scholarly journals Interaction between Hemin and Prion Peptides: Binding, Oxidative Reactivity and Aggregation

2020 ◽  
Vol 21 (20) ◽  
pp. 7553
Author(s):  
Simone Dell’Acqua ◽  
Elisa Massardi ◽  
Enrico Monzani ◽  
Giuseppe Di Natale ◽  
Enrico Rizzarelli ◽  
...  
Keyword(s):  
Binding Constant ◽  
Prion Diseases ◽  
Amyloid Β ◽  
Binding Constants ◽  
Spectrophotometric Titration ◽  
Moderate Increase ◽  
Oxidative Reactivity ◽  
Long Time ◽  
Uv Visible ◽  
Spin Complex

We investigate the interaction of hemin with four fragments of prion protein (PrP) containing from one to four histidines (PrP106–114, PrP95–114, PrP84–114, PrP76–114) for its potential relevance to prion diseases and possibly traumatic brain injury. The binding properties of hemin-PrP complexes have been evaluated by UV–visible spectrophotometric titration. PrP peptides form a 1:1 adduct with hemin with affinity that increases with the number of histidines and length of the peptide; the following log K1 binding constants have been calculated: 6.48 for PrP76–114, 6.1 for PrP84–114, 4.80 for PrP95–114, whereas for PrP106–114, the interaction is too weak to allow a reliable binding constant calculation. These constants are similar to that of amyloid-β (Aβ) for hemin, and similarly to hemin-Aβ, PrP peptides tend to form a six-coordinated low-spin complex. However, the concomitant aggregation of PrP induced by hemin prevents calculation of the K2 binding constant. The turbidimetry analysis of [hemin-PrP76–114] shows that, once aggregated, this complex is scarcely soluble and undergoes precipitation. Finally, a detailed study of the peroxidase-like activity of [hemin-(PrP)] shows a moderate increase of the reactivity with respect to free hemin, but considering the activity over long time, as for neurodegenerative pathologies, it might contribute to neuronal oxidative stress.

scholarly journals Construction of merged satellite total O<sub>3</sub> and NO<sub>2</sub> time series in the tropics for trend studies and evaluation by comparison to NDACC SAOZ measurements

2014 ◽  
Vol 7 (10) ◽  
pp. 3337-3354 ◽  
Author(s):  
M. Pastel ◽  
J.-P. Pommereau ◽  
F. Goutail ◽  
A. Richter ◽  
A. Pazmiño ◽  
...  
Keyword(s):  
Time Series ◽  
Lower Stratosphere ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Composition Change ◽  
Long Time ◽  
Uv Visible ◽  
The Tropics ◽  
Lower Noise ◽  
Total Column

Abstract. Long time series of ozone and NO2 total column measurements in the southern tropics are available from two ground-based SAOZ (Système d'Analyse par Observation Zénithale) UV-visible spectrometers operated within the Network for the Detection of Atmospheric Composition Change (NDACC) in Bauru (22° S, 49° W) in S-E Brazil since 1995 and Reunion Island (21° S, 55° E) in the S-W Indian Ocean since 1993. Although the stations are located at the same latitude, significant differences are observed in the columns of both species, attributed to differences in tropospheric content and equivalent latitude in the lower stratosphere. These data are used to identify which satellites operating during the same period, are capturing the same features and are thus best suited for building reliable merged time series for trend studies. For ozone, the satellites series best matching SAOZ observations are EP-TOMS (1995–2004) and OMI-TOMS (2005–2011), whereas for NO2, best results are obtained by combining GOME version GDP5 (1996–2003) and SCIAMACHY – IUP (2003–2011), displaying lower noise and seasonality in reference to SAOZ. Both merged data sets are fully consistent with the larger columns of the two species above South America and the seasonality of the differences between the two stations, reported by SAOZ, providing reliable time series for further trend analyses and identification of sources of interannual variability in the future analysis.

scholarly journals Prion protein and prion disease at a glance

2021 ◽  
Vol 134 (17) ◽  
Author(s):  
Caihong Zhu ◽  
Adriano Aguzzi
Keyword(s):  
Prion Protein ◽  
Prion Disease ◽  
Neurodegenerative Disorders ◽  
Prion Diseases ◽  
Amyloid Β ◽  
Cellular Prion Protein ◽  
Future Studies ◽  
Associated Proteins ◽  
Main Component ◽  
Conformational Conversion

ABSTRACT Prion diseases are neurodegenerative disorders caused by conformational conversion of the cellular prion protein (PrPC) into scrapie prion protein (PrPSc). As the main component of prion, PrPSc acts as an infectious template that recruits and converts normal cellular PrPC into its pathogenic, misfolded isoform. Intriguingly, the phenomenon of prionoid, or prion-like, spread has also been observed in many other disease-associated proteins, such as amyloid β (Aβ), tau and α-synuclein. This Cell Science at a Glance and the accompanying poster highlight recently described physiological roles of prion protein and the advanced understanding of pathogenesis of prion disease they have afforded. Importantly, prion protein may also be involved in the pathogenesis of other neurodegenerative disorders such as Alzheimer's and Parkinson's disease. Therapeutic studies of prion disease have also exploited novel strategies to combat these devastating diseases. Future studies on prion protein and prion disease will deepen our understanding of the pathogenesis of a broad spectrum of neurodegenerative conditions.

