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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gamma-poly(glutamic acid) (gamma-PGA), a hydrophilic and biodegradable polymer, was chosen to modify chitosan matrices to produce a gamma-PGA/chitosan composite biomaterial. Three types of both dense and porous composite matrices containing different amounts of gamma-PGA were fabricated. Chitosan and gamma-PGA matrices were also prepared as controls. Fluorescence staining indicated that chitosan and gamma-PGA were evenly distributed in the composite matrices. SEM micrographs showed that an interconnected porous structure with a pore size of 30-100 microm was present in all porous matrices except the gamma-PGA ones. By increasing the percentage of gamma-PGA from 0% to 20%, the swelling ratio of the matrices was enhanced from 1.6 to 3.2. Similarly, the contact angle of the matrices decreased from 113 degrees to 94 degrees . These data suggested that the surface hydrophilicity, water absorption rate, and swelling ratio were improved by adding gamma-PGA to the matrices. Additionally, the mechanical strength of the porous gamma-PGA/chitosan matrices was about 25-50%, higher than that of the unmodified chitosan matrices. The composite matrices were also examined and found to be an appropriate environment for cell attachment and proliferation. The cell density on the 20% gamma-PGA-modified matrices was almost triple that on the unmodified chitosan matrices on day 5. In summary, the gamma-PGA/chitosan composite matrices, due to their better hydrophilic, cytocompatible, and mechanical properties, are very promising biomaterials for tissue engineering applications.
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PMID:Preparation of gamma-PGA/chitosan composite tissue engineering matrices. 1587 66

Poly(gamma-glutamic acid)-sulfonate (gamma-PGA-S) hydrogel, with fibroblast growth factor (FGF)-2 activity was investigated as a novel, next-generation tissue-engineering material. gamma-PGA-net-gamma-PGA-S72 (S72-netgel) was prepared with gamma-PGA-S and gamma-PGA-S72 (72% sulfonated gamma-PGA) to provide the high mobility of gamma-PGA-S72 for FGF-2 activity. Cell adhesion and proliferation activities were evaluated on gamma-PGA and gamma-PGA-S hydrogels along with S72-netgels. Both cell adhesion and proliferation activities of gamma-PGA and gamma-PGA-S hydrogels were low. In contrast, S72-netgels had high cell adhesion and proliferation activities, because of their low swelling ratios and high sulfonic acid group concentrations. Furthermore, S72-netgels had high FGF-2 activity, because gamma-PGA-S72 retained FGF-2 activity when incorporated into S72-netgels. S72-netgels should be useful as next-generation tissue-engineering material containing FGF-2 activity.
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PMID:Novel functional biodegradable polymer. III. The construction of poly(gamma-glutamic acid)-sulfonate hydrogel with fibroblast growth factor-2 activity. 1590 Jun 8

In the study, poly(gamma-glutamic acid) (gamma-PGA) and poly(lactide) (PLA) were used to synthesize block copolymers via a simple coupling reaction between gamma-PGA and PLA to prepare self-assembled nanoparticles. For the potential of targeting liver cancer cells, galactosamine was further conjugated on the prepared nanoparticles as a targeting moiety. gamma-PGA, a water-soluble, biodegradable, and non-toxic compound, was produced by microbial fermentation (Bacillus licheniformis, ATCC 9945a) and then was hydrolyzed. The hydrolyzed gamma-PGA with a molecular weight of 4 kDa and a polydispersity of 1.3 was used, together with PLA (10 kDa, polydispersity 1.1), to synthesize block copolymers. The prepared nanoparticles had a mean particle size of about 140 nm with a zeta potential of about -20 mV. The results obtained by the TEM and AFM examinations showed that the morphology of the prepared nanoparticles was spherical in shape with a smooth surface. In the stability study, no aggregation or precipitation of nanoparticles was observed during storage for up to 1 month, as a result of the electrostatic repulsion between the negatively charged nanoparticles. With increasing the galactosamine content conjugated on the rhodamine-123-containing nanoparticles, the intensity of fluorescence observed in HepG2 cells increased significantly. Additionally, the intensity of fluorescence observed in HepG2 cells incubated with the nanoparticles with or without galactosamine conjugated increased approximately linearly with increasing the duration of incubation. In contrast, there was no fluorescence observed in Hs68 cells (without ASGP receptors) incubated with the nanoparticles with galactosamine conjugated. The aforementioned results indicated that the galactosylated nanoparticles prepared in the study had a specific interaction with HepG2 cells via ligand-receptor recognition.
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PMID:Preparation of nanoparticles composed of poly(gamma-glutamic acid)-poly(lactide) block copolymers and evaluation of their uptake by HepG2 cells. 1591 30

