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Sample records for high glycolate oxidase

  1. High glycolate oxidase activity is required for survival of maize in normal air.

    PubMed

    Zelitch, Israel; Schultes, Neil P; Peterson, Richard B; Brown, Patrick; Brutnell, Thomas P

    2009-01-01

    A mutant in the maize (Zea mays) Glycolate Oxidase1 (GO1) gene was characterized to investigate the role of photorespiration in C4 photosynthesis. An Activator-induced allele of GO1 conditioned a seedling lethal phenotype when homozygous and had 5% to 10% of wild-type GO activity. Growth of seedlings in high CO2 (1%-5%) was sufficient to rescue the mutant phenotype. Upon transfer to normal air, the go1 mutant became necrotic within 7 d and plants died within 15 d. Providing [1-14C]glycolate to leaf tissue of go1 mutants in darkness confirmed that the substrate is inefficiently converted to 14CO2, but both wild-type and GO-deficient mutant seedlings metabolized [1-14C]glycine similarly to produce [14C]serine and 14CO2 in a 1:1 ratio, suggesting that the photorespiratory pathway is otherwise normal in the mutant. The net CO2 assimilation rate in wild-type leaves was only slightly inhibited in 50% O2 in high light but decreased rapidly and linearly with time in leaves with low GO. When go1 mutants were shifted from high CO2 to air in light, they accumulated glycolate linearly for 6 h to levels 7-fold higher than wild type and 11-fold higher after 25 h. These studies show that C4 photosynthesis in maize is dependent on photorespiration throughout seedling development and support the view that the carbon oxidation pathway evolved to prevent accumulation of toxic glycolate. PMID:18805949

  2. Overexpression of Glycolate Oxidase Confers Improved Photosynthesis under High Light and High Temperature in Rice.

    PubMed

    Cui, Li-Li; Lu, Yu-Sheng; Li, Yong; Yang, Chengwei; Peng, Xin-Xiang

    2016-01-01

    While glycolate oxidase (GLO) is well known as a key enzyme for the photorespiratory metabolism in plants, its physiological function and mechanism remains to be further clarified. Our previous studies have shown that suppression of GLO in rice leads to stunted growth and inhibited photosynthesis (Pn) which is positively and linearly correlated with decreased GLO activities. It is, therefore, of interest to further understand whether Pn can be improved when GLO is up-regulated? In this study, four independent overexpression rice lines, with gradient increases in GLO activity, were generated and functionally analyzed. Phenotypic observations showed that the growth could be improved when GLO activities were increased by 60 or 100%, whereas reduced growth was noticed when the activity was further increased by 150 or 210%. As compared with WT plants, all the overexpression plants exhibited significantly improved Pn under conditions of high light and high temperature, but not under normal conditions. In addition, the overexpression plants were more resistant to the MV-induced photooxidative stress. It was further demonstrated that the antioxidant enzymes, and the antioxidant metabolite glutathione was not significantly altered in the