Conformational Changes of Facially Amphiphilicmeta-Poly(phenylene ethynylene)s in Aqueous Solution

2004 ◽  
Vol 37 (4) ◽  
pp. 1283-1288 ◽  
Author(s):  
Lachelle Arnt ◽  
Gregory N. Tew
Keyword(s):  
Aqueous Solution ◽  
Conformational Changes ◽  
Phenylene Ethynylene

scholarly journals Conformational Changes in Wheat Gluten After using Ag-nanoparticles

2014 ◽  
Vol 28 (3) ◽  
pp. 311-317 ◽  
Author(s):  
Agnieszka Nawrocka
Keyword(s):  
Aqueous Solution ◽  
Silver Nanoparticles ◽  
Secondary Structure ◽  
Conformational Changes ◽  
Fungal Infections ◽  
Wheat Gluten ◽  
Control Sample ◽  
Antimicrobial Properties ◽  
Protective Layer ◽  
Trisodium Citrate

Abstract Silver nanoparticles have antimicrobial properties since they can be regarded as an efficient protector against pathogenic microorganisms. Fourier transform infrared spectroscopy was used to examine conformational changes in the secondary structure of wheat gluten washed out from grain treated with an aqueous solution of silver nanoparticles stabilized by tri-sodium citrate. Silver nanoparticles were used as a protective layer on the grain surface against bacterial and fungal infections (antimicrobial agent). Analysis of the amide I band revealed significant changes in the secondary structure after using silver nanoparticles. An increase in the β-sheet content (from 36.2 to 39.2%) was observed at the expense of the α-helix and β-turn content. To find factors causing these changes, the wheat grains were treated by an aqueous solution of trisodium citrate and water. The results obtained indicate that the changes in the gluten structure were connected mainly with the trisodium citrate action due to presence of a small number of free molecules of the stabilizer in the solution of silver nanoparticles. Additionally, the conformational changes in gluten pointed out that gluten flexibility increased (decrease in the αH/βS ratio from 1.40 for the control sample to 1.26 for the silver nanoparticle-treated samples) as well as the solubility of gluten decreased (decrease in the β-turn content from 13.1 to 11.4%).

Conformational changes of proteins in aqueous solution induced by temperature in the pre-melting region

2001 ◽  
Vol 3 (17) ◽  
pp. 3811-3813 ◽  
Author(s):  
A. Bonincontro ◽  
E. Bultrini ◽  
V. Calandrini ◽  
G. Onori
Keyword(s):  
Aqueous Solution ◽  
Conformational Changes ◽  
Melting Region

scholarly journals Thermally induced conformational changes and protein–protein interactions of bovine serum albumin in aqueous solution under different pH and ionic strengths as revealed by SAXS measurements

2017 ◽  
Vol 19 (26) ◽  
pp. 17143-17155 ◽  
Author(s):  
Dmitry Molodenskiy ◽  
Evgeny Shirshin ◽  
Tatiana Tikhonova ◽  
Andrey Gruzinov ◽  
Georgy Peters ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Conformational Changes ◽  
Interaction Potential ◽  
Protein Interactions ◽  
Bovine Serum ◽  
Protein Protein Interactions ◽  
Thermally Induced ◽  
Before And After

Temperature-induced oligomerization of albumin before and after protein melting was studied using SAXS and interpreted in terms of interaction potential.

Measurements of Nonlinear Electrical Impedances by Virtue of Induced Conformational Changes in DNAs

2010 ◽  
Vol 22 (5) ◽  
pp. 601-607 ◽  
Author(s):  
Takatoki Yamamoto ◽  
◽  
Sangwook Lee ◽  
Teruo Fujii ◽  
Keyword(s):  
Aqueous Solution ◽  
Conformational Changes ◽  
Electrical Impedance ◽  
Dna Analysis ◽  
Electrical Impedance Spectroscopy ◽  
Label Free ◽  
Impedance Sensing ◽  
Fully Integrated ◽  
Impedance Response ◽  
Strength Dependence

