Charge-Induced Secondary Structure Transformation of Amyloid-Derived Dipeptide Assemblies from β-Sheet to α-Helix

2018 ◽  
Vol 57 (6) ◽  
pp. 1537-1542 ◽  
Author(s):  
Ruirui Xing ◽  
Chengqian Yuan ◽  
Shukun Li ◽  
Jingwen Song ◽  
Junbai Li ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Structure Transformation ◽  
Α Helix ◽  
Β Sheet

Charge-Induced Secondary Structure Transformation of Amyloid-Derived Dipeptide Assemblies from β-Sheet to α-Helix

2018 ◽  
Vol 130 (6) ◽  
pp. 1553-1558 ◽  
Author(s):  
Ruirui Xing ◽  
Chengqian Yuan ◽  
Shukun Li ◽  
Jingwen Song ◽  
Junbai Li ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Structure Transformation ◽  
Α Helix ◽  
Β Sheet

Use of synchrotron-based FTIR microspectroscopy to determine protein secondary structures of raw and heat-treated brown and golden flaxseeds: A novel approach

2005 ◽  
Vol 85 (4) ◽  
pp. 437-448 ◽  
Author(s):  
P. Yu ◽  
J. J. McKinnon ◽  
H. W. Soita ◽  
C. R. Christensen ◽  
D. A. Christensen
Keyword(s):  
Secondary Structure ◽  
Matrix Protein ◽  
Protein Secondary Structure ◽  
Secondary Structures ◽  
Heat Processing ◽  
Lower Percentage ◽  
Protein Secondary Structures ◽  
Novel Approach ◽  
Α Helix ◽  
Β Sheet

The objectives of the study were to use synchrotron Fourier transform infrared microspectroscopy (S-FTIR) as a novel approach to: (1) reveal ultra-structural chemical features of protein secondary structures of flaxseed tissues affected by variety (golden and brown) and heat processing (raw and roasted), and (2) quantify protein secondary structures using Gaussian and Lorentzian methods of multi-component peak modeling. By using multi-component peak modeling at protein amide I region of 1700–1620 cm-1, the results showed that the golden flaxseed contained relatively higher percentage of α-helix (47.1 vs. 36.9%), lower percentage of β-sheet (37.2 vs. 46.3%) and higher (P < 0.05) ratio of α-helix to β-sheet than the brown flaxseed (1.3 vs. 0.8). The roasting reduced (P < 0.05) percentage of α-helix (from 47.1 to 36.1%), increased percentage of β-sheet (from 37.2 to 49.8%) and reduced α-helix to β-sheet ratio (1.3 to 0.7) of the golden flaxseed tissues. However, the roasting did not affect percentage and ratio of α-helix and β-sheet in the brown flaxseed tissue. No significant differences were found in quantification of protein secondary structures between Gaussian and Lorentzian methods. These results demonstrate the potential of highly spatially resolved S-FTIR to localize relatively pure protein in the tissue and reveal protein secondary structures at a cellular level. The results indicated relative differences in protein secondary structures between flaxseed varieties and differences in sensitivities of protein secondary structure to the heat processing. Further study is needed to understand the relationship between protein secondary structure and protein digestion and utilization of flaxseed and to investigate whether the changes in the relative amounts of protein secondary structures are primarily responsible for differences in protein availability. Key words: Synchrotron, FTIR microspectrosopy, flaxseeds, intrinsic structural matrix, protein secondary structures, protein nutritive value

scholarly journals (De)stabilization of Alpha-Synuclein Fibrillary Aggregation by Charged and Uncharged Surfactants

2021 ◽  
Vol 22 (22) ◽  
pp. 12509
Author(s):  
Joana Angélica Loureiro ◽  
Stéphanie Andrade ◽  
Lies Goderis ◽  
Ruben Gomez-Gutierrez ◽  
Claudio Soto ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Hydrophobic Interactions ◽  
Neurodegenerative Disorder ◽  
Sodium Dodecyl ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Cetyltrimethylammonium Chloride ◽  
Α Helix ◽  
Β Sheet