Apolipoprotein E includes a binding site which is recognized by several amyloidogenic polypeptides

2000 ◽  
Vol 349 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Marc H. BAUMANN ◽  
Jukka KALLIJÄRVI ◽  
Hilkka LANKINEN ◽  
Claudio SOTO ◽  
Matti HALTIA
Keyword(s):  
Apolipoprotein E ◽  
Binding Site ◽  
Late Onset ◽  
Specific Binding ◽  
Prion Diseases ◽  
Amyloid Β ◽  
Structural Motif ◽  
Amyloid Β Peptide ◽  
High Avidity ◽  
Amyloidogenic Protein

Inheritance of the apolipoprotein E (apoE) ϵ4 allele is a risk factor for late-onset Alzheimer's disease (AD). Biochemically apoE is present in AD plaques and neurofibrillary tangles of the AD brain. There is a high avidity and specific binding of apoE and the amyloid β-peptide (Aβ). In addition to AD apoE is also present in many other cerebral and systemic amyloidoses, Down's syndrome and prion diseases but the pathophysiological basis for its presence is still unknown. In the present study we have compared the interaction of apoE with Aβ, the gelsolin-derived amyloid fragment AGel183-210 and the amyloidogenic prion fragments PrP109-122 and PrP109-141. We show that, similar to Aβ, also AGel and PrP fragments can form a complex with apoE, and that the interaction between apoE and the amyloidogenic protein fragments is mediated through the same binding site on apoE. We also show that apoE increases the thioflavin-T fluorescence of PrP and AGel and that apoE influences the content of β-sheet conformation of these amyloidogenic fragments. Our results indicate that amyloids and amyloidogenic prion fragments share a similar structural motif, which is recognized by apoE, possibly through a single binding site, and that this motif is also responsible for the amyloidogenicity of these fragments.

scholarly journals Amyloidogenic Peptides in Human Neuro-Degenerative Diseases and in Microorganisms: A Sorrow Shared Is a Sorrow Halved?

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 925 ◽  
Author(s):  
Kristina Endres
Keyword(s):  
Neurodegenerative Diseases ◽  
Self Assembly ◽  
Amyloid Β ◽  
Degenerative Diseases ◽  
Human Beings ◽  
Precursor Proteins ◽  
Long Time ◽  
Health And Disease ◽  
Amyloidogenic Peptides ◽  
Toxic Peptides

The term “amyloid” refers to proteinaceous deposits of peptides that might be generated from larger precursor proteins e.g., by proteolysis. Common to these peptides is a stable cross-β dominated secondary structure which allows self-assembly, leading to insoluble oligomers and lastly to fibrils. These highly ordered protein aggregates have been, for a long time, mainly associated with human neurodegenerative diseases such as Alzheimer’s disease (Amyloid-β peptides). However, they also exert physiological functions such as in release of deposited hormones in human beings. In the light of the rediscovery of our microbial commensals as important companions in health and disease, the fact that microbes also possess amyloidogenic peptides is intriguing. Transmission of amyloids by iatrogenic means or by consumption of contaminated meat from diseased animals is a well-known fact. What if also our microbial commensals might drive human amyloidosis or suffer from our aggregated amyloids? Moreover, as the microbial amyloids are evolutionarily older, we might learn from these organisms how to cope with the sword of Damocles forged of endogenous, potentially toxic peptides. This review summarizes knowledge about the interplay between human amyloids involved in neurodegenerative diseases and microbial amyloids.

scholarly journals Bifunctional intercalation and sequence specificity in the binding of quinomycin and triostin antibiotics to deoxyribonucleic acid

1978 ◽  
Vol 173 (1) ◽  
pp. 115-128 ◽  
Author(s):  
J S Lee ◽  
M J Waring
Keyword(s):  
Binding Constant ◽  
Binding Constants ◽  
Sequence Specificity ◽  
Peptide Antibiotics ◽  
Naturally Occurring ◽  
Binding Isotherms ◽  
Triostin A ◽  
Specificity Pattern ◽  
Intercalating Agents ◽  
Binding Curves

