Influence of the secondary structure on the AIE-related emission behavior of an amphiphilic polypeptide containing a hydrophobic fluorescent terminal and hydrophilic pendant groups

2016 ◽  
Vol 7 (1) ◽  
pp. 153-163 ◽  
Author(s):  
Li-Yang Lin ◽  
Po-Chiao Huang ◽  
Deng-Jie Yang ◽  
Jhen-Yan Gao ◽  
Jin-Long Hong
Keyword(s):  
Secondary Structure ◽  
Secondary Structures ◽  
Random Coil ◽  
Emission Behavior ◽  
Α Helix ◽  
Β Sheet

AIE-related emission of polypeptide containing an AIE-active terminal is correlated with secondary structures (α-helix, β-sheet and random coil) of the peptide chains.

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

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.

Effect of High Pressure Microfluidization on Secondary Structure of Wheat Gluten in Different Solvents

2013 ◽  
Vol 781-784 ◽  
pp. 770-773
Author(s):  
Zhao Xi Fang ◽  
Nai Jun Yan ◽  
Guo Qin Liu
Keyword(s):  
High Pressure ◽  
Secondary Structure ◽  
Acid Treatment ◽  
Wheat Gluten ◽  
Control Sample ◽  
Random Coil ◽  
Comprehensive Treatment ◽  
Gluten Protein ◽  
Α Helix ◽  
Β Sheet

Far-UV circular dichroism (CD) spectroscopy was used to study the conformation of wheat gluten protein treatmented by dynamic high pressure microfluidization (DHPM), acid treatment and its comprehensive treatment in two solvents. The results showed, the secondary structure of control sample are mainly consist of α-helix and random-coil in phosphate-buffered saline (PBS) and phosphate buffered solution with SDS(SDS), the secondary structure of control sample are mainly consist of β-Sheet and random-coil. The CD data also showed that SDS interacts with the gluten protein and modifies the protein conformation, which switched the conformation from α-helix and β-Turn to β-sheet and random-coil. However, the CD analysis also indicated that some of the ordered structures of α-helix, β-Turn and β-sheet were destroyed and converted random-coil coped with acid in two solvents, in other words, the acid treatment can directed change the secondary structure. Furthermore, the effect of comprehensive treatment (DHPM plus acid) is not equal to the simple sum of the individual treatment effect.

scholarly journals Secondary structure of NADPH: protochlorophyllide oxidoreductase examined by circular dichroism and prediction methods*

1996 ◽  
Vol 317 (2) ◽  
pp. 549-555 ◽  
Author(s):  
Simon J. BIRVE ◽  
Eva SELSTAM ◽  
Lennart B.-Å. JOHANSSON
Keyword(s):  
Secondary Structure ◽  
Fluorescence Emission ◽  
Random Coil ◽  
Prolamellar Body ◽  
Interfacial Region ◽  
Protochlorophyllide Oxidoreductase ◽  
Loop Region ◽  
Rossmann Fold ◽  
Α Helix ◽  
Β Sheet

To study the secondary structure of the enzyme NADPH: protochlorophyllide oxidoreductase (PCOR), a novel method of enzyme isolation was developed. The detergent isotridecyl poly(ethylene glycol) ether (Genapol X-080) selectively solubilizes the enzyme from a prolamellar-body fraction isolated from wheat (Triticum aestivumL.). The solubilized fraction was further purified by ion-exchange chromatography. The isolated enzyme was studied by fluorescence spectroscopy at 77 K, and by CD spectroscopy. The fluorescence-emission spectra revealed that the binding properties of the substrate and co-substrate were preserved and that photo-reduction occurred. The CD spectra of PCOR were analysed for the relative amounts of the secondary structures, α-helix, β-sheet, turn and random coil. The secondary-structure composition was estimated to be 33% α-helix, 19% β-sheet, 20% turn and 28% random coil. These values are in agreement with those predicted by the Predict Heidelberg Deutschland and self-optimized prediction method from alignments methods. The enzyme has some amino acid identity with other NADPH-binding enzymes containing the Rossmann fold. The Rossmann-fold fingerprint motif is localized in the N-terminal region and at the expected positions in the predicted secondary structure. It is suggested that PCOR is anchored to the interfacial region of the membrane by either a β-sheet or an α-helical region containing tryptophan residues. A hydrophobic loop-region could also be involved in membrane anchoring.