Adsorption of proteins onto film surfaces built up layer by layer from oppositely charged polyelectrolytes is a complex phenomenon, governed by electrostatic forces, hydrogen bonds, and hydrophobic interactions. The amounts of the interacting charges, however, both in polyelectrolytes and in proteins adsorbed on such films are a function of the pH of the solution. In addition, the number and the accessibility of free charges in proteins depend on the secondary structure of the protein. The subtle interplay of all these factors determines the adsorption of the proteins onto the polyelectrolyte film surfaces. We investigated the effect of these parameters for polyelectrolyte films built up from weak "protein-like" polyelectrolytes (i.e., polypeptides), poly(L-lysine) (PLL), and poly(glutamic acid) (PGA) and for the adsorption of human serum albumin (HSA) onto these films in the pH range 3.0-10.5. It was found that the buildup of the polyelectrolyte films is not a simple function of the pure charges of the individual polyelectrolytes, as estimated from their respective pKa values. The adsorption of HSA onto (PLL/PGA)n films depended strongly on the polyelectrolyte terminating the film. For PLL-terminated polyelectrolyte films, at low pH, repulsion, as expected, is limiting the adsorption of HSA (having net positive charge below pH 4.6) since PLL is also positively charged here. At high pH values, an unexpected HSA uptake was found on the PGA-ending films, even when both PGA and HSA were negatively charged. It is suggested that the higher surface rugosity and the decrease of the alpha-helix content at basic pH values (making accessible certain charged groups of the protein for interactions with the polyelectrolyte film) could explain this behavior.
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PMID:Human serum albumin self-assembly on weak polyelectrolyte multilayer films structurally modified by pH changes. 1598 3

Amphiphilic poly(gamma-glutamic acid) (gamma-PGA) was prepared by the introduction of L-phenylalanine ethylester (L-PAE) as a side chain. This gamma-PGA-graft-L-PAE formed monodispersed nanoparticles in water. The particle size of the gamma-PGA nanoparticles could be controlled by the degree of L-PAE grafting. The hydrolytic degradation and enzymatic degradation by gamma-glutamyl transpeptidase (gamma-GTP) of these gamma-PGA nanoparticles was studied by gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The hydrolysis ratio of gamma-PGA was found to decrease upon increasing the hydrophilicity of the gamma-PGA. The degradation of the gamma-PGA backbone by gamma-GTP resulted in a dramatic change in nanoparticle morphology. With increasing time, the gamma-PGA nanoparticles reduced in size and finally disappeared completely.Time-course of the changes in the morphology of the gamma-PGA nanoparticles following incubation with gamma-glutamyl transpeptidase.
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PMID:In vitro enzymatic degradation of nanoparticles prepared from hydrophobically-modified poly(gamma-glutamic acid). 1599 Dec 16

Solid-state fermentations (SSF), using swine manure as the basis of a solid substrate, were carried out for high yield of poly-gamma-glutamic acid (gamma-PGA) by Bacillus subtilis CCTCC202048. Fermentation medium and process parameters were optimized through three orthogonal array designs. The optimal medium consisted of 62.3% (w/w, dry weight basis) swine manure, 25.0% soybean cake, 5.0% wheat bran, 5.0% glutamic acid, 2.5% citric acid and 0.2% MnSO4.H2O. The optimal process parameters were 15.0 g medium with initial moisture content 60% and initial pH 9.0 in 250 ml flask, inoculation at mid-log phase with a 4% inoculum level and cultivation for 48 h at 37 degrees C. The average-PGA yield (6.0%) in triplicate under optimal conditions was obtained on the laboratory scale while it was 4.5% at compost experiment. These would lay a foundation for lessening the pollution of swine manure, increasing fertilizer efficiency and exploring a late-model organic fertilizer that retains water and nutrients.
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PMID:High yield of poly-gamma-glutamic acid from Bacillus subtilis by solid-state fermentation using swine manure as the basis of a solid substrate. 1608 66

Biofilms are communities of microbial cells that are encased in a self-produced, polymeric matrix and are adherent to a surface. For several species of bacteria, an enhanced ability to form biofilms has been linked with an increased capability to produce exopolymers. To identify exopolymers of Bacillus subtilis that can contribute to biofilm formation, we transferred the genetic determinants that control exopolymer production from a wild, exopolymer-positive strain to a domesticated, exopolymer-negative strain. Mapping these genetic determinants led to the identification of gamma-poly-dl-glutamic acid (gamma-PGA) as an exopolymer that increases biofilm formation, possibly through enhancing cell-surface interactions. Production of gamma-PGA by Bacillus subtilis was known to be dependent on the two-component regulator ComPA; this study highlighted the additional dependence on the DegS-DegU, DegQ and SwrA regulator proteins. The inability of the domestic strain of B. subtilis to produce gamma-PGA was mapped to two base pairs; a single base pair change in the promoter region of degQ and a single base pair insertion in the coding region of swrA. Introduction of alleles of degQ and swrA from the wild strain into the domestic strain was sufficient to allow gamma-PGA production. In addition to controlling gamma-PGA production, ComPA and DegSU were also shown to activate biofilm formation through an as yet undefined pathway. The identification of these regulators as affecting gamma-PGA production and biofilm formation suggests that these processes are regulated by osmolarity, high cell density and phase variation.
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PMID:Defining the genetic differences between wild and domestic strains of Bacillus subtilis that affect poly-gamma-dl-glutamic acid production and biofilm formation. 1609 Oct 50