Quinomycin C, triostin A and triostin C are peptide antibiotics of the quinoxaline family, of which echinomycin (quinomycin A) is also a member. They all remove and reverse the supercoiling of closed circular duplex DNA from bacteriophage PM2 in the fashion characteristic of intercalating drugs, and the unwinding angle at I 0.01 is, in all cases, almost twice that of ethidium. Thus, as with echinomycin, they can be characterized as bifunctional intercalating agents. For the triostins this conclusion has been confirmed by measurements of changes in the viscosity of sonicated rod-like DNA fragments; the helix extension was found to be almost double that expected for a simple monofunctional intercalation process. For triostin A, further evidence for bifunctionality was derived from the cross-over point of binding isotherms to nicked circular and closed circular bacteriophage-PM2DNA. Binding curves for the interaction of quinomycin C and triostin A with a variety of synthetic and naturally occurring nucleic acids were determined by solvent-partition analysis, but triostin C was too insoluble in aqueous solution to make this method applicable. For quinomycin C the highest binding constant was found with Micrococcus lysodeikticus DNA, and its pattern of specificity among natural DNA species was broadly similar to that of echinomycin, although the binding constants were 2–6 times as large. For triostin A the highest binding constant was again found for M. lysodeikticus DNA, but the specificity pattern was quite different from that of the quinomycins. In particular, triostin A bound better to poly(dA-dT) than to the poly(dG-dC) whereas this order was reversed for quinomycin C. There was also evidence that the binding to poly(dA-dT) might be co-operative in nature. No significant interaction could be detected with poly(dA).poly(dT) or with RNA from Escherichia coli. Poly(dG).poly(dC) gave variable results, depending on the source of the polymer. The different patterns of specificity displayed by the quinomycins and triostins are tentatively ascribed to differences in their conformations in solution.

Host-guest interactions of cyclodextrins and metalloporphyrins: supramolecular building blocks toward artificial heme proteins

2004 ◽  
Vol 08 (02) ◽  
pp. 125-140 ◽  
Author(s):  
Huchen Zhou ◽  
John T. Groves
Keyword(s):  
Binding Constant ◽  
Molecular Design ◽  
Covalent Binding ◽  
Binding Constants ◽  
Building Blocks ◽  
Binding Pocket ◽  
Axial Ligand ◽  
Pyridyl Nitrogen ◽  
H Nmr ◽  
Self Assembled

Cyclodextrins are versatile building blocks for a variety of macromolecules due to the inclusion complexes that are formed with hydrophobic organic molecules. Cyclodextrin-porphyrin interactions are of particular interest since cyclodextrins can serve as a non-covalent binding pocket while metalloporphyrins could serve as the heme analogs in the construction of heme protein model compounds. Various approaches to the design and assembly of biomimetic porphyrin constructs are compared and contrasted in this minireview with a particular emphasis on self-assembled and porphyrin-cyclodextrin systems. Several recent advances from our laboratories are described in this context. A sensitive fluorescent binding probe, 6A-N-dansyl-permethylated-β-cyclodextrin (Dan-NH-TMCD), was found to form 2:1 complexes with the meso-tetraphenylporphyrins Mn(III)TCPP , Mn(III)TPPS and Mn(III)TF 4 TMAP with high binding constants. A perPEGylated cyclodextrin, heptakis(2,3,6-tri-O-2-(2-(2-methoxyethoxy)ethoxy)ethyl)-β-cyclodextrin (TPCD), has been shown by 1 H NMR spectroscopy to form a 1:1 complex with H 2 TCPP with a binding constant above 108M-1. Such a strong binding constant is the largest found for a 1:1 complex between a monomeric cyclodextrin and a guest. TPCD was also found to bind Mn(III)TCPP with a binding constant of 1.2 × 106 M -1. A novel, self-assembled hemoprotein model, hemodextrin is also described. The molecular design is based on a PEGylated cyclodextrin scaffold that bears both a heme-binding pocket and an axial ligand that binds an iron porphyrin. The binding constant for Fe (III) TPPS (iron(III) meso-tetra(4-sulfonatophenyl)porphyrin) by py-PPCD was determined to be 2 × 106 M -1. The pyridyl nitrogen of py-PPCD was shown to ligate to the iron center by observing signal changes in the Fe(II) -porphyrin 1 H NMR spectrum. This hemodextrin ensemble, a minimalist myoglobin, was shown to bind dioxygen reversibly and to form a stable ferryl species.

scholarly journals Link between Affinity and Cu(II) Binding Sites to Amyloid-β Peptides Evaluated by a New Water-Soluble UV–Visible Ratiometric Dye with a Moderate Cu(II) Affinity

