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.

Effect of Concentration on Structure and Properties of Concentrated Regenerated Silk Fibroin Solution

2011 ◽  
Vol 311-313 ◽  
pp. 1653-1656 ◽  
Author(s):  
Fang Xie ◽  
Hao Liang
Keyword(s):  
Silk Fibroin ◽  
Conformational Transition ◽  
Random Coil ◽  
Scanning Calorimetry ◽  
Regenerated Silk Fibroin ◽  
Lower Temperature ◽  
Α Helix ◽  
Β Sheet ◽  
Dsc Curves ◽  
Fibroin Solution

The thermal properties and rheological behavior of concentrated regenerated silk fibroin aqueous solution from 15% to 37% was investigated by differential scanning calorimetry (DSC) and rheometer. Also the conformation of solutions was characterized by Raman spectra. It was discovered that the major endothermic peak in the DSC curves shifted toward the lower temperature region with increasing the concentration. This behavior suggests increasing the concentration can accelerate conformational transition of silk fibroin from random coil and α-helix to β-sheet structure. In addition, it was found that the viscosity of solution increased with increasing concentration in favor of spinning.

scholarly journals Effect of pH on the Conformational Transition of Silk Fibroin in Aqueous Solution Monitored by Thioflavin-T Fluorescence

2021 ◽  
Author(s):  
Ben Jia ◽  
Lan Jia ◽  
Jingxin Zhu
Keyword(s):  
Aqueous Solution ◽  
Secondary Structure ◽  
Silk Fibroin ◽  
Conformational Transition ◽  
Thioflavin T ◽  
Random Coil ◽  
Fluorescence Dye ◽  
Assembly Behavior ◽  
Β Sheet

Abstract In this work, the potential application of the fluorescence dye Thioflavin-T (ThT), which can specifically bind to amyloid, as a powerful tool for monitoring secondary structure transitions of silk fibroin (SF) induced by pH was examined. Results showed that ThT emission intensities substantially increased when pH decreased from 6.8 to 4.8. This increase may be due to conformational transitions from random coil to β-sheet. The morphology and secondary structure of SF were also investigated via TEM, AFM and circular dichroism spectroscopy. The information obtained herein can be utilized not only for the development of convenient and efficient noninvasive method for monitoring the assembly behavior of SF in aqueous solution but also for in vitro fluorescence imaging.

EFFECT OF STORAGE TIME AND CONCENTRATION ON STRUCTURE OF REGENERATED SILK FIBROIN SOLUTION

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3878-3883 ◽  
Author(s):  
FANG XIE ◽  
HUILI SHAO ◽  
XUECHAO HU
Keyword(s):  
Aqueous Solution ◽  
Silk Fibroin ◽  
Storage Time ◽  
Conformational Transition ◽  
Solution Concentration ◽  
Cd Spectroscopy ◽  
Random Coil ◽  
Conformational Transformation ◽  
Regenerated Silk Fibroin ◽  
Α Helix

Concentrated regenerated silk fibroin (RSF) aqueous solutions with concentration close to that of the native silk fibroin (15.5%, 25.5% and 31%) were prepared. The effect of storage time and concentration on the conformational transition of the concentrated RSF aqueous solution was studied by Raman spectroscopy and circular dichroism (CD) spectroscopy. At the same time, the conformational change of RSF aqueous solution in flowing state was also investigated. It was found that the conformation of silk fibroin was changed gradually from random coil/α-helix to β-sheet structure during the storage. And the conformational transformation was accelerated with the increasing of the RSF aqueous solution concentration. When the solution was in flowing state, the conformational transformation was also accelerated.

Conformational Preferences of Aβ25-35 and Aβ35-25 in Membrane Mimicking Environments

2019 ◽  
Vol 26 (5) ◽  
pp. 386-390
Author(s):  
Dhandayuthapani Sambasivam ◽  
Senthilkumar Sivanesan ◽  
Sayeeda Sultana ◽  
Jayakumar Rajadas
Keyword(s):  
Structural Transition ◽  
Conformational Transition ◽  
The Other ◽  
Random Coil ◽  
Structural Modifications ◽  
Sds Micelles ◽  
Conformational Preferences ◽  
Helix Conformation ◽  
Α Helix ◽  
Β Sheet

