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.

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.

Preparation and Characterization of Wool Keratin/PVA Blended Films

2011 ◽  
Vol 175-176 ◽  
pp. 132-136 ◽  
Author(s):  
Ming Xia Gou ◽  
Xu Hong Yang
Keyword(s):  
Aqueous Solution ◽  
Random Coil ◽  
Ftir Analysis ◽  
Microscopy Investigation ◽  
Electron Microscopy Investigation ◽  
Scanning Electron Microscopy Investigation ◽  
Α Helix ◽  
Β Sheet ◽  
Wool Keratin

The method of extracting protein from wool was studied for the purpose of reusing the waste wool. The aqueous solution of wool keratin was prepared with Sodium Shlfide as reductive agent. In this paper, PVA was used to mix with keratin in different proportions. Both solutions were cast to obtain blended films. Scanning electron microscopy investigation showed that the surface of blended films was rough and uneven and the surface of the pure keratin film had small peridiole. FTIR analysis indicated that the secondary structure of the keratin was influenced by the blending ratios. Compared with wool fiber, the keratin film cast from aqueous solution showed a decrease in the amount of α-helix structure, while β-sheet and random coil conformations increased. When the keratin solution and PVA solution were blended in the ratios of 40:60, the film was flexible and rigid, and had good mechanical properties. This study encourages the further investigation of the applications of wool keratin films in the biomedical field, which could provide a new way to reuse various waste feathers.

Characterization of Putative a (1,3)-β-D-glucan (curdlan) Synthase for a Low Molecular Weight Curdlan Biosynthesis from Agrobacterium sp. M503

2013 ◽  
Vol 807-809 ◽  
pp. 2031-2034
Author(s):  
Yu Mei Li ◽  
Qiang Li ◽  
Sheng Han ◽  
Dong Xue Song ◽  
Yan Hong Qu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Random Coil ◽  
Low Molecular Weight ◽  
Base Pairs ◽  
Reading Frame ◽  
Coil Structure ◽  
Α Helix ◽  
Encoding Protein ◽  
Β Sheet

A β-(1,3)-D-glucan (curdlan) synthase gene for a low molecular weight curdlan biosynthesis, crdSAg, from Agrobacterium sp. M503 was cloned and its encoding protein was characterized by several online protein analysis softwares. The crdSAg consists of 1965-base-pairs Open Reading Frame (ORF) encoding a protein with molecular weight approximate 73.5 kDa, which contains the conserved domain of CESA-CelA_like belonging to glycosyltransferase family 2 (GT2). Moreover, CrdSAg was a membrane protein with seven hydrophobic transmembrance domains. The second structure analysis indicated it was composed of 43.12% α-helix, 17.89% β-sheet, and 38.99% random coil structure. These data will lay a foundation to clarify the biosynthesis mechanism of the low molecular weight curdlan.

Fabrication and Characterization of Core-Shell Structured Composite Nanofibrous Scaffolds by Coaxial Electrospinning

2011 ◽  
Vol 393-395 ◽  
pp. 754-757
Author(s):  
Qing Ye ◽  
Kui Hua Zhang ◽  
Sheng Bao Ke ◽  
Chao Liang Wang ◽  
Hong Yi Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Test ◽  
Ethanol Vapor ◽  
Random Coil ◽  
Coaxial Electrospinning ◽  
Core Shell ◽  
Nanofibrous Scaffolds ◽  
Transmission Electron ◽  
Β Sheet

Biodegradable core-shell structured nanofibrous scaffolds with silk fibroin (SF) and poly(L-lactic acid-co-ε-caprolactone) (P(LLA-CL)) blends as shell and bovine serum albumin (BSA)-containing SF as core were fabricated by coaxial electrospinning. Morphology and microstructure of the nanofibers were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results demonstrated that core-shell structured nanofibers were obtained, furthermore, the nanofibers became greatly uniform and the average diameters were thinner in comparison with only core BSA solution after adding 10-20 w/v% SF in core BSA solution. The 13C NMR clarified the SF conformation transformed from random coil to β-sheet when treated with 75 w/v % ethanol vapor. The mechanical test showed core-shell structured nanofibrous scaffolds possessed good mechanical properties but lower than SF/P(LLA-CL) blended nanofibrous scaffolds.

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.

CONFORMATION AND PHASE TRANSITION OF POLY-GLUTAMINE

2006 ◽  
Vol 17 (02) ◽  
pp. 235-246 ◽  
Author(s):  
GÖKHAN GÖKOĞLU ◽  
TARIK ÇELİK
Keyword(s):  
Low Temperatures ◽  
Low Energy ◽  
Random Coil ◽  
Polyglutamine Diseases ◽  
Aggregate Formation ◽  
Two Phase ◽  
Coil Transition ◽  
Energy Stable ◽  
Α Helix ◽  
Β Sheet

In order to provide insights into the misfolding mechanism and the subsequent aggregate formation which cause what are known as the neurodegenerative polyglutamine diseases, we have simulated a 10-residue polyglutamine (poly-Q) chain in vacuum and in solvent by multicanonical method, which enabled us to study the system in a wide temperature range and discuss thermodynamic properties. It is understood that the system in vacuum shows two phase transitions, first of them occur at high temperature that is the well-known helix-coil transition and the second one is a solid-solid transition. However, the poly-Q chain in solvent is in a random coil state at higher temperatures, goes through a conformational change at T = 200 K and assumes predominantly a mixture of anti-parallel β-sheet and α-helix structures at low temperatures. One-residue glutamine dipeptide is also simulated and low-energy stable conformations are identified.

