(L2)2] (2), [Cu(L3)2] (3) and [Cu(L4)2] (4) with azo linked O,O donar ligands viz 2-hydroxy-5 (phenyldiazenyl)benzaldehyde (HL1), 1-(2-hydroxy-5-(phenyldiazenyl)phenyl)ethanone (HL2), 2-Hydroxy-5-p-tolylazo-benzaldehyde (HL3), 1-(2-Hydroxy-5-p-tolylazo-phenyl)-ethanone (HL4) have been prepared and characterized by different spectroscopy methods and published earlier by our research group. We investigated the interaction of Human Serum Albumin (HSA) with complexes 1–4 under physiological condition in phosphate buffer solution at pH 7.4 using various spectroscopic techniques. The fluorescence titration spectrum disclosed that the complex 1–4 quench the intrinsic fluorescence of HSA robustly through a static quenching mechanism. Binding constants (Kb) and the number of binding sites (n ≈ 1) were evaluated using modified Stern–Volmer equations. Binding constants were found to be 1.9, 6.6, 0.99 and 1.2x 105 (M−1) for complex 1, 2, 3 and 4 respectively. The CD spectra of free HSA and HSA with complexes 1–4 showed that the complexes have negligibleimpact on the secondary structure of HSA as theyremain helical even after the addition of complexes. Molecular docking study was performed to analyse the binding mode of complexes 1-4with HSA. Docking study revealed that hydrophobic and Vander waals interactions were considered to be the main interaction forces involved in the binding of HSA with complexes 1–4

A Comprehensive Spectroscopic and Computational Investigation to Probe the Interaction of Antineoplastic Drug Nordihydroguaiaretic Acid with Serum Albumins - Fig 5

<p>Absorption spectra of HSA (A) and BSA (B) gradually titrated with NDGA upto 1:10 molar ratio of albumins to NDGA, at 37°C.</p

Molecular Basis of the Inhibition and Disaggregation of Thermally-induced Amyloid Fibrils of Human Serum Albumin by an Anti-Parkinson\u27s Drug, Benserazide Hydrochloride

This study summarises the results of multifactorial analysis of the inhibition/destabilization of human serum albumin (HSA) amyloid fibrils by an anti-Parkinson\u27s drug, benserazide hydrochloride (BH). Different biophysical techniques have been utilized for this purpose. Rayleigh light scattering (RLS) and dynamic light scattering (DLS) confirmed the formation of aggregates, that were identified as amyloid fibrils by the thioflavin T (ThT) and Congo Red (CR) fluorescent dye binding assays. Formation of amyloid fibrils and their inhibition/disaggregation was further characterized by transmission electron microscopy (TEM). The cytoprotective role of BH was examined by cytotoxicity assay performed on the SH-SY5Y neuronal cells. The deviation from linearity in the Stern Volmer plot indicated the presence of static and dynamic quenching of the HSA intrinsic fluorescence by BH. The value of Kd obtained by Scatchard plot was 4.5 × 10−4 M. The changes in the Trp microenvironment caused by the BH binding were further characterized by the synchronous fluorescence spectroscopy. Circular dichroism (CD) and differential scanning calorimetry (DSC) indicated increased HSA stability when bound to BH. Multiple binding sites in human serum albumin (HSA) for BH were found by binding and docking analysis, which revealed the involvement of hydrophobic and hydrogen bonding in the HSA-BH complex formation. Further, the negativity of the binding free energy suggested the spontaneity of the BH-HSA interaction. Overall, our study indicated that BH can serve as an efficient inhibitor/destabilizer of amyloid fibrils and the possible mechanism of this efficiency includes stabilization of HSA in the presence of BH. Therefore, BH can be used in treatment of systemic amyloidoses, since this drug cannot cross blood brain barrier (BBB)