Background: The structural transition of aggregating Abeta peptides is the key event in the progression of Alzheimer’s Disease (AD). Objective: In the present work, the structural modifications of toxic Aβ25-35 and the scrambled Aβ35-25 were studied in Trifluoroethanol (TFE) and in aqueous SDS micelles. Methods: Using CD spectroscopic investigations, the conformational transition of Aβ25-35 and Aβ35-25 peptides were determined in different membrane mimicking environments such as TFE and SDS. An interval scan CD of the peptides on evaporation of TFE was performed. TFE titrations were carried out to investigate the intrinsic ability of the structural conformations of peptides. Results: We show by spectroscopic evidence that Aβ25-35 prefers beta sheet structures upon increasing TFE concentrations. On the other hand, the non-toxic scrambled Aβ35-25 peptide only undergoes a transition from random coil to α-helix conformation with increasing TFE. In the interval scan studies, Aβ25-35 did not show any structural transitions, whereas Aβ35-25 showed transition from α-helix to β-sheet conformation. In membrane simulating aqueous SDS micelles, Aβ25-35 showed a transition from random coil to α-helix while Aβ35-25 underwent transition from random coil to β-sheet conformation. Conclusion: Overall, the current results seek new insights into the structural properties of amyloidogenic and the truncated sequence in membrane mimicking solvents.

Preparation of Water-Insoluble Antheraea Pernyi Silk Fibroin Films

2012 ◽  
Vol 569 ◽  
pp. 311-315 ◽  
Author(s):  
Shen Zhou Lu ◽  
Li Mao ◽  
Yu Liu ◽  
Shan Sun ◽  
Gui Jun Li
Keyword(s):  
Silk Fibroin ◽  
Diffraction Method ◽  
Random Coil ◽  
X Ray Diffraction ◽  
Antheraea Pernyi ◽  
Blend Film ◽  
Blend Films ◽  
Thiocyanate Solution ◽  
Α Helix ◽  
Β Sheet

Antheraea pernyi silk fibroin (ASF) solution was prepared by dissolving Antheraea pernyi silk fiber in lithium thiocyanate solution. The ASF/glycol blend films were prepared by casting aqueous solution of ASF mixed with glycol. The structure of blend film was investigated by the X-ray diffraction method and infrared spectroscopy. The result showed that the structure of regenerated ASF film was α-helix and random coil conformation. After mixing with glycol, it resulted in significant increase in β-sheet structure with the improvement of water resistance of the films. This effect was strongly dependent on glycol content in the blend film. When the glycol content was more than 45 wt%, the structure of ASF changed to β-sheet and the film became water-insoluble. The breaking strength and elongation of ASF/glycol blend film were 30 Mpa and 50 %, respectively. In summary, the ASF/glycol blend film provided a great potential as a biological material.

Impact of Sterilization Methods on the Stability of Silk Fibroin Solution

2011 ◽  
Vol 311-313 ◽  
pp. 1755-1759 ◽  
Author(s):  
Xi Long Wu ◽  
Li Mao ◽  
Da Ke Qin ◽  
Shen Zhou Lu
Keyword(s):  
Aqueous Solutions ◽  
Gamma Irradiation ◽  
Silk Fibroin ◽  
Conformational Changes ◽  
Conformational Transition ◽  
Treatment Time ◽  
Gelation Time ◽  
Random Coil ◽  
Γ Irradiation ◽  
Β Sheet

Different sterilization techniques such as Co(60) gamma irradiation and autoclaving were used to treat the regenerated Bombyx mori silk fibroin (RSF) in aqueous solutions. The effect of the two above mentioned sterilization methods on the conformational changes and gelation rate of RSF was studied. According to the analysis of circular dichroism spectroscopy, gamma irradiation may initiate the conformational transition from random coil to β-sheet for RSF, while autoclaving shows less significant influence on the structure changes of RSF in aqueous solutions. The results also indicate that gelation time decreased to 5 days after γ-irradiation treatment while gelation time increased to 31 days after autoclave treatment. Moreover, particles of RSF in solutions changed larger and gelation time increased when autoclaving treatment time extended. However, no detectable changes of RSF secondary structure were found investigated by XRD and FTIR. Which indicated that under both sterilization methods, the RSF structure was transformed from random coil to β-sheet structure after gelation.