Parkinson’s disease (PD) is the second most common neurodegenerative disorder. An important hallmark of PD involves the pathological aggregation of proteins in structures known as Lewy bodies. The major component of these proteinaceous inclusions is alpha (α)-synuclein. In different conditions, α-synuclein can assume conformations rich in either α-helix or β-sheets. The mechanisms of α-synuclein misfolding, aggregation, and fibrillation remain unknown, but it is thought that β-sheet conformation of α-synuclein is responsible for its associated toxic mechanisms. To gain fundamental insights into the process of α-synuclein misfolding and aggregation, the secondary structure of this protein in the presence of charged and non-charged surfactant solutions was characterized. The selected surfactants were (anionic) sodium dodecyl sulphate (SDS), (cationic) cetyltrimethylammonium chloride (CTAC), and (uncharged) octyl β-D-glucopyranoside (OG). The effect of surfactants in α-synuclein misfolding was assessed by ultra-structural analyses, in vitro aggregation assays, and secondary structure analyses. The α-synuclein aggregation in the presence of negatively charged SDS suggests that SDS-monomer complexes stimulate the aggregation process. A reduction in the electrostatic repulsion between N- and C-terminal and in the hydrophobic interactions between the NAC (non-amyloid beta component) region and the C-terminal seems to be important to undergo aggregation. Fourier transform infrared spectroscopy (FTIR) measurements show that β-sheet structures comprise the assembly of the fibrils.

scholarly journals Prion Interaction with Normal Protein in Topological Changing Secondary Structure to Aggregation

2020 ◽  
Vol 9 (2) ◽  
pp. 53
Author(s):  
Yao Yao
Keyword(s):  
Hydrogen Bond ◽  
Secondary Structure ◽  
Amyloid Fibril ◽  
Double Helix ◽  
Β Amyloid ◽  
Structural Analogy ◽  
Β Sheets ◽  
Α Helix ◽  
Dna Double Helix ◽  
Β Sheet

<p>Prion is a protein smaller than virus and it infects host in the absence of nucleic acid. The secondary structure of protein folds incorrectly from α-helices to β-sheets through breaking and re-formation of hydrogen bond. Structural analogy of α-helix and DNA double helix and comparing differences between α-helix and β-sheet show prion's infectivity and propagation. Aggregates of dimers and polymers generate β-amyloid fibril in Alzheimer's disease.</p>

Phospholipid-Specific Conformational Changes in Human Prothrombin upon Binding to Procoagulant Acidic Lipid Membranes

1994 ◽  
Vol 71 (05) ◽  
pp. 596-604 ◽  
Author(s):  
Jogin R Wu ◽  
Barry R Lentz
Keyword(s):  
Secondary Structure ◽  
Conformational Changes ◽  
Lipid Membranes ◽  
Membrane Vesicles ◽  
Scanning Calorimetry ◽  
Domain Organization ◽  
Α Helix ◽  
Β Sheet ◽  
Prothrombin Activation

SummaryThis paper provides evidence to demonstrate that human prothrombin undergoes conformational changes upon binding to procoagulant membranes specifically containing phosphatidylserine (PS). Fourier transform infrared spectroscopy was used to show a slight increase in ordered (α-helix, β-sheet, β-turns) secondary structure upon binding to PS-containing membranes. Thermograms representing prothrombin and prothrombin fragment 1 denaturation were obtained using differential scanning calorimetry. These were analyzed and interpreted in terms of changes in prothrombin domain organization associated with binding to PS-containing membranes. Changes in either secondary structure or domain organization upon binding to negatively-charged phosphatidylglycerol-containing membranes were, if they occurred at all, much less dramatic. The results paralleled results obtained previously with bovine prothrombin (1, 2). The implications of these results in terms of a possible molecular mechanism for the cofactor-like role of platelet membrane vesicles in prothrombin activation are discussed.

What vibrations tell about proteins

2002 ◽  
Vol 35 (4) ◽  
pp. 369-430 ◽  
Author(s):  
Andreas Barth ◽  
Christian Zscherp
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Ir Spectroscopy ◽  
Reaction Mechanisms ◽  
Amino Acid Side Chain ◽  
Difference Spectroscopy ◽  
Transition Dipole ◽  
Dipole Coupling ◽  
Α Helix ◽  
Β Sheet