The objective of the present study was to prepare nanoparticles composed of poly(gamma-glutamic acid) (gamma-PGA) and l-phenylalanine ethylester (l-PAE) in order to evaluate the possibility of using these nanoparticles as protein carriers. Novel amphiphilic graft copolymers composed of gamma-PGA as the hydrophilic backbone and l-PAE as the hydrophobic segment were successfully synthesized by grafting l-PAE to gamma-PGA using water-soluble carbodiimide (WSC). Due to their amphiphilic properties, the gamma-PGA-graft-l-PAE copolymers were able to form nanoparticles. The size of the gamma-PGA nanoparticles was measured by photon correlation spectroscopy (PCS) and showed a monodispersed size distribution with a mean diameter ranging from 150 to 200 nm. The solvents selected to prepare the gamma-PGA nanoparticles by a precipitation and dialysis method affected the particle size distribution. To evaluate the feasibility of vehicles for these proteins, we prepared protein-loaded gamma-PGA nanoparticles by surface immobilization and encapsulation methods. Ovalbumin (OVA) was used as a model protein and was immobilized onto the gamma-PGA nanoparticles or encapsulated into the inner core of these nanoparticles. Moreover, these OVA-encapsulated gamma-PGA nanoparticles could be preserved by freeze-drying process. The results of cytotoxicity tests showed that the gamma-PGA and gamma-PGA nanoparticles did not cause any relevant cell damage. It is expected that biodegradable gamma-PGA nanoparticles can immobilize proteins, peptides, plasmid DNA and drugs onto their surfaces and/or into the nanoparticles. These nanoparticles are potentially useful in pharmaceutical and biomedical applications.
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PMID:Preparation and characterization of biodegradable nanoparticles based on poly(gamma-glutamic acid) with l-phenylalanine as a protein carrier. 1612 67

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) at 5 microg/ml flocculated bentonite suspension pretreated with polyaluminum chloride (PAC) at 2 microg/ml Al3+-PAC to a transparency of approximately 30% after 30 min and more than 90% after 4 h, while Al3+ concentration in the upper phase of the suspension decreased with incubation time. When pretreated with FeCl3 at 16 microg/ml Fe3+-FeCl3, similar results were obtained. In the case of Escherichia coli suspension, the combination of C-L gamma-PGA and FeCl3 demonstrated a more marked flocculating activity with a satisfactory transparency occurring after 30 min of treatment, accompanied by a decrease in residual Fe3+ concentration. In the above two suspensions pretreated with FeCl3, small visible floats appeared in the early stage of incubation. These floats were found to be due to the direct interaction between FeCl3 and C-L gamma-PGA, indicating the formation of a water-insoluble complex. After allowing the suspension to stand for a long time, elemental analysis and inductively coupled plasma spectroscopy of the precipitates produced suggested that not only the complex was formed due to the interaction between Fe3+ in FeCl3 and COO- in the C-L gamma-PGA molecule, but also Fe2O3 and Fe(OH)3 might be entrapped in this complex. This could be applied to scavenge metal ions including Fe3+ from polluted water.
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PMID:Flocculating activity of cross-linked poly-gamma-glutamic acid against bentonite and Escherichia coli suspension pretreated with FeCl3 and its interaction with Fe3+. 1619 66

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) was prepared with gamma-PGA irradiated with gamma-ray at various kGy values. The physicochemical properties including viscosity and water absorption capacity were compared between C-L gamma-PGA and several typical flocculating agents. The viscosity of C-L gamma-PGA increased with the dose of gamma-irradiation, although the water absorption capacity of C-L gamma-PGA did not, which showed a maximum of 1005.6 ml/g at 20 kGy. Flocculating activity against kaolin suspension was not observed for any of the test compounds when used singly. However, the activity of C-L gamma-PGA markedly increased following the addition of polyaluminum chloride. The activity increased with temperature up to 80 degrees C and remained at 80 degrees C of heat pretreatment for 1 h, but did not at more than 50 degrees C of heat pretreatment for 24 h. The activity was also observed within a pH range of 4.5-10.0. Both the water absorption capacity and flocculating activity of C-L gamma-PGA decreased in parallel with increasing NaCl concentration, suggesting that the flocculating activity of C-L gamma-PGA was associated with its water absorption capacity, rather than viscosity. An investigation of the effects of various cations on the flocculating activity of C-L gamma-PGA showed that only trivalent cations had a synergistic effect. The mechanism of C-L gamma-PGA flocculating activity is discussed based on the results of preliminary experiments.
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PMID:Physicochemical properties of cross-linked poly-gamma-glutamic acid and its flocculating activity against kaolin suspension. 1623 84


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