Spectroscopic characterization of conformational differences between PrP C and PrP Sc : an α-helix to β-sheet transition

1994 ◽  
Vol 343 (1306) ◽  
pp. 435-441 ◽  
Keyword(s):  
Synthetic Peptides ◽  
Conformational Transition ◽  
Prion Diseases ◽  
Limited Proteolysis ◽  
Spectroscopic Characterization ◽  
Cellular Prion Protein ◽  
Α Helix ◽  
And Shifts ◽  
Β Sheet

Although no chemical modifications have been found to distinguish the cellular prion protein PrP c from its infectious analogue PrP Sc , spectroscopic methods such as Fourier transform infrared (ftir) spectroscopy reveal a major conformational difference. PrP c is rich in a-helix but is devoid of β-sheet,whereas PrP Sc is high in β-sheet. N-terminal truncation of PrP Sc by limited proteolysis does not destroy infectivity but it increases the β-sheet content and shifts the ftir absorption to lower frequencies, typical of the cross β-pleated sheets of amyloids. Thus the formation of PrP Sc from PrP c involves a conformational transition in which one or more x-helical regions of the protein is converted to β-sheet. This transition is mimicked by synthetic peptides, allowing predictions of domains of PrP involved in prion diseases.

13C CP/MAS NMR Spectroscopic Characterization of Native Silk Fibers

2011 ◽  
Vol 175-176 ◽  
pp. 328-332 ◽  
Author(s):  
Wei Zhang ◽  
Jian Xin He ◽  
Yan Wang
Keyword(s):  
13C Nmr Spectroscopy ◽  
Spectroscopic Characterization ◽  
Random Coil ◽  
Silk Fibers ◽  
Significant Difference ◽  
Sheet Structure ◽  
Α Helix ◽  
Cp Mas Nmr ◽  
Β Sheet

Differences in secondary structure among Bombyx mori (B. mori) silk and two wild silks of Antheraea yamamai (A. yamamai) and Antheraea pernyi (A. pernyi) were investigated by CP/MAS 13C NMR Spectroscopy. The β-sheet structure was primary in three silk, and B. mori silk had the highest β-sheet structure. Although amino acid compositions are very similar for two wild silk, their secondary structures had significant difference. A. yamamai silk contained more α-helix structure, whereas more β-turn and random coil structures formed in A. pernyi silk. B. mori silk was mainly composed of anti-parallel β-sheet structure, however, the parallel β-sheet structure was advantage in the two wild silks, and A. yamamai silk contained more anti-parallel β-sheet conformation than A. pernyi silk.

Influence of Post-Treatment with Methanol Vapor on the Properties of SF/P(LLA-CL) Nanofibrous Scaffolds

2011 ◽  
Vol 236-238 ◽  
pp. 2221-2224
Author(s):  
Kui Hua Zhang ◽  
Xiu Mei Mo
Keyword(s):  
Electrospun Nanofibers ◽  
Random Coil ◽  
Methanol Vapor ◽  
Nanofibrous Scaffolds ◽  
Nanofibrous Structure ◽  
Α Helix ◽  
Β Sheet ◽  
Ideal Method ◽  
C Nmr

In order to improve water-resistant ability silk fibroin (SF) and SF/P(LLA-CL) blended nanofibrous scaffolds for tissue engineering applications, methanol vapor were used to treat electrospun nanofibers. SEM indicated SF and SF/ P(LLA-CL) scaffolds maintained nanofibrous structure after treated with methanol vapor and possessed good water-resistant ability. Characterization of 13C NMR clarified methanol vapor induced SF conformation from random coil or α- helix to β-sheet. Moreover, treated SF/ P (LLA-CL) nanofibrous scaffolds still kept good mechanical properties. Methanol vapor could be ideal method to treat SF and SF/ P(LLA-CL) nanofibrous scaffolds for biomedical applications.

scholarly journals Dimerization of the cellular prion protein inhibits propagation of scrapie prions

2018 ◽  
Vol 293 (21) ◽  
pp. 8020-8031 ◽  
Author(s):  
Anna D. Engelke ◽  
Anika Gonsberg ◽  
Simrika Thapa ◽  
Sebastian Jung ◽  
Sarah Ulbrich ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Prion Protein ◽  
Conformational Transition ◽  
Prion Diseases ◽  
Neuroblastoma Cells ◽  
Direct Interaction ◽  
Cellular Prion Protein ◽  
Dominant Negative ◽  
Dimerization Domain ◽  
Hydrophobic Domain

