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

Poly(gamma-glutamic acid) (gamma-PGA), an extracellular polymeric substance (EPS) synthesized by Bacillus species, was explored to study its interaction with the basic brown 1 dye by conducting a systematic batch adsorption study as affected by two critical parameters, temperature and pH. Adsorption isotherms were closely predicted by Temkin equation among the eight isotherm models tested. The rate of adsorption was very rapid attaining equilibrium within 60 min and the kinetics were well described by both modified second-order and pseudo second-order models. Boyd's ion exchange model, which assumes exchanges of ions to be a chemical phenomenon, also fitted the kinetic data precisely. The adsorption rate increased with increasing solution temperature, however, a reversed trend was observed for the adsorption capacity. Changes in enthalpy, entropy and free energy values revealed dye adsorption by gamma-PGA to be an exothermic and spontaneous process involving no structural modification in gamma-PGA, whereas the activation energy of 37.21 kJ/mol indicated dye adsorption to be reaction-controlled. Following a rise in solution pH, the dye adsorption increased and reached a plateau at pH 5, while the maximum release of dye from spent gamma-PGA occurred at pH 1.5, suggesting a possible ion exchange mechanism. Ion exchange adsorption of basic dyes by gamma-PGA was further proved by the presence of two new IR bands at approximately 1600 and 1405.72 cm(-1), representing asymmetric and symmetric stretching vibration of carboxylate anion, for dye-treated gamma-PGA.
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PMID:Effects of temperature and pH on adsorption of basic brown 1 by the bacterial biopolymer poly(gamma-glutamic acid). 1746 83

Preparation of a poly (gamma-glutamic acid)-cisplatin conjugate was introduced and its in vitro antitumor effect was investigated. Poly (gamma-glutamic acids) was obtained by using fermentation methods. The hydrolyzed small molecular weight of poly (gamma-glutamic acids) was prepared by acid hydrolysis. The interaction between poly (gamma-glutamic acids) -cisplatin conjugate (PGA-CDDP) and DNA was investigated by PCR model. MTT assay was used to investigate the in vitro anticancer activity of the conjugate. Apoptosis assay of the conjugate was investigated by FCM assay and the in vivo toxicity was also proceeded. The results showed that the poly (gamma-glutamic acids) -cisplatin conjugate was obtained successfully and its yield is 10% - 12%. It has obvious antitumor effects on human liver tumor BEL7404 cells, human lung tumor H446 cells and human colon tumor RKO cells. At the same time, it also has apoptosis effects on the three kinds of tumor cell lines. The in vivo toxicity of PGA-CDDP was examined in normal mice and the results showed that the in vivo toxicity of this conjugate was significantly lower than that of free CDDP. In conclusion, the poly (gamma-glutamic acids) -cisplatin conjuate could be used as a potential clinic antitumor drug. The poly (gamma-glutamic acids) obtained by fermentation can be used as a valuable drug carrier system.
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PMID:[Preparation and biological activity of poly (gamma-glutamic acid) -cisplatin conjugate]. 1770 97

Poly(gamma-glutamic acid) (gamma-PGA) is a material of polymer. Immobilization of Candida rugosa lipase (Lipase AY-30) by covalent binding on gamma-PGA led to a markedly improved performance of the enzyme. Response surface methodology (RSM) and 3-level-3-factor fractional factorial design were employed to evaluate the effects of immobilization parameters, such as immobilization time (2-6h), immobilization temperature (0-26 degrees C), and enzyme/support ratio (0.1-0.5, w/w). Based on the analysis of ridge max, the optimum immobilization conditions were as follows: immobilization time 2.3h, immobilization temperature 13.3 degrees C, and enzyme/support ratio 0.41 (w/w); the highest lipase activity obtained was 1196 U/mg-protein.
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PMID:Studies of optimum conditions for covalent immobilization of Candida rugosa lipase on poly(gamma-glutamic acid) by RSM. 1770 21

