scholarly journals Electrospinning and Post-Spun Chain Conformations of Synthetic, Hydrophobic Poly(α-amino acid)s

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 327 ◽  
Author(s):  
Kesavan Devarayan ◽  
Souta Nakagami ◽  
Shuichi Suzuki ◽  
Ichiro Yuki ◽  
Kousaku Ohkawa
Keyword(s):  
Amino Acid ◽  
Trifluoroacetic Acid ◽  
Average Molecular Weight ◽  
Helical Structure ◽  
Degree Of Polymerization ◽  
Random Coil ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Acid Anhydrides ◽  
Chain Conformations

Electrospinning and post-spun conformations of hydrophobic poly(α-amino acid)s are described in this study. The poly(α-amino acid)s, poly(Gly), poly(l-Ala), poly(l-Val), and poly(l-Leu) were synthesized via corresponding N-carboxy-α-amino acid anhydrides. The average molecular weight and degree of polymerization of these polymers were determined by N-terminus labeling using 2,4-dinitrofluorobenzene and by viscometry in the case of poly(Gly). These poly(α-amino acid)s were electrospun from trifluoroacetic acid or trifluoroacetic acid/dichloromethane solutions. The FT-IR spectroscopy and wide-angle X-ray diffraction indicated that the electrospun poly(l-Ala) and poly(l-Leu) fibers predominantly adopts α-helical structure, whereas poly(l-Val) and poly(Gly) fibers exhibited mainly β-strand and random coil structures, respectively.

High Functional PET Sericin Composite Fabric

2012 ◽  
Vol 430-432 ◽  
pp. 49-52
Author(s):  
Gang Xian Zhang ◽  
Xiao Hua Shi ◽  
Wei Hu ◽  
Feng Xiu Zhang ◽  
Da Yang Wu
Keyword(s):  
High Pressure ◽  
Glycidyl Ether ◽  
Air Permeability ◽  
Sucrose Ester ◽  
Random Coil ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pet Fabric ◽  
Initial Modulus ◽  
Ft Ir

Though poly(ethyleneteraphthalate)(PET) fabrics have high initial modulus, outstanding creasability and wash-well character, but its hydrophilicity and biocompatibility are very poor. In this paper, the PET fabric was encased sucrose ester at high pressure and high temperature to endue it enough hydroxyl to grafting protein. The sericin was grafted on PET fabric by sucrose eater glycidyl ether (SEGE). The FT-IR spectra showed that sericin was grafted on PET fabric, and the structure of sericin was random coil conformation. X-ray diffraction spectra showed the structure of PET fiber did not changed. DSC showed the thermostability increased a little. After the PET fabric grafted with sericin, the hydrophilicity of PET sericin composite fabric was improved greatly, the cockle elasticity kept well, and the broken strength in creased a little. Certainly, the whiteness and air permeability decreased a little. The PET sericin composite fabric was high functional.

Studies on polyimides containing thermoplastic-thermosetting merged segments

2014 ◽  
Vol 34 (5) ◽  
pp. 451-457 ◽  
Author(s):  
Yogesh S. Patel
Keyword(s):  
Average Molecular Weight ◽  
Bulk Polymerization ◽  
Degree Of Polymerization ◽  
Diels Alder ◽  
Mechanical And Electrical Properties ◽  
Glass Fiber Reinforced ◽  
Elemental Analyses ◽  
Ft Ir ◽  
A Chain

Abstract Polyimides (PIs) containing thermoplastic and thermosetting merged segments in a chain were developed via Diels-Alder (DA) polymerization of a bisfuran (BF), namely 2,5-bis(furan-2-ylmethylcarbamoyl)terephthalic acid and bismaleimides (BMI1 and BMI2). The intermediate DA polyadducts thus obtained, DAA1 and DAA2, were aromatized and imidized (cyclized) through carboxylic and amide groups in the presence of acetic anhydride, to afford PI1 and PI2. Synthesized DA polyadducts and PIs were characterized by elemental analysis, spectral features, number average molecular weight (Mn), degree of polymerization (Dp) and thermal analysis. Bulk polymerization was also carried out. The obtained bulk polymerization products (BPP1 and BPP2) were characterized by elemental analyses and Fourier transform infrared spectroscopy (FT-IR) analysis. The “in situ” void-free glass fiber reinforced composites GFRC1 and GFRC2 were prepared from the produced system and characterized by chemical, mechanical and electrical analysis. All of the composites depicted good mechanical and electrical properties and good resistance to organic solvents and mineral acids.

