Browse
Submit Data
Databases
API
Help

Dataset Information

10 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Elucidation of the structure of poly(γ-benzyl-l-glutamate) nanofibers and gel networks in a helicogenic solvent.

ABSTRACT: The synthesis, characterization, self-assembly, and gel formation of poly(γ-benzyl-l-glutamate) (PBLG) in a molecular weight range from ca. 7,000-100,000 g/mol and with narrow molecular weight distribution are described. The PBLG is synthesized by the nickel-mediated ring-opening polymerization and is characterized by size-exclusion chromatography coupled with multiple-angle laser light scattering, NMR, and Fourier transform infrared spectroscopy. The self-assembly and thermoreversible gel formation in the helicogenic solvent toluene is investigated by transmission electron microscopy, atomic force microscopy, small-angle X-ray scattering, and synchrotron powder X-ray diffraction. At concentrations significantly below the minimum gelation concentration, spherical aggregates are observed. At higher concentrations, gels are formed, which show a 3D network structure composed of nanofibers. The proposed self-assembly mechanism is based on a distorted hexagonal packing of PBLG helices parallel to the axis of the nanofiber. The gel network forms due to branching and rejoining of bundles of PBLG nanofibers. The network exhibits uniform domains with a length of 200 ± 42 nm composed of densely packed PBLG helices.

SUBMITTER: Niehoff A

PROVIDER: S-EPMC3669512 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

The structure of PghL hydrolase bound to its substrate poly-γ-glutamate.

Project description:The identification of new strategies to fight bacterial infections in view of the spread of multiple resistance to antibiotics has become mandatory. It has been demonstrated that several bacteria develop poly-γ-glutamic acid (γ-PGA) capsules as a protection from external insults and/or host defence systems. Among the pathogens that shield themselves in these capsules are Bacillus anthracis, Francisella tularensis and several Staphylococcus strains. These are important pathogens with a profound influence on human health. The recently characterised γ-PGA hydrolases, which can dismantle the γ-PGA-capsules, are an attractive new direction that can offer real hope for the development of alternatives to antibiotics, particularly in cases of multidrug resistant bacteria. We have characterised in detail the cleaving mechanism and stereospecificity of the enzyme PghL (previously named YndL) from Bacillus subtilis encoded by a gene of phagic origin and dramatically efficient in degrading the long polymeric chains of γ-PGA. We used X-ray crystallography to solve the three-dimensional structures of the enzyme in its zinc-free, zinc-bound and complexed forms. The protein crystallised with a γ-PGA hexapeptide substrate and thus reveals details of the interaction which could explain the stereospecificity observed and give hints on the catalytic mechanism of this class of hydrolytic enzymes.

| S-EPMC6506827 | biostudies-literature

Solvent Effects on Morphology and Electrical Properties of Poly(3-hexylthiophene) Electrospun Nanofibers.

Project description:Herein, poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofiber-based organic field-effect transistors were successfully prepared by coaxial electrospinning technique with P3HT as the core polymer and poly(methyl methacrylate) (PMMA) as the shell polymer, followed by extraction of PMMA. Three different solvents for the core polymer, including chloroform, chlorobenzene and 1,2,4-trichlorobenzene, were employed to manipulate the morphologies and electrical properties of P3HT electrospun nanofibers. Through the analyses from dynamic light scattering of P3HT solutions, polarized photoluminescence and X-ray diffraction pattern of P3HT electrospun nanofibers, it is revealed that the P3HT electrospun nanofiber prepared from the chloroform system displays a low crystallinity but highly oriented crystalline grains due to the dominant population of isolated-chain species in solution that greatly facilitates P3HT chain stretching during electrospinning. The resulting high charge-carrier mobility of 3.57 × 10-1 cm2·V-1·s-1 and decent mechanical deformation up to a strain of 80% make the P3HT electrospun nanofiber a promising means for fabricating stretchable optoelectronic devices.

| S-EPMC6780587 | biostudies-literature

Microbial production and chemical transformation of poly-γ-glutamate.

