Anisotropic Optical Constants of α-Helix and β-Sheet Secondary Structures in the Infrared

2000 ◽  
Vol 104 (18) ◽  
pp. 4537-4544 ◽  
Author(s):  
T. Buffeteau ◽  
E. Le Calvez ◽  
S. Castano ◽  
B. Desbat ◽  
D. Blaudez ◽  
...  
Keyword(s):  
Optical Constants ◽  
Secondary Structures ◽  
Α Helix ◽  
Β Sheet

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.

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

Switch peptides: Medium induced α-helix to β-sheet transitions of bis-amphiphilic secondary structures and their membrane activity

Peptides ◽  
1992 ◽  
pp. 344-345 ◽  
Author(s):  
Manfred Mutter ◽  
Karl-Heinz Altmann ◽  
Uwe Buttkus ◽  
Roland Gassmann ◽  
Lothar Kürz ◽  
...  
Keyword(s):  
Secondary Structures ◽  
Membrane Activity ◽  
Α Helix ◽  
Β Sheet

Self-assembled PEG–poly(l-valine) hydrogels as promising 3D cell culture scaffolds

2017 ◽  
Vol 5 (9) ◽  
pp. 1724-1733 ◽  
Author(s):  
Huijuan Song ◽  
Guang Yang ◽  
Pingsheng Huang ◽  
Deling Kong ◽  
Weiwei Wang
Keyword(s):  
Cell Culture ◽  
3D Cell Culture ◽  
Secondary Structures ◽  
Biomaterial Scaffolds ◽  
Self Assembled ◽  
Α Helix ◽  
Β Sheet ◽  
Biomedical Fields

Self-assembled PEGylated poly(l-valine) hydrogels with combinational α-helix and β-sheet secondary structures represented new biomaterial scaffolds in biomedical fields including but not limited to 3D cell culture.

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.

Evolution of maurotoxin conformation and blocking efficacy towards Shaker B channels during the course of folding and oxidation in vitro

2002 ◽  
Vol 361 (2) ◽  
pp. 409-416 ◽  
Author(s):  
Eric DI LUCCIO ◽  
Alessandra MATAVEL ◽  
Sandrine OPI ◽  
Imed REGAYA ◽  
Guillaume SANDOZ ◽  
...  
Keyword(s):  
Time Course ◽  
Three Dimensional ◽  
Secondary Structures ◽  
Dimensional Structure ◽  
Electrophysiological Recordings ◽  
Initial Stage ◽  
On Line ◽  
Α Helix ◽  
Β Sheet

Maurotoxin (MTX) is a 34-mer scorpion toxin cross-linked by four disulphide bridges that acts on various K+ channels, including the voltage-gated Shaker B subtype. In the present study, we have investigated over 80h: (1) the time-course of folding of synthetic MTX (sMTX) by CD analysis; (2) the kinetics of disulphide bridge formation by MS; and (3) the potency of MTX in blocking Shaker B currents during the combined process of its in vitro folding and oxidation. From the CD data, we show that stable secondary structures of sMTX evolve sequentially over time, with the appearance of the α-helix within 5h, followed by the formation of the β-sheet within 22h. Using MS analysis, the sMTX intermediates were also found to appear sequentially from the least (one-disulphide-bridged sMTX) to the most oxidized species (native-like, four-disulphide-bridged sMTX). The time course of formation of secondary structures coincides mainly with the occurrence of one-disulphide-bridged sMTX for the α-helix and two- or three-disulphide-bridged sMTX for the β-sheet. On-line electrophysiological recordings, which measure sMTX blocking efficacy on K+ currents during its folding and oxidation, were performed on Shaker B channels expressed in Xenopus oocytes. Unexpectedly, the results demonstrate that sMTX is highly potent at the initial stage of oxidation, whereas its blocking activity can be transiently and dramatically reduced at later stages during the course of folding/oxidation before it reaches full bioactivity. These data suggest that formation of disulphide bridges can both physically stabilize and alter the bioactive three-dimensional structure of sMTX.

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.

scholarly journals Hydroxyapatite Formation on Self-Assembling Peptides with Differing Secondary Structures and Their Selective Adsorption for Proteins

2019 ◽  
Vol 20 (18) ◽  
pp. 4650 ◽  
Author(s):  
Suzuka Kojima ◽  
Hitomi Nakamura ◽  
Sungho Lee ◽  
Fukue Nagata ◽  
Katsuya Kato
Keyword(s):  
Cytochrome C ◽  
Selective Adsorption ◽  
Secondary Structures ◽  
Inorganic Materials ◽  
Stabilizing Agents ◽  
Self Assembling ◽  
Group Density ◽  
Α Helix ◽  
Β Sheet ◽  
Hydroxyapatite Formation

Self-assembling peptides have been employed as biotemplates for biomineralization, as the morphologies and sizes of the inorganic materials can be easily controlled. We synthesized two types of highly ordered self-assembling peptides with different secondary structures and investigated the effects of secondary structures on hydroxyapatite (HAp) biomineralization of peptide templates. All as-synthesized HAp-peptides have a selective protein adsorption capacity for basic protein (e.g., cytochrome c and lysozyme). Moreover, the selectivity was improved as peptide amounts increased. In particular, peptide–HAp templated on β-sheet peptides adsorbed more cytochrome c than peptide–HAp with α-helix structures, due to the greater than 2-times carboxyl group density at their surfaces. It can be expected that self-assembled peptide-templated HAp may be used as carriers for protein immobilization in biosensing and bioseparation applications and as enzyme-stabilizing agents.

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