scholarly journals Role of Characteristics of External Mechanical Stress and Substrate on the Characteristics of Insulin Aggregates

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Mechanical Stress ◽  
Shear Force ◽  
Chemical Nature ◽  
Secondary Structures ◽  
Random Coil ◽  
Adsorbed Protein ◽  
Continuous Shear ◽  
Α Helix ◽  
Β Sheet

The role of chemical nature of the surface and mechanical stress on the properties of insulin in solution kept in the container is explored. The mechanical stress can be applied in the form of shear force or shaking of content in vials. The process of shear can be continuous or intermittent periodic stoppage of shear. We have observed the secondary structures of insulin present over the surface and in the solution. In addition, we have observed the distribution of insulin size, which arises due to their aggregation in solution. The properties are found to depend on the processes of applying mechanical force on a solution. The conversions of α-helix to β-sheet for continuous shear, but to intermolecular β-sheet in presence of the interrupted shear are found. The later phenomenon leads to the formation of a bigger particle. The shaking of the content of vials leads to the formation of particles with the higher random coil. The combined effect of shaking and chemical nature of surface on the aggregates’ properties is also observed. The size distribution and secondary structures of aggregates of insulin in solution are strongly dependent on the chemical nature of the surface. These are explained through desorption of the adsorbed protein. The higher rate desorption of protein from lesser hydrophobic surfaces leads to the formation of bigger insulin aggregates.

Multicomponent Peak Modeling of Protein Secondary Structures: Comparison of Gaussian with Lorentzian Analytical Methods for Plant Feed and Seed Molecular Biology and Chemistry Research

2005 ◽  
Vol 59 (11) ◽  
pp. 1372-1380 ◽  
Author(s):  
Peiqiang Yu
Keyword(s):  
Secondary Structure ◽  
Nutritive Value ◽  
Secondary Structures ◽  
Plant Seed ◽  
Relative Percentage ◽  
Protein Secondary Structures ◽  
Ft Ir ◽  
Ir Microspectroscopy ◽  
Α Helix ◽  
Β Sheet

The objective of this study was to compare Gaussian and Lorentzian multicomponent peak modeling methods in quantification of protein secondary structures of various plant seed and feed tissues within intact tissue at a cellular and subcellular level using the advanced synchrotron light sourced Fourier transform infrared (FT-IR) microspectroscopy (S-FTIR). This experiment was performed at the beamline U10B at the National Synchrotron Light Source (NSLS) in Brookhaven National Laboratory (BNL), U.S. Dept of Energy (NSLS-BNL, NY). The results show that in the comparison of the Gaussian and Lorentzian multi-peak modeling methods, the Gaussian method is more accurate for fitting multi-peak curves of protein secondary structures than the Lorentzian method, with higher modeling R2 values (0.92 versus 0.89, P < 0.05). There were no large differences ( P > 0.05) in the quantification of the relative percentage of α-helices, β-sheets, and others in protein secondary structures of the plant seed tissues, with averages of 30.2%, 40.4%, and 29.4%, respectively. However, there are significant differences ( P < 0.05) in the quantification of the ratios of β-sheet to α-helix (1.42 versus 1.60; SEM = 0.058) in protein secondary structures of the plant seed tissues. With synchrotron FT-IR microspectroscopy, the ultrastructural–chemical makeup and nutritive characteristics could be revealed at a high spatial resolution. Synchrotron-based FT-IR microspectroscopy revealed that the secondary structure of protein differed between the plant seed tissues in terms of relative percentage and ratio of protein secondary structures (α-helix and β-sheet) within cellular dimensions. The results also show that the flaxseed tissues contained higher ( P < 0.05) percentage of α-helix (38.6 versus 24.0%) and β-sheet (45.3 versus 36.9%), lower ( P < 0.05) percentage of other secondary structures (16.1% versus 39.0%), and higher ( P < 0.05) ratios of α-helix to β-sheet (0.90 versus 0.69) than the winterfat seed tissues. It must be mentioned that the relative percentages of protein secondary structure may not reflect the true secondary structure. However, the purpose of modeling the relative percentage of secondary structure was to detect the variety of differences among seed/feed/plant tissues and their relation to nutritive value and digestive behavior. The results demonstrate the potential of highly spatially resolved synchrotron-based FT-IR microspectroscopy to reveal protein secondary structures of the plant seed/feed tissues. Further study is needed to quantify the relationship between protein secondary structures and nutrient availability and digestive behavior of various varieties of plant seed tissues. Information from the infrared probing of protein secondary structures can be valuable as a guide to maintaining protein nutritive value and quality for animal and human use.