2017 ◽  
Vol 89 (3) ◽  
pp. 2155-2162 ◽  
Author(s):  
Amandine Conte-Daban ◽  
Valentina Borghesani ◽  
Stéphanie Sayen ◽  
Emmanuel Guillon ◽  
Yves Journaux ◽  
...  
Keyword(s):  
Binding Sites ◽  
Amyloid Β ◽  
Water Soluble ◽  
Uv Visible

scholarly journals Attempt to Untangle the Prion-Like Misfolding Mechanism for Neurodegenerative Diseases

2018 ◽  
Vol 19 (10) ◽  
pp. 3081 ◽  
Author(s):  
Daniela Sarnataro
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Lipid Membrane ◽  
Prion Diseases ◽  
Amyloid Β ◽  
Phosphatidyl Inositol ◽  
Cellular Prion Protein ◽  
Endoplasmic Reticulum Quality Control ◽  
Endogenous Proteins ◽  
Membrane Components

The misfolding and aggregation of proteins is the neuropathological hallmark for numerous diseases including Alzheimer’s disease, Parkinson’s disease, and prion diseases. It is believed that misfolded and abnormal β-sheets forms of wild-type proteins are the vectors of these diseases by acting as seeds for the aggregation of endogenous proteins. Cellular prion protein (PrPC) is a glycosyl-phosphatidyl-inositol (GPI) anchored glycoprotein that is able to misfold to a pathogenic isoform PrPSc, the causative agent of prion diseases which present as sporadic, dominantly inherited and transmissible infectious disorders. Increasing evidence highlights the importance of prion-like seeding as a mechanism for pathological spread in Alzheimer’s disease and Tauopathy, as well as other neurodegenerative disorders. Here, we report the latest findings on the mechanisms controlling protein folding, focusing on the ER (Endoplasmic Reticulum) quality control of GPI-anchored proteins and describe the “prion-like” properties of amyloid-β and tau assemblies. Furthermore, we highlight the importance of pathogenic assemblies interaction with protein and lipid membrane components and their implications in both prion and Alzheimer’s diseases

Binding constants for tetramethylammonium ion determined with irreversible inhibitors of acetylcholinesterase

1976 ◽  
Vol 54 (10) ◽  
pp. 918-920 ◽  
Author(s):  
F. Iverson
Keyword(s):  
Rate Constant ◽  
Binding Constant ◽  
Binding Constants ◽  
Single Site ◽  
Reversible Binding ◽  
Bimolecular Rate Constant ◽  
Irreversible Inhibitors ◽  
Carbamate Inhibitors

The reversible binding constant (Ki) for tetramethylammonium ion (TMA) was determined from the decrease in the bimolecular rate constant (ki) observed with each of 21 organophosphate or carbamate inhibitors of acetylcholinesterase (EC 3.1.1.7). The Ki values obtained were reasonably constant (5.8 × 10−4 ± 0.38 M), and this is consistent with reports indicating that TMA binds to a single site on the enzyme.

The use of β-cyclodextrins to enhance the aqueous solubility of trichloroethylene and perchloroethylene and their removal from soil organic matter: Effect of substituents

2003 ◽  
Vol 81 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Salma Shirin ◽  
Erwin Buncel ◽  
Gary W vanLoon
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Binding Constant ◽  
Binding Constants ◽  
Aqueous Solubility ◽  
Solubility Enhancement ◽  
Degree Of Substitution ◽  
Water Remediation ◽  
Effective Removal ◽  
Matter Effect

This paper describes a systematic study for the evaluation of different substituted β-cyclodextrins (β-CDs), as agents for the enhancement of the aqueous solubility of two major organic pollutants, trichloroethylene (TCE) and perchloroethylene (PCE). The aqueous solubility enhancement occurs through the formation of host–guest inclusion complexes between the CD molecule (host) and the polychloroethylene (guest) and is driven primarily by hydrophobic forces. The CDs evaluated are: methyl-β-CD (Mβ-CD), hydroxypropyl-β-CD (HPβ-CD), carboxymethyl-β-CD (CMβ-CD1, CMβ-CD2), and sulfated-β-CD (Sβ-CD1, Sβ-CD2); the degree of substitution was also varied. Using a 5% (w/v) aqueous CD solution, solubility enhancement factors (St/So) up to 5.5 and 14 were determined for TCE and PCE, respectively. Binding constants (K11) for TCE with the substituted CDs were evaluated using an 1H NMR technique; these were found to range from 3 to 120 M–1. It was shown that solubility enhancement, as well as the binding constant, is dependent on the type and degree of substitution of the β-CD molecule; the determining factors are discussed. The CDs are also capable of effective removal of PCE and TCE retained by soil organic matter. Thus, a suitably substituted β-CD may be a valuable additive in pump-and-treat protocols for site remediation of polychlorinated organics. Key words: Cyclodextrin, trichloroethylene, perchloroethylene, solubility enhancement, binding constant, soil and water remediation.

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