Determination of Molecular Weight and Structure Characterization of Canna Amylose Purified Using the Method of n-Butanol Recrystallization

2012 ◽  
Vol 554-556 ◽  
pp. 1216-1222
Author(s):  
Hai Xin Shi ◽  
Yan Zhen Yin ◽  
Xiao Xi Hu ◽  
Shu Fei Jiao
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Granule Surface ◽  
Chemical Groups ◽  
Ubbelohde Viscometer

The canna amylose (CAM) was separated from canna starch grown in China and purified both using the method of n-butanol recrystallization. The purity, morphology, spectral properties and molecular weight of CAM were characterized by ultraviolet and visible spectrophotometer (UV/Vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR) and Ubbelohde viscometer. Maximum absorption wavelength of the purified CAM (635－638 nm) and it’s blue values (BV) (1.167 ± 0.209) prove that the purification of the CAM by n-butanol recrystallization was successfully carried out. The SEM results show that CAM granule surface become rougher and the CAM granule size become smaller than that of canna starch. The XRD results suggest that most of CAM granule is amorphous. And the FT-IR results show that the basic chemical groups of canna starch are also presented in CAM. However, the amorphous area of CAM is increased. The intrinsic viscosity and viscosity-average molecular weight of CAM is 78.5 mL/g and 1.65×105, respectively.

scholarly journals Linear Dextrin as Potential Insulin Delivery System: Effect of Degree of Polymerization on the Physicochemical Properties of Linear Dextrin–Insulin Inclusion Complexes

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4187
Author(s):  
Huifang Xie ◽  
Xin Ma ◽  
Wenbin Lin ◽  
Shiting Dong ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Inclusion Complexes ◽  
Aqueous Ethanol ◽  
Potato Starch ◽  
Degree Of Polymerization ◽  
X Ray Diffraction ◽  
System Effect ◽  
X Ray ◽  
Ft Ir ◽  
Ir Analysis ◽  
Differential Solubility

In the current study, linear dextrin (LD) was prepared using waxy potato starch debranched with pullulanase, which has attracted immense interest in the food, pharmaceutical, and cosmetic industries as a versatile ingredient. Various LDs were separated on the basis of their differential solubility in aqueous/ethanol solutions of different volumetric ratios. Three LD products—LD Fabrications with 40% ethanol (F-40); LD Fabrications with 50% ethanol (F-50); and LD Fabrications with 60%, 70%, and 80% ethanol (F-M)—were obtained with an average degree of polymerization (DP) values of 31.44, 21.84, and 16.10, respectively. The results of Fourier transform infrared spectroscopy (FT-IR) analysis revealed that the reaction mainly involved hydrogen bonding and a hydrophobic interaction between LD and insulin in the process of inclusion complex formation. X-ray diffraction (XRD) results indicated that insulin was encapsulated in LD. The results of circular dichroism (CD) showed that the changes in the secondary structure of insulin were negligible during the release from the inclusion complexes. The order of encapsulation capacity is as follows: the complex composed of F-M and insulin (F-M-INS) > the complex composed of LD and insulin (LD-INS) > the complex composed of F-50 and insulin (F-50-INS) > and the complex composed of F-40 and insulin (F-40-INS). F-M-INS inclusion complexes showed a better effect on reducing the release of insulin in gastric juice and promoting the release of insulin in intestinal juice and blood plasma than LD-INS.