A method for label-free electrical impedance sensing of DNA is proposed, and experimentally demonstrated using a micro Electrical Impedance Spectroscopy (µ- EIS) device. The method features not only the detection of DNA without any labelling, but also the control of the conformation that would enhance the electrical impedance signal. In order to conduct semiautomated measurements controlled by an external PC, a microfluidic chip made of a silicone elastomer of polydimethylsiloxane (PDMS), a measurement chip embedded with micro-electrodes, and a micropump chip are fully integrated in the µ-EIS device. The µ-EIS device is capable of detecting DNA concentrations of a few nM in aqueous solution of a few pL in volume by virtue of the conformation-enhanced nonlinear impedance response. As a first demonstration of conformational-change-induced DNA analysis, the frequency and the electric field strength dependence of various lengths of DNA are evaluated.

scholarly journals Microwave Assisted Sol-Gel Synthesis of Silica-Spider Silk Composites

Molecules ◽  
2019 ◽  
Vol 24 (14) ◽  
pp. 2521
Author(s):  
Abul Bashar Mohammad Giasuddin ◽  
David W. Britt
Keyword(s):  
Aqueous Solution ◽  
Infrared Spectroscopy ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Spider Silk ◽  
Sol Gel ◽  
Silk Protein ◽  
Acidic Aqueous Solution ◽  
Silica Nanocomposites ◽  
Spider Silk Protein

This study introduces a simple and environmentally friendly method to synthesize silica-protein nanocomposite materials using microwave energy to solubilize hydrophobic protein in an aqueous solution of pre-hydrolyzed organo- or fluoro-silane. Sol-gel functionality can be enhanced through biomacromolecule incorporation to tune mechanical properties, surface energy, and biocompatibility. Here, synthetic spider silk protein and organo- and fluoro-silane precursors were dissolved and mixed in weakly acidic aqueous solution using microwave technology. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) images revealed the formation of spherical nanoparticles with sizes ranging from 100 to 500 nm depending, in part, on silane fluoro- or organo-side chain chemistry. The silane-protein interaction in the nanocomposite was assessed through infrared spectroscopy. Deconvoluted ATR-FTIR (Attenuated total reflectance Fourier-transform infrared spectroscopy) spectra revealed silane chemistry-specific conformational changes in the protein-silane nanocomposites. Relative to microwave-solubilized spider silk protein, the β structure content increased by 14% in the spider silk-organo-silica nanocomposites, but decreased by a net 20% in the spider silk-fluoro-silica nanocomposites. Methods of tuning the secondary structures, and in particular β-sheets that are the cross-linking moieties in spider silks and other self-assembling fibrillar proteins, may provide a unique means to promote protein interactions, favor subsequent epitaxial growth process, and enhance the properties of the protein-silane nanocomposites.

pH- and chaotropic anion-induced conformational changes of tertiary amine-containing binary heterografted star molecular bottlebrushes in aqueous solution

2021 ◽  
Author(s):  
Ethan W. Kent ◽  
Evan M. Lewoczko ◽  
Bin Zhao
Keyword(s):  
Aqueous Solution ◽  
Conformational Changes ◽  
Tertiary Amine ◽  
Ph Changes ◽  
Chaotropic Anions ◽  
Shape Transitions

Three-arm star-shaped, tertiary-amine-containing bottlebrushes exhibit star-globule shape transitions in response to pH changes and addition of sufficiently strong chaotropic anions.