1. Introduction 3702. Infrared (IR) spectroscopy – general principles 3722.1 Vibrations 3722.2 Information that can be derived from the vibrational spectrum 3722.3 Absorption of IR light 3753. Protein IR absorption 3763.1 Amino-acid side-chain absorption 3763.2 Normal modes of the amide group 3814. Interactions that shape the amide I band 3824.1 Overview 3824.2 Through-bond coupling 3834.3 Hydrogen bonding 3834.4 Transition dipole coupling (TDC) 3835. The polarization and IR activity of amide I modes 3875.1 The coupled oscillator system 3875.2 Optically allowed transitions 3885.3 The infinite parallel β-sheet 3885.4 The infinite antiparallel β-sheet 3895.5 The infinite α-helix 3906. Calculation of the amide I band 3916.1 Overview 3916.2 Perturbation treatment by Miyazawa 3936.3 The parallel β-sheet 3946.4 The antiparallel β-sheet 3956.5 The α-helix 3966.6 Other secondary structures 3987. Experimental analysis of protein secondary structure 3987.1 Band fitting 3987.2 Methods using calibration sets 4017.3 Prediction quality 4038. Protein stability 4048.1 Thermal stability 4048.2 1H/2H exchange 4069. Molecular reaction mechanisms of proteins 4089.1 Reaction-induced IR difference spectroscopy 4089.2 The origin of difference bands 4099.3 The difference spectrum seen as a fingerprint of conformational change 4109.4 Molecular interpretation: strategies of band assignment 41610. Outlook 41911. Acknowledgements 42012. References 420This review deals with current concepts of vibrational spectroscopy for the investigation of protein structure and function. While the focus is on infrared (IR) spectroscopy, some of the general aspects also apply to Raman spectroscopy. Special emphasis is on the amide I vibration of the polypeptide backbone that is used for secondary-structure analysis. Theoretical as well as experimental aspects are covered including transition dipole coupling. Further topics are discussed, namely the absorption of amino-acid side-chains, 1H/2H exchange to study the conformational flexibility and reaction-induced difference spectroscopy for the investigation of reaction mechanisms with a focus on interpretation tools.

High-Pressure FTIR Studies of the Secondary Structure of Proteins

1996 ◽  
Author(s):  
Yoshihiro Taniguchi ◽  
Naohiro Takeda
Keyword(s):  
High Pressure ◽  
Secondary Structure ◽  
Cytochrome C ◽  
Ribonuclease A ◽  
Random Coil ◽  
Absorbance Spectroscopy ◽  
Α Helix ◽  
Bovine Pancreas ◽  
Β Sheet ◽  
Denaturation Of Proteins

Infrared spectra of five globular proteins (bovine pancreas ribonuclease A, horse skeletal muscle myoglobin, bovine pancreas insulin, horse heart cytochrome c, egg white lysozyme) in 5% D2O solutions (pD 7.0) were measured as a function of pressure up to 1470 MPa at 30 °C. According to the second-derivative spectral changes in the observed amide I band of the proteins, which indicate that the α-helix and β-sheet substructures of the secondary structures break dramatically into the random coil conformation, ribonuclease A and myoglobin are denatured reversibly at 850 MPa and 350 MPa, respectively. Lysozyme denatures partially and reversibly at 670 MPa, as shown by decrease in the α-helix and β-turn substructures, but no change occurs in the random coil and β-sheet substructures. The secondary structure of cytochrome c is not disrupted at pressures up to 1470 MPa, and partial transformation of the α-helix of insulin to random coil starts at 960 MPa. Hydrogen-deuterium exchange of protons on the amide groups in the protein interior is increased by external pressure and is associated with the pressure-induced protein conformational changes. A number of studies on the effects of pressure on protein denaturation have been carried out using various high-pressure detection methods: ultraviolet absorbance spectroscopy (Brandts et al., 1970; Hawley, 1971), visible absorbance spectroscopy (Zipp & Kauzmann, 1973), fluorescence intensity spectroscopy (Li et al., 1976), polarization fluorescence spectroscopy (Chryssomallis et al., 1981), and enzyme activity assays (Taniguchi & Suzuki, 1983; Makimoto et al., 1989). These techniques have the great advantage of being applicable to pressure-induced reversible denaturation of proteins to identify the thermodynamic parameters, especially the volume change and compressibility of a protein in solution, because the experiments can be run under dilute conditions at a protein concentration of less than 0.05% w/v. Therefore, these data reflect the intramolecular phenomena of reversible pressure changes and provide the volume changes accompanying the denaturation of proteins, which are due to the difference in partial molal (specific) volume between the native and denatured proteins in solution.

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