A central step in the pathogenesis of prion diseases is the conformational transition of the cellular prion protein (PrPC) into the scrapie isoform, denoted PrPSc. Studies in transgenic mice have indicated that this conversion requires a direct interaction between PrPC and PrPSc; however, insights into the underlying mechanisms are still missing. Interestingly, only a subfraction of PrPC is converted in scrapie-infected cells, suggesting that not all PrPC species are suitable substrates for the conversion. On the basis of the observation that PrPC can form homodimers under physiological conditions with the internal hydrophobic domain (HD) serving as a putative dimerization domain, we wondered whether PrP dimerization is involved in the formation of neurotoxic and/or infectious PrP conformers. Here, we analyzed the possible impact on dimerization of pathogenic mutations in the HD that induce a spontaneous neurodegenerative disease in transgenic mice. Similarly to wildtype (WT) PrPC, the neurotoxic variant PrP(AV3) formed homodimers as well as heterodimers with WTPrPC. Notably, forced PrP dimerization via an intermolecular disulfide bond did not interfere with its maturation and intracellular trafficking. Covalently linked PrP dimers were complex glycosylated, GPI-anchored, and sorted to the outer leaflet of the plasma membrane. However, forced PrPC dimerization completely blocked its conversion into PrPSc in chronically scrapie-infected mouse neuroblastoma cells. Moreover, PrPC dimers had a dominant-negative inhibition effect on the conversion of monomeric PrPC. Our findings suggest that PrPC monomers are the major substrates for PrPSc propagation and that it may be possible to halt prion formation by stabilizing PrPC dimers.

scholarly journals Synthetic Dimeric Aβ(28–40) Mimics the Complex Epitope of Human Anti-Aβ Autoantibodies against Toxic Aβ Oligomers

2013 ◽  
Vol 288 (38) ◽  
pp. 27638-27645 ◽  
Author(s):  
Andreas M. Roeder ◽  
Yvonne Roettger ◽  
Anne Stündel ◽  
Richard Dodel ◽  
Armin Geyer
Keyword(s):  
Conformational Transition ◽  
Amyloid Peptide ◽  
Cd Spectra ◽  
Aβ Oligomers ◽  
Peptide Epitopes ◽  
Β Amyloid ◽  
Covalently Linked ◽  
Β Amyloid Peptide ◽  
Α Helix ◽  
Β Sheet

Covalently linked carboxyl-terminal segments of the β-amyloid peptide (Aβ) were tested for their qualification as minimal conformational epitopes of the naturally occurring human autoantibodies against β-amyloid (nAbs-Aβ). nAbs-Aβ specifically recognize the toxic oligomers of Aβ and not the monomeric or the fibrillar forms of Aβ. The synthetic dimers of Aβ(28–40) described herein mimic the toxic Aβ oligomers but are not kinetic intermediates with uncertain compositions. CD spectra identified a surprisingly rich conformational behavior of selected miniamyloids. We observed a highly cooperative conformational transition of β-sheet to α-helix upon the addition of the helix enforcing co-solvent hexafluoroisopropanol. The CD curves of dimer 9 resembled, in a completely reversible manner, the CD spectra measured during the irreversible fibrillation of the parent Aβ(1–40). Synthetic peptide epitopes with high affinities for nAbs-Aβ are needed to identify the physiological roles of nAbs-Aβ and are promising epitopes for vaccination experiments.

scholarly journals Calculation and Analysis of Fractal Descriptors for Protein Amino Acids in Various Conformational States

2018 ◽  
Vol 1 (3) ◽  
pp. e00070
Author(s):  
V.Yu. Grigorev ◽  
L.D. Grigoreva
Keyword(s):  
Amino Acids ◽  
Conformational Transition ◽  
Van Der Waals ◽  
Conformational State ◽  
Conformational States ◽  
Protein Amino Acids ◽  
Α Helix ◽  
Β Sheet ◽  
Fractal Descriptor

A series of 20 proteinogenic amino acids was studied. Four types of fractal descriptors for 2 conformational states are calculated: α-helix and 1-strand β-sheet. Based on the analysis of the results obtained, it is established that when the conformational state of the amino acids (α-helix→β-sheet) changes, significant changes in the fractal descriptor Dtot, in the calculation of which all the atoms of the molecule are used, are not observed. However, the more specific descriptors Dval, Dvdw and Dunb, which reflect the aggregate of valence-coupled, van der Waals contact and unbound atoms, respectively, are more sensitive to the conformational transition. The increase Dval, Dvdw and the decrease Dunb values were established for a series of 7 amino acids.