A novel polydimethylsiloxane (PDMS) surface modification method for microchip electrophoresis has been developed to make a stable and sufficient electroosmotic flow (EOF). Poly(l-glutamic acid) (PGA) which had ionizable carboxyl groups at a high pH-range was immobilized on the surface of microchannel fabricated with PDMS. The surface modification involved surface oxidation by plasma, the silanization of 3-aminopropyldimethylethoxysilane (APDMES) and immobilization of PGA via amide bond. The modified channel was extremely stable against consecutive electric power supply over 5h, and its long-term stability was demonstrated by the efficient separation of four amino acid derivatives reproducibly after a week. Additionally, homocysteine (Hcy), important risk factor of cardiovascular disease, osteoporosis and problems in pregnancy, was successfully measured in human serum in modified PDMS channel with the other thio amino acid simultaneously.
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PMID:Steady surface modification of polydimethylsiloxane microchannel and its application in simultaneous analysis of homocysteine and glutathione in human serum. 1776 Nov 87

Poly(gamma-glutamic acid)s (gamma-PGA) modified with phloridzin, which is an inhibitor of the Na(+)/glucose cotransporter (SGLT1), via a omega-amino triethylene glycol linker were synthesized. The potential of gamma-PGA-phloridzin conjugates (PGA-PRZs) obtained as a novel oral anti-diabetic drug was examined by in vitro and in vivo experiments. A PGA-PRZ with a 15% phloridzin content inhibited glucose transport from mucosal to serosal sides of the everted rat's small intestine, and its inhibitory effect was as strong as that of intact phloridzin. When the PGA-PRZ was given orally to rats before glucose administration, the glucose-induced hyperglycemic effect was significantly suppressed. On the other hand, reduction of an increase in the blood glucose concentration was scarcely observed when the PGA-PRZ was substituted with a double amount of intact phloridzin. This difference in the biological activity between PGA-PRZ and intact phloridzin might have resulted from the improved stability of a glucoside bond of phloridzin through the conjugation with gamma-PGA. These results suggest that the gamma-PGA-phloridzin conjugates have potential as oral anti-diabetic drugs.
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PMID:Polymer-phloridzin conjugates as an anti-diabetic drug that inhibits glucose absorption through the Na+/glucose cotransporter (SGLT1) in the small intestine. 1800 67

Escherichia coli contains a four-gene operon, pgaABCD, which encodes the proteins necessary for the synthesis of polymeric N-acetylglucosamine, or PGA. Poly-N-acetyl-glucosamine was first described in Staphylococcus aureus and Staphylococcus epidermidis and was found to have important roles in biofilm formation and immune evasion. PGA also plays a role in biofilm formation in E. coli, but its role in immune evasion has not been thoroughly studied. We previously reported that E. coli PGA cross-reacts with an opsonic-antibody raised against S. aureus PNAG and this is the basis for an ongoing investigation regarding the development of a vaccine against both pathogens. In this paper we investigated pga expression in wild type and csrA or nhaR deletion mutant strains during different growth phases and temperatures, and in response to chemical stimuli using a pga promoter-reporter fusion construct, real-time reverse transcriptase-PCR, immunoblotting, and biofilm assays. Expression of pga and polysaccharide synthesis were induced by glucose, NaCl, and ethanol, but only glucose augmented biofilm formation. The regulatory factor NhaR was required for NaCl-induced pga expression, whereas the effects of glucose and ethanol were independent of CsrA and NhaR.
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PMID:Effect of growth conditions on poly-N-acetylglucosamine expression and biofilm formation in Escherichia coli. 1844 67

Poly(gamma-glutamic acid) (PGA) produced by a strain of Bacillus subtilis was partially hydrolyzed into various oligopeptides so that the dipeptide fraction was isolated by the preparative thin-layer chromatography. HPLC analysis was applied to the detection of each of the four stereoisomers in this fraction using chemically synthesized authentic samples. The fraction consisted of N-gamma- d-glutamyl- d-glutamic acid, N-gamma- l-glutamyl- l-glutamic acid, N-gamma- d-glutamyl- l-glutamic acid, and N-gamma- l-glutamyl- d-glutamic acid at a ratio of 5.9:6.0:1.0:1.0. On the basis of this result, a model was proposed for the microstructure of the bacterial PGA, in which d- and l-glutamic acid repeating units are alternately linked in a single chain of the molecule.
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PMID:Microstructure of poly(gamma-glutamic acid) produced by Bacillus subtilis consisting of clusters of D- and L-glutamic acid repeating units. 1848 8