Breakdown and reassociation of bacterial spinae

1982 ◽  
Vol 28 (7) ◽  
pp. 795-808
Author(s):  
K. B. Easterbrook ◽  
R. W. Coombs
Keyword(s):  
Ionic Strength ◽  
Protein Conformation ◽  
High Ionic Strength ◽  
Random Coil ◽  
Temperature Dependent ◽  
Calcium Effect ◽  
Α Helix ◽  
Low Ionic Strength ◽  
Β Sheet ◽  
Polymeric Structures

The tubular appendage, spina (Easterbrook and Coombs. 1976. Can. J. Microbiol. 22: 438–440), dissociates most efficiently under conditions of low ionic strength (0.01 M), high pH (10), and high temperature (95 °C). The protomer, spinin, thus produced is stable under these conditions and reassociates on cooling to give two distinct filamentous polymeric structures that differ in their stability, protein conformation, and reassociation characteristics. Under conditions of low ionic strength (0.01 M), reassociation is relatively slow and leads to a product that has significant amounts of α-helix in addition to the high β-sheet component; under conditions of high ionic strength (1 M), reassociation is rapid and the non-β-sheet component is in the random coil configuration. Since polymerization of the latter structure is "seeded" by either endogenous or exogenously supplied spina fragments, the protomers comprising it are assumed to be in the same conformation as in the spinae. High ionic strength induces folding of the protomer, multimeric association, and finally, elongation by a temperature-dependent process. Reassociation appears to be pH (6–10) independent and, apart from a possible minor calcium effect, cation nonspecific.

scholarly journals Raman Evidence of p53-DBD Disorder Decrease upon Interaction with the Anticancer Protein Azurin

2019 ◽  
Vol 20 (12) ◽  
pp. 3078 ◽  
Author(s):  
Sara Signorelli ◽  
Salvatore Cannistraro ◽  
Anna Rita Bizzarri
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Principal Component ◽  
Intrinsically Disordered Protein ◽  
Random Coil ◽  
Disordered Proteins ◽  
Conformational Heterogeneity ◽  
Intrinsically Disordered ◽  
Tryptophan Residues ◽  
Α Helix ◽  
Β Sheet

Raman spectroscopy, which is a suitable tool to elucidate the structural properties of intrinsically disordered proteins, was applied to investigate the changes in both the structure and the conformational heterogeneity of the DNA-binding domain (DBD) belonging to the intrinsically disordered protein p53 upon its binding to Azurin, an electron-transfer anticancer protein from Pseudomonas aeruginosa. The Raman spectra of the DBD and Azurin, isolated in solution or forming a complex, were analyzed by a combined analysis based on peak inspection, band convolution, and principal component analysis (PCA). In particular, our attention was focused on the Raman peaks of Tyrosine and Tryptophan residues, which are diagnostic markers of protein side chain environment, and on the Amide I band, of which the deconvolution allows us to extract information about α-helix, β-sheet, and random coil contents. The results show an increase of the secondary structure content of DBD concomitantly with a decrease of its conformational heterogeneity upon its binding to Azurin. These findings suggest an Azurin-induced conformational change of DBD structure with possible implications for p53 functionality.

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 Solvent on the Characteristics of Electrospun Regenerated Silk Fibroin Nanofibers

2007 ◽  
Vol 342-343 ◽  
pp. 813-816 ◽  
Author(s):  
Lim Jeong ◽  
Kuen Yong Lee ◽  
Won Ho Park
Keyword(s):  
Secondary Structure ◽  
Formic Acid ◽  
Silk Fibroin ◽  
Structural Changes ◽  
Effective Means ◽  
Electrospun Nanofibers ◽  
Random Coil ◽  
Regenerated Silk Fibroin ◽  
Silk Fibroin Nanofibers ◽  
Β Sheet

Nonwoven nanofiber matrices were prepared by electrospinning a solution of silk fibroin (SF) dissolved either in formic acid or in 1,1,1,3,3,3-hexafluoro-2-isopropyl alcohol (HFIP). The mean diameter of the electrospun nanofibers prepared from SF dissolved in formic acid was 80 nm with a unimodal size distribution, which was smaller than those prepared from HFIP (380 nm). SF nanofibers were then treated with an aqueous methanol solution, and structural changes due to solvent-induced crystallization of SF were investigated using IR and 13C solid-state CP/MAS NMR spectroscopy. SF nanofibers prepared from formic acid were found to have a higher proportion of β-sheet conformations than those prepared from HFIP. Methanol treatment provided a fast and effective means to alter the secondary structure of both types of SF nanofibers from a random coil form to a β-sheet form. As demonstrated in the present study, this approach to controlling the dimensions and secondary structure of proteins using various solvents may be useful for the design and tailoring of materials for biomedical applications, especially for tissue engineering applications.

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