Oligopeptide-porphyrin interactions studied by circular dichroism spectroscopy: the effect of metalloporphyrin axial ligands on peptide matrix conformation

2008 ◽  
Vol 12 (12) ◽  
pp. 1270-1278 ◽  
Author(s):  
Vladimír Setnička ◽  
Jan Hlaváček ◽  
Marie Urbanová
Keyword(s):  
Aqueous Solution ◽  
Circular Dichroism ◽  
Conformational Changes ◽  
Helical Conformation ◽  
Compact Structure ◽  
Axial Ligands ◽  
Metal Derivatives ◽  
Derivatives Of ◽  
Circular Dichroïsm ◽  
Β Sheet

Vibrational (VCD) and electronic circular dichroism (ECD) spectroscopies were used to investigate non-covalent interactions between the cationic tripeptide L-lysyl-L-alanyl-L-alanine (KAA) and the anionic porphyrin meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) in aqueous solution. Also studied were the interactions between KAA and the three metal derivatives of TPPS (copper(II), iron(III), and manganese(III)), each of which has a different number of axial ligands. VCD spectra in the amide I' ( C = O stretching vibration) region are extremely sensitive to peptide conformation, and, consequently, provide direct information about the conformational changes of host oligopeptide matrices caused by electrostatic interaction with guest porphyrin molecules. We found that pure KAA adopts a left-handed polyproline II (PPII) helical conformation when dissolved in aqueous solution at near-neutral pH values. When mixed with metal-free TPPS under the same conditions, VCD intensities were markedly reduced in the amide I' region and a new negative band was observed at 1634 cm−1; both findings indicating the transition of the PPII conformation into a less compact structure having similarities to β-sheet, herein termed a β-sheet-like conformation. In the case of the metal derivatives of TPPS studied, only variations in the VCD intensities in the amide I' region were observed. Compared to the results for pure KAA, the binding of Cu (II) TPPS , which has no axial ligand, resulted in the greatest decrease in amide I' VCD intensity. Nevertheless, the shape of a VCD spectrum characteristic for a PPII conformation was maintained, thereby indicating the presence of an “extended” PPII conformation in the Cu (II) TPPS -KAA complex. Conversely, Mn (III) TPPS , which has two axial ligands, did not significantly affect the PPII conformation of KAA in the Mn (III) TPPS -KAA complex. The effects of the metalation and axial ligation of TPPS on the conformation of KAA in peptide-porphyrin complexes are discussed, together with the results of our ECD study.

scholarly journals A Facile Synthetic Route to Amphiphilic Poly(Meta-Phenylene Ethynylene) and Poly(Meta-Phenylene Ethynylene)-Block-Polyisocyanide Using a Single Catalyst

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 936 ◽  
Author(s):  
Chonglong Li ◽  
Xunhui Xu ◽  
Lei Xu ◽  
Na Liu
Keyword(s):  
Conformational Changes ◽  
Mixed Solvents ◽  
Cotton Effect ◽  
Optically Active ◽  
Amphiphilic Block Copolymers ◽  
Helical Conformation ◽  
Mixing Ratio ◽  
Phenylene Ethynylene ◽  
Synthetic Route ◽  
Cotton Effects

An optically active, amphiphilic meta-phenylene ethynylene (m-PE) bearing a chiral amide pendant was designed and synthesized. Living polymerization of m-PE using alkyne-Pd(II) as the initiator afforded well-defined poly(meta-phenylene ethynylene) (m-PPE). These m-PPEs were found to have a stable helical conformation in THF, 1,4-dioxane, and CH3CN and showed split Cotton effects over the range of 245–400 nm. The positive first Cotton effect was observed at a wavelength of approximately 308 nm, and the negative second Cotton effect was observed at a wavelength of approximately 289 nm. The m-PPEs exhibited helical conformational changes in different mixed solvents and showed effective solvent-dependent helix inversion in CHCl3/THF solutions. The sign of the Cotton effect of m-PPE was inverted at 25 °C by varying the mixing ratio of THF and CHCl3. Finally, amphiphilic poly(meta-phenylene ethynylene)-block-polyisocyanide containing hydrophilic PPE and hydrophobic PPI segments were facilely prepared using Pd(II)-terminated m-PPE as the macroinitiator. This block copolymer can self-assemble into well-defined spherical nanostructures in a selective THF/CH3OH solution. This efficient polymerization will open up enormous opportunities for the preparation of functional amphiphilic block copolymers in a wide variety of fields.

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