The Study of Existential State of Protein in Protein/Montmorillonite Complexes

2011 ◽  
Vol 194-196 ◽  
pp. 1647-1651
Author(s):  
Ying Hai Lv ◽  
Gui Jiang Li ◽  
Li Qiang Cui ◽  
Hua Xiao Yan ◽  
Shi Xue Zhou
Keyword(s):  
Interlayer Space ◽  
Random Coil ◽  
Infrared Spectrometry ◽  
X Ray Diffraction ◽  
Fourier Transform Infrared Spectrometry ◽  
X Ray ◽  
Ft Ir ◽  
Loading Amount ◽  
Α Helix ◽  
Structure Of Proteins

The existential state of protein in complexes directly affects the performance and applications of the composite materials. The interlayer space changes of montmorillonite in the protein / montmorillonite (MMT) composite were identified by X-ray diffraction (XRD). And the interaction between protein and MMT were analyzed by Fourier transform infrared spectrometry (FT-IR) and UV/vis spectrophotometry. The loading amount of bovine serum albumin (BSA) onto MMT was calculated from the TG data. The types of adsorption isotherm of BSA onto montmorillonite were analyzed. From the above analysis, it can be concluded that the structure of proteins in the montmorillonite interlayers has been changed, and the hydrogen bond and Van der Waals force between the BSA molecules and montmorillonite crystal layers are intensified. The α-helix content of BSA molecules reduces while random coil increases. The protein shows a state of being squashed.

A samarium hybrid with porphyrin and amino acid as mixed ligands: Electrochemical and photophysical properties

2015 ◽  
Vol 19 (10) ◽  
pp. 1140-1146 ◽  
Author(s):  
Yun-Peng Pei ◽  
Jian-Gen Huang ◽  
Hua-Long Chen ◽  
Han-Mao Kuang ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Amino Acid ◽  
Hydrothermal Reaction ◽  
Photophysical Properties ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixed Ligands ◽  
Porphyrin Macrocycle ◽  
Ft Ir ◽  
Emission Quantum Yield

A samarium hybrid with porphyrin and amino acid as mixed ligands {[Sm(His)(H2O)][Sm(H3O)3](H2TPPS)2} • 5H2O (1) (His = histidine; H6TPPS = tetra(4-sulfonatophenyl)porphyrin) has been synthesized via a hydrothermal reaction and characterized by single-crystal X-ray diffraction. Compound 1is crystallized in the space group [Formula: see text] of the triclinic system. Compound 1is characteristic of a three-dimensional (3-D) open framework with the samarium ions in two types of coordinating environments and a saddle-distorted nonplanar porphyrin macrocycle. Compound 1 exhibits fluorescence in the red region. The fluorescence lifetime of 1 is 15.65 ns and the emission quantum yield is 4.1%. The CV/DPV, UV-vis and FT-IR are also reported in detail.

Structure-forming units of amino acid maleates. Case study ofL-valinium hydrogen maleate

2016 ◽  
Vol 72 (1) ◽  
pp. 160-163 ◽  
Author(s):  
Denis Rychkov ◽  
Sergey Arkhipov ◽  
Elena Boldyreva
Keyword(s):  
Amino Acid ◽  
Density Functional ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Bulk Powder ◽  
Ft Ir ◽  
The Stability ◽  
Almost All

A new salt of L-valinium hydrogen maleate was used as an example to study structure-forming units in amino acid maleates. This compound was crystallized, its structure solved from single-crystal X-ray diffraction data, and the phase purity of the bulk powder sample confirmed by X-ray powder diffraction and FT–IR spectra. The stability of the new salt was analyzed using density functional theory andPIXELcalculations with focus on theC22(12) structure-forming crystallographic motif. This motif was of particular interest as it is common for almost all maleates. The exceptionally high ability of maleic acid to form salts with various amino acids was rationalized.