Raman Spectroscopic Investigation of the Denaturation Process of Silk Fibroin

1989 ◽  
Vol 43 (7) ◽  
pp. 1269-1272 ◽  
Author(s):  
Siding Zheng ◽  
Guanxian Li ◽  
Wenhuo Yao ◽  
Tongyin Yu
Keyword(s):  
Raman Spectroscopy ◽  
Silk Fibroin ◽  
Conformational Transition ◽  
Transition Process ◽  
Random Coil ◽  
Helical Conformation ◽  
Extension Rate ◽  
Α Helix ◽  
Β Sheet ◽  
Denaturation Process

The mechanical denaturation process of silk fibroin is examined by Raman spectroscopy. The fresh silk fibroins from the middle gland of mature silkworms are drawn to various ratios on a tensile tester ( R = ldrawn/ linitial, where l is length) and their conformations are measured with Raman spectroscopy. Undrawn silk fibroin is mainly in the random coil structure with some α-helical conformation, the characteristic bands appearing at 1252 and 1660 (random coil) and at 942, 1106, and 1270 cm−1 (α-helix). When the samples are drawn up to R = 4 at an extension rate of 500 mm/min, two peaks at 1233 cm−1 (the amide III band) and 1085 cm−1 appear; it is shown that the β-sheet conformation is then formed. With an increase in drawing ratios, the intensities of these β-sheet bands increase and those of the random coil and α-helical bands decrease gradually. These changes indicate that, under the action of stress, the conformation of fibroin is altered from random coil and α-helix to β-sheet structures. This result is quite similar to the results achieved by the spinning of the silkworm. The effect of the water content in liquid silk on this conformational transition process is revealed and discussed.

scholarly journals Thermal, chemical and chemothermal denaturation of yeast enolase

2003 ◽  
Vol 17 (2-3) ◽  
pp. 453-467 ◽  
Author(s):  
Ping Huang ◽  
Aichun Dong
Keyword(s):  
Fourier Transform ◽  
Thermal Denaturation ◽  
Conformational Transition ◽  
Denaturant Concentration ◽  
Unfolded State ◽  
Random Structures ◽  
Α Helix ◽  
Heterogeneous Ensemble ◽  
Β Sheet ◽  
Yeast Enolase

We studied the temperature‒ and denaturant‒induced denaturation of yeast enolase by means of Fourier transform infrared spectroscopy. The temperature‒induced denaturation/aggregation of the enzyme in the absence of denaturant was highly cooperative and occurred between 55 and 65°C with a midpoint of ~58°C. Above 55°C, the intensity at 1656 cm−1(predominantly α‒helix) decreases as a function of temperature, accompanied by the appearance of two new bands at 1622 and 1696 cm−1, indicating the formation of intermolecular β‒sheet aggregates. Five clearly defined isosbestic points were observed, indicating a two‒state conformational transition. Addition of a non‒denaturing concentration of gdnHCl (0.4 M) caused the thermal denaturation/aggregation of the enzyme to proceed faster, but this revealed no unfolding intermediate. The gdnHCl‒induced unfolding was first detected at a gdnHCl concentration of above 0.4 M, evidenced by loss of α‒helix and β‒sheet structures as functions of denaturant concentration. The fully unfolded state was reached at a gdnHCl concentration of 1.6 M. A significant amount of intermolecular β‒sheet aggregate was detected at gdnHCl concentrations between 0.6 and 1.0 M, which disappeared as the denaturant concentration increased further. The gdnHCl‒unfolded state is a heterogeneous ensemble of turns, helix/loops, and random structures, which continues to change at higher concentrations of denaturant.

scholarly journals Conversion of alpha-helices into beta-sheets features in the formation of the scrapie prion proteins

1993 ◽  
Vol 90 (23) ◽  
pp. 10962-10966 ◽  
Author(s):  
K M Pan ◽  
M Baldwin ◽  
J Nguyen ◽  
M Gasset ◽  
A Serban ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Prion Protein ◽  
Conformational Transition ◽  
Prion Proteins ◽  
Limited Proteolysis ◽  
Alpha Helix ◽  
Beta Sheets ◽  
Cellular Prion Protein ◽  
Beta Sheet ◽  
Alpha Helices