Poly-gamma-glutamic acid (gamma-PGA) is a kind of water-soluble and biodegradable polymer made from D- and L-glutamic acid units, which are linked by amide bonds formed between alpha-amino and gamma-carboxylic acid groups. As a potential targeted biopolymer that can be refined from biomass directly, gamma-PGA has been increasingly applied to food, cosmetic, and pharmaceutical industries. In this work, a suitable nitrogen source was screened out for the high and cost-effective production of gamma-PGA in Bacillus subtilis ZJU-7. The effects of inoculation time and initial glucose concentration on the gamma-PGA production were investigated systematically in both shake flasks and a bench-top 15-l fermentor. Under the optimized culture conditions, a high gamma-PGA productivity (46.4 g/l) was obtained after 48 h cultivation at 37 degrees C. Finally, the large-scale fermentation of gamma-PGA production was successfully scaled up to a 100-l fermentor, with the highest gamma-PGA productivity for over 54.0 g/l.
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PMID:Effects of cultivation conditions on the production of gamma-PGA with Bacillus subtilis ZJU-7. 1866 74

Poly-gamma-glutamic acid (gamma-PGA) is an extracellular polymer produced by various strains of Bacillus. Iotat was first described as the component of the capsule in Bacillus anthracis, where it plays a relevant role in virulence. gamma-PGA is also a distinctive component of 'natto', a traditional Japanese food consisting of soybean fermented by Bacillus subtilis (natto). Domesticated B. subtilis strains do not synthesize gamma-PGA although they possess the functional biosynthetic pgs operon. In the present work we explore the correlation between the genetic determinants, swrAA and degU, which allow a derivative of the domestic strain JH642 to display a mucoid colony morphology on LB agar plates due to the production of gamma-PGA. Full activation of the pgs operon requires the co-presence of SwrAA and the phosphorylated form of DegU (DegU approximately P). The presence of either DegU approximately P or SwrAA alone has only marginal effects on pgs operon transcription and gamma-PGA production. Although SwrAA was identified as necessary for swarming and full swimming motility together with DegU, we show that motility is not involved in gamma-PGA production. Activation of gamma-PGA synthesis is therefore a motility-independent phenotype in which SwrAA and DegU approximately P display a cooperative effect.
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PMID:SwrAA activates poly-gamma-glutamate synthesis in addition to swarming in Bacillus subtilis. 1938 63

Poly(trimethylene carbonate)-b-poly(L-glutamic acid) (PTMC-b-PGA) diblock copolymers have been synthesized by ring-opening polymerization (ROP) of gamma-benzyl-L-glutamate N-carboxyanhydride (BLG) initiated by amino functionalized PTMC and subsequent hydrogenation. Self-assembly in water gave well-defined vesicles which have been studied combining light and neutron scattering techniques with electron microscopy imaging. The size and dispersity of vesicles have been tuned by varying preparation conditions, direct dissolution, or nanoprecipitation. In addition, PGA conformation could be reversibly manipulated as a function of environmental changes such as pH and ionic strength. Vesicles showed high tolerance and stability toward nonionic surfactant and pH due to a thick membrane and were revealed to be nonpermeable to water. Nevertheless, they can be rapidly degraded by enzymatic hydrolysis of the polycarbonate block. The ability to tune their size through the formation process, their stimuli responsiveness, their high stability, and their biodegradability make them suitable for biomedical applications.
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PMID:Biocompatible and biodegradable poly(trimethylene carbonate)-b-poly(L-glutamic acid) polymersomes: size control and stability. 1979 94


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