Series of sequential polypeptides containing lysine or arginine: Preparation and characterization

1988 ◽  
Vol 53 (1) ◽  
pp. 145-156 ◽  
Author(s):  
Jana Pírková ◽  
Svetlana Churkina ◽  
Vladimír Gut ◽  
Ivo Frič ◽  
Karel Bláha
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Peptide Synthesis ◽  
Average Molecular Weight ◽  
Basic Amino Acid ◽  
Cd Spectra ◽  
Active Esters ◽  
Marked Tendency

The sequential polypeptides (Lys-Ala)n, (Lys-Ala-Ala)n, (Lys-Ala-Ala-Ala)n, (Lys-Leu-Ala)n, (Lys-Leu-Ala-Ala)n, (Lys-Leu-Ala-Ala-Ala)n, (Lys-Ala-Leu)n, (Lys-Ala-Leu-Ala)n, (Orn-Leu-Ala)n,(Arg-Ala-Ala)n, (Arg-Leu-Ala)n, (Arg-Leu-Ala-Ala)n, (Arg-Ala-Leu)n, and (Arg-Ala-Leu-Ala)n were synthesized by polymerization of active esters (1-succinimidyl or pentafluorophenyl) of the corresponding Nα-deblocked monomers. The monomers were prepared using the usual methods of peptide synthesis in solution. Upon dialysis, the average molecular weight of the polymer was 6 000-9 000 as determined by sedimentation in ultracentrifuge. Polypeptides, containing leucine in addition to the basic amino acid, showed a marked tendency to aggregation. CD spectra of the products were measured for characterization.

Axially Chiral Bis(α-amino Acid)s and Their Deamino Analogues. Synthesis and Configurational Assignment

1998 ◽  
Vol 63 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Miloš Tichý ◽  
Luděk Ridvan ◽  
Miloš Buděšínský ◽  
Jiří Závada ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nmr Spectra ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
X Ray ◽  
Configurational Assignment ◽  
Symmetry Properties ◽  
Axially Chiral ◽  
Polymeric Structures

The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.

scholarly journals Primary- and secondary-structural analysis of a unique prokaryotic metallothionein from a Synechococcus sp. cyanobacterium

1988 ◽  
Vol 251 (3) ◽  
pp. 691-699 ◽  
Author(s):  
R W Olafson ◽  
W D McCubbin ◽  
C M Kay
Keyword(s):  
Amino Acid ◽  
Metal Binding ◽  
Helical Structure ◽  
Basic Amino Acid ◽  
Cysteine Residues ◽  
Amino Acid Residues ◽  
C Terminus ◽  
Empirical Relations ◽  
Heavy Metal Binding ◽  
Synechococcus Sp

Biochemical and physiological studies of Synechococcus cyanobacteria have indicated the presence of a low-Mr heavy-metal-binding protein with marked similarity to eukaryotic metallothioneins (MTs). We report here the characterization of a Synechococcus prokaryotic MT isolated by gel-permeation and reverse-phase chromatography. The large number of variants of this molecule found during chromatographic separation could not be attributed to the presence of major isoproteins as assessed by amino acid analysis and amino acid sequencing of isoforms. Two of the latter were shown to have identical primary structures that differed substantially from the well-described eukaryotic MTs. In addition to six long-chain aliphatic residues, two aromatic residues were found adjacent to one another near the centre of the molecule, making this the most hydrophobic MT to be described. Other unusual features included a pair of histidine residues located in repeating Gly-His-Thr-Gly sequences near the C-terminus and a complete lack of association of hydroxylated residues with cysteine residues, as is commonly found in eukaryotes. Similarly, aside from a single lysine residue, no basic amino acid residues were found adjacent to cysteine residues in the sequence. Most importantly, sequence alignment analyses with mammalian, invertebrate and fungal MT sequences showed no statistically significant homology aside from the presence of Cys-Xaa-Cys structures common to all MTs. On the other hand, like other MTs, the prokaryotic molecule appears to be free of alpha-helical structure but has a considerable amount of beta-structure, as predicted by both c.d. measurements and the Chou & Fasman empirical relations. Considered together, these data suggested that some similarity between the metal-thiolate clusters of the prokaryote and eukaryote MTs may exist.

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