Study on Silk Fibroin Gelation: Effect of Polyalcohol

2011 ◽  
Vol 175-176 ◽  
pp. 137-142 ◽  
Author(s):  
Qiang Zhang ◽  
Ying Dong Cheng ◽  
Yu Liu ◽  
Shu Qin Yan ◽  
Ming Zhong Li
Keyword(s):  
Silk Fibroin ◽  
Three Dimensional ◽  
Random Coil ◽  
X Ray Diffraction ◽  
Polyethylene Glycol 400 ◽  
Bombyx Mori Silk ◽  
Α Helix ◽  
Β Sheet ◽  
Important Form ◽  
Fibroin Solution

The Bombyx mori silk fibroin gel with three dimensional structures is an important form to be developed for tissue engineering materials. In this paper, silk fibroin gels were prepared with adding polyalcohol into silk fibroin solution. The gel structure was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The results demonstrated that when adding more than 100% of polyalcohol, both of glycerol and polyethylene glycol 400 (PEG400) can accelerate the gelation process markedly. With the increase of the percentage of PEG400 and glycerol, it promoted silk fibroin molecules to cluster rapidly and inhibit silk fibroin molecules transforming from the random coil or α-helix to β-sheet in a ratio of 900% especially. Silk fibroin gels containing 100% of polyalcohol had more uniform morphology and the pores distributed uniformly.

scholarly journals Structural and Technological Approach to Reveal the Role of the Lipid Phase in the Formation of Soy Emulsion Gels with Chia Oil

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 48
Author(s):  
Ana M. Herrero ◽  
Claudia Ruiz-Capillas
Keyword(s):  
Raman Spectroscopy ◽  
Structural Properties ◽  
Structural Changes ◽  
Protein Secondary Structure ◽  
Lipid Phase ◽  
Α Helix ◽  
Β Sheet ◽  
Shed Light ◽  
Chia Oil

Considerable attention has been paid to emulsion gels (EGs) in recent years due to their interesting applications in food. The aim of this work is to shed light on the role played by chia oil in the technological and structural properties of EGs made from soy protein isolates (SPI) and alginate. Two systems were studied: oil-free SPI gels (SPI/G) and the corresponding SPI EGs (SPI/EG) that contain chia oil. The proximate composition, technological properties (syneresis, pH, color and texture) and structural properties using Raman spectroscopy were determined for SPI/G and SPI/EG. No noticeable (p > 0.05) syneresis was observed in either sample. The pH values were similar (p > 0.05) for SPI/G and SPI/EG, but their texture and color differed significantly depending on the presence of chia oil. SPI/EG featured significantly lower redness and more lightness and yellowness and exhibited greater puncture and gel strengths than SPI/G. Raman spectroscopy revealed significant changes in the protein secondary structure, i.e., higher (p < 0.05) α-helix and lower (p < 0.05) β-sheet, turn and unordered structures, after the incorporation of chia oil to form the corresponding SPI/EG. Apparently, there is a correlation between these structural changes and the textural modifications observed.

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.

Fabrication and Characterization of Vitamin E TPGS Loaded Silk Fibroin/Hyaluronic Acid Nanofibrous Scaffolds

2013 ◽  
Vol 721 ◽  
pp. 274-277
Author(s):  
Li Li Ji ◽  
Qiao Ling Li ◽  
Zeng Hu Yang ◽  
Wei Jing Hu ◽  
Kui Hua Zhang
Keyword(s):  
Hyaluronic Acid ◽  
Vitamin E ◽  
Silk Fibroin ◽  
Ethanol Vapor ◽  
Random Coil ◽  
Burst Release ◽  
Nanofibrous Scaffolds ◽  
Vitamin E Tpgs ◽  
Polyethylene Glycol 1000 ◽  
Β Sheet

Vitamin E d-alpha-tocopheryl polyethylene glycol 1000 succinate (VE TPGS) loaded silk fibroin (SF)/ hyaluronic acid (HA) nanofibrous scaffolds were fabricated by means of electrospinning to biomimic the natural extracellular matrix. Scanning electronic microscopy (SEM) results indicated that electrospun VE TPGS loaded SF/HA nanofibers were ribbon-shaped, the width of nanofibers decreased slightly with the addition of VE TPGS to SF/HA blended solutions. Fourier transform infrared (FTIR) spectroscopy and Wide-angle X-ray diffraction (WAXD) curves revealed that VE TPGS did not induce SF conformation from random coil to β-sheet. SF conformation converted from random coil to β-sheet after being treated with 75% ethanol vapor. In vitro release studies confirmed VE TPGS had no obvious burst release and present good release behavior.

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