scholarly journals Protein secondary structures (α-helix and β-sheet) at a cellular level and protein fractions in relation to rumen degradation behaviours of protein: a new approach

2005 ◽  
Vol 94 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Peiqiang Yu
Keyword(s):  
Nutritive Value ◽  
Secondary Structures ◽  
Cellular Level ◽  
Heat Processing ◽  
Molecular Chemistry ◽  
New Approach ◽  
Ftir Microspectroscopy ◽  
Protein Secondary Structures ◽  
Α Helix ◽  
Β Sheet

Studying the secondary structure of proteins leads to an understanding of the components that make up a whole protein, and such an understanding of the structure of the whole protein is often vital to understanding its digestive behaviour and nutritive value in animals. The main protein secondary structures are the α-helix and β-sheet. The percentage of these two structures in protein secondary structures influences protein nutritive value, quality and digestive behaviour. A high percentage of β-sheet structure may partly cause a low access to gastrointestinal digestive enzymes, which results in a low protein value. The objectives of the present study were to use advanced synchrotron-based Fourier transform IR (S-FTIR) microspectroscopy as a new approach to reveal the molecular chemistry of the protein secondary structures of feed tissues affected by heat-processing within intact tissue at a cellular level, and to quantify protein secondary structures using multicomponent peak modelling Gaussian and Lorentzian methods, in relation to protein digestive behaviours and nutritive value in the rumen, which was determined using the Cornell Net Carbohydrate Protein System. The synchrotron-based molecular chemistry research experiment was performed at the National Synchrotron Light Source at Brookhaven National Laboratory, US Department of Energy. The results showed that, with S-FTIR microspectroscopy, the molecular chemistry, ultrastructural chemical make-up and nutritive characteristics could be revealed at a high ultraspatial resolution (∼10 μm). S-FTIR microspectroscopy revealed that the secondary structure of protein differed between raw and roasted golden flaxseeds in terms of the percentages and ratio of α-helixes and β-sheets in the mid-IR range at the cellular level. By using multicomponent peak modelling, the results show that the roasting reduced (P<0·05) the percentage of α-helixes (from 47·1 % to 36·1 %: S-FTIR absorption intensity), increased the percentage of β-sheets (from 37·2 % to 49·8 %: S-FTIR absorption intensity) and reduced the α-helix to β-sheet ratio (from 0·3 to 0·7) in the golden flaxseeds, which indicated a negative effect of the roasting on protein values, utilisation and bioavailability. These results were proved by the Cornell Net Carbohydrate Protein System in situ animal trial, which also revealed that roasting increased the amount of protein bound to lignin, and well as of the Maillard reaction protein (both of which are poorly used by ruminants), and increased the level of indigestible and undegradable protein in ruminants. The present results demonstrate the potential of highly spatially resolved synchrotron-based infrared microspectroscopy to locate ‘pure’ protein in feed tissues, and reveal protein secondary structures and digestive behaviour, making a significant step forward in and an important contribution to protein nutritional research. Further study is needed to determine the sensitivities of protein secondary structures to various heat-processing conditions, and to quantify the relationship between protein secondary structures and the nutrient availability and digestive behaviour of various protein sources. Information from the present study arising from the synchrotron-based IR probing of the protein secondary structures of protein sources at the cellular level will be valuable as a guide to maintaining protein quality and predicting digestive behaviours.

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 (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.

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