Prions are composed largely, if not entirely, of prion protein (PrPSc in the case of scrapie). Although the formation of PrPSc from the cellular prion protein (PrPC) is a post-translational process, no candidate chemical modification was identified, suggesting that a conformational change features in PrPSc synthesis. To assess this possibility, we purified both PrPC and PrPSc by using nondenaturing procedures and determined the secondary structure of each. Fourier-transform infrared (FTIR) spectroscopy demonstrated that PrPC has a high alpha-helix content (42%) and no beta-sheet (3%), findings that were confirmed by circular dichroism measurements. In contrast, the beta-sheet content of PrPSc was 43% and the alpha-helix 30% as measured by FTIR. As determined in earlier studies, N-terminally truncated PrPSc derived by limited proteolysis, designated PrP 27-30, has an even higher beta-sheet content (54%) and a lower alpha-helix content (21%). Neither PrPC nor PrPSc formed aggregates detectable by electron microscopy, while PrP 27-30 polymerized into rod-shaped amyloids. While the foregoing findings argue that the conversion of alpha-helices into beta-sheets underlies the formation of PrPSc, we cannot eliminate the possibility that an undetected chemical modification of a small fraction of PrPSc initiates this process. Since PrPSc seems to be the only component of the "infectious" prion particle, it is likely that this conformational transition is a fundamental event in the propagation of prions.

scholarly journals Expanding spectrum of prion diseases

2020 ◽  
Vol 4 (2) ◽  
pp. 155-167
Author(s):  
Jacob I. Ayers ◽  
Nick A. Paras ◽  
Stanley B. Prusiner
Keyword(s):  
Amino Acids ◽  
Nucleic Acid ◽  
Prion Protein ◽  
Prion Diseases ◽  
Lewy Body Dementia ◽  
Cellular Prion Protein ◽  
Chromosomal Gene ◽  
Scrapie Agent ◽  
Β Sheet ◽  
Translational Process

Prions were initially discovered in studies of scrapie, a transmissible neurodegenerative disease (ND) of sheep and goats thought to be caused by slow viruses. Once scrapie was transmitted to rodents, it was discovered that the scrapie pathogen resisted inactivation by procedures that modify nucleic acids. Eventually, this novel pathogen proved to be a protein of 209 amino acids, which is encoded by a chromosomal gene. After the absence of a nucleic acid within the scrapie agent was established, the mechanism of infectivity posed a conundrum and eliminated a hypothetical virus. Subsequently, the infectious scrapie prion protein (PrPSc) enriched for β-sheet was found to be generated from the cellular prion protein (PrPC) that is predominantly α-helical. The post-translational process that features in nascent prion formation involves a templated conformational change in PrPC that results in an infectious copy of PrPSc. Thus, prions are proteins that adopt alternative conformations, which are self-propagating and found in organisms ranging from yeast to humans. Prions have been found in both Alzheimer's (AD) and Parkinson's (PD) diseases. Mutations in APP and α-synuclein genes have been shown to cause familial AD and PD. Recently, AD was found to be a double prion disorder: both Aβ and tau prions feature in this ND. Increasing evidence argues for α-synuclein prions as the cause of PD, multiple system atrophy, and Lewy body dementia.

Cloning and Characterization of Three Genes Encoding LMW-GSs from Triticum aestivum, Cultival Cheyenne

2012 ◽  
Vol 554-556 ◽  
pp. 1116-1120 ◽  
Author(s):  
Mei Rong Chen ◽  
Xing Shen ◽  
Lin Li ◽  
Song Qing Hu
Keyword(s):  
Amino Acid ◽  
Structure Prediction ◽  
Secondary Structure Prediction ◽  
Amino Acid Residues ◽  
Repetitive Domain ◽  
Genebank Accession ◽  
Genes Encoding ◽  
Α Helix ◽  
Β Sheet

Three low molecular weight subunit genes, named LMW-CND1 (GeneBank accession JQ780048), LMW-CND2 (GeneBank accession JQ779840), LMW-CND3 (GeneBank accession JQ779841), with a ORF of 1053 bp, 903 bp, 969 bp, respectively, were isolated from cv. Cheyenne and characterized detailed in molecular level. The proteins encoded by the genes, with 350, 300, 322 amino acid residues respectively, differ only in repetitive domain of sequences due to insertion or deletion of repeats in this domain. Highly similarity in amino-acid sequence between these three subunits and other published LMW-GSs was also observed, showing that all three genes published here are typical LMW-GS genes and closely related to the genes on chromosome 1D. Besides, secondary structure prediction of proteins indicated that, in the three LMW-GSs, random loop accounts for no less than 70 %, α-helix amounts to 26 %, average, and only 1.4 %~1.7 % is β-sheet.

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