Project description:Poly-γ-glutamate (PGA), a novel polyamide material with industrial applications, possesses a nylon-like backbone, is structurally similar to polyacrylic acid, is biodegradable and is safe for human consumption. PGA is frequently found in the mucilage of natto, a Japanese traditional fermented food. To date, three different types of PGA, namely a homo polymer of D-glutamate (D-PGA), a homo polymer of L-glutamate (L-PGA), and a random copolymer consisting of D- and L-glutamate (DL-PGA), are known. This review will detail the occurrence and physiology of PGA. The proposed reaction mechanism of PGA synthesis including its localization and the structure of the involved enzyme, PGA synthetase, are described. The occurrence of multiple carboxyl residues in PGA likely plays a role in its relative unsuitability for the development of bio-nylon plastics and thus, establishment of an efficient PGA-reforming strategy is of great importance. Aside from the potential applications of PGA proposed to date, a new technique for chemical transformation of PGA is also discussed. Finally, some techniques for PGA and its derivatives in advanced material technology are presented.

| S-EPMC3815933 | biostudies-literature

Characterization of poly-gamma-glutamate hydrolase encoded by a bacteriophage genome: possible role in phage infection of Bacillus subtilis encapsulated with poly-gamma-glutamate.

Project description:Some Bacillus subtilis strains, including natto (fermented soybeans) starter strains, produce a capsular polypeptide of glutamate with a gamma-linkage, called poly-gamma-glutamate (gamma-PGA). We identified and purified a monomeric 25-kDa degradation enzyme for gamma-PGA (designated gamma-PGA hydrolase, PghP) from bacteriophage PhiNIT1 in B. subtilis host cells. The monomeric PghP internally hydrolyzed gamma-PGA to oligopeptides, which were then specifically converted to tri-, tetra-, and penta-gamma-glutamates. Monoiodoacetate and EDTA both inhibited the PghP activity, but Zn(2+) or Mn(2+) ions fully restored the enzyme activity inhibited by the chelator, suggesting that a cysteine residue(s) and these metal ions participate in the catalytic mechanism of the enzyme. The corresponding pghP gene was cloned and sequenced from the phage genome. The deduced PghP sequence (208 amino acids) with a calculated M(r) of 22,939 was not significantly similar to any known enzyme. Thus, PghP is a novel gamma-glutamyl hydrolase. Whereas phage PhiNIT1 proliferated in B. subtilis cells encapsulated with gamma-PGA, phage BS5 lacking PghP did not survive well on such cells. Moreover, all nine phages that contaminated natto during fermentation produced PghP, supporting the notion that PghP is important in the infection of natto starters that produce gamma-PGA. Analogous to polysaccharide capsules, gamma-PGA appears to serve as a physical barrier to phage absorption. Phages break down the gamma-PGA barrier via PghP so that phage progenies can easily establish infection in encapsulated cells.

| S-EPMC154523 | biostudies-literature

Poly-γ-S-perillyl-l-glutamate and Poly-γ-S-perillyl-d-glutamate: Diastereomeric Alignment Media Used for the Investigation of the Alignment Process.

Project description:Residual dipolar couplings (RDCs) offer additional information for structure elucidation by NMR spectroscopy. They are measured in anisotropic media, such as lyotropic liquid crystalline phases of polypeptides. Today, some suitable polypeptides are known. Nevertheless, structural influences of these polypeptides on the alignment properties are not really understood. Thus, which influence a chiral side chain has on enantiodiscrimination and whether we can improve the enantiodifferentiation significantly by adding an additional chiral center in the side chain are questions of interest. Therefore, new diastereomeric polypeptide-based alignment media with an additional chiral center in the side chain derived from perillyl alcohol were synthesized and their properties were investigated (secondary structure, liquid crystallinity, etc.). The enantiomers of isopinocampheol and β-pinene were used as model analytes for the study of enantiodiscrimination. Additionally, the usage of 1 H-1 H-RDCs to improve the alignment tensor quality is demonstrated.

| S-EPMC7384199 | biostudies-literature

Arborescent Unimolecular Micelles: Poly(γ-Benzyl l-Glutamate) Core Grafted with a Hydrophilic Shell by Copper(I)-Catalyzed Azide⁻Alkyne Cycloaddition Coupling.

Project description:Amphiphilic copolymers were obtained by grafting azide-terminated polyglycidol, poly(ethylene oxide), or poly(2-hydroxyethyl acrylate) chain segments onto alkyne-functionalized arborescent poly(γ-benzyl l-glutamate) (PBG) cores of generations G1⁻G3 via copper(I)-catalyzed azide⁻alkyne Huisgen cycloaddition (CuAAC) coupling. The alkyne functional groups on the arborescent PBG substrates were either distributed randomly or located exclusively at the end of the chains added in the last grafting cycle of the core synthesis. The location of these coupling sites influenced the ability of the arborescent copolymers to form unimolecular micelles in aqueous environments: The chain end grafting approach provided enhanced dispersibility in aqueous media and favored the formation of unimolecular micelles in comparison to random grafting. This is attributed to a better defined core-shell morphology for the copolymers with end-grafted shell segments. Aqueous solubility also depended on the type of material used for the shell chains. Coupling by CuAAC opens up possibilities for grafting a broad range of polymers on the arborescent substrates under mild conditions.

| S-EPMC6418952 | biostudies-literature

new domain of poly-gamma-glutamate synthase PgsB

Project description: Not available

| S-BSST430 | biostudies-other

The poly-gamma-glutamate of Bacillus subtilis interacts specifically with silver nanoparticles.

Project description:For many years, silver nanoparticles, as with other antibacterial nanoparticles, have been extensively used in manufactured products. However, their fate in the environment is unclear and raises questions. We studied the fate of silver nanoparticles in the presence of bacteria under growth conditions that are similar to those found naturally in the environment (that is, bacteria in a stationary phase with low nutrient concentrations). We demonstrated that the viability and the metabolism of a gram-positive bacteria, Bacillus subtilis, exposed during the stationary phase is unaffected by 1 mg/L of silver nanoparticles. These results can be partly explained by a physical interaction of the poly-gamma-glutamate (PGA) secreted by Bacillus subtilis with the silver nanoparticles. The coating of the silver nanoparticles by the secreted PGA likely results in a loss of the bioavailability of nanoparticles and, consequently, a decrease of their biocidal effect.

| S-EPMC5973573 | biostudies-literature

Crystallization and preliminary crystallographic analysis of poly-gamma-glutamate hydrolase from bacteriophage PhiNIT1.

Project description:Particular Bacillus subtilis strains produce a capsular polypeptide poly-gamma-glutamate (gamma-PGA) that functions as a physical barrier against bacteriophage infection. Bacteriophage PhiNIT1 can infect B. subtilis and produces a novel gamma-PGA hydrolase PghP. PghP was overexpressed, purified and crystallized by the sitting-drop vapour-diffusion method. The crystals diffracted to a resolution of 2.4 A using a synchrotron X-ray source and were found to belong to space group P3(1)21 or P3(2)21.

| S-EPMC2795599 | biostudies-literature

Expression, crystallization and structure elucidation of γ-terpinene synthase from Thymus vulgaris.

Project description:The biosynthesis of γ-terpinene, a precursor of the phenolic isomers thymol and carvacrol found in the essential oil from Thymus sp., is attributed to the activitiy of γ-terpinene synthase (TPS). Purified γ-terpinene synthase from T. vulgaris (TvTPS), the Thymus species that is the most widely spread and of the greatest economical importance, is able to catalyze the enzymatic conversion of geranyl diphosphate (GPP) to γ-terpinene. The crystal structure of recombinantly expressed and purified TvTPS is reported at 1.65 Å resolution, confirming the dimeric structure of the enzyme. The putative active site of TvTPS is deduced from its pronounced structural similarity to enzymes from other species of the Lamiaceae family involved in terpenoid biosynthesis: to (+)-bornyl diphosphate synthase and 1,8-cineole synthase from Salvia sp. and to (4S)-limonene synthase from Mentha spicata.

| S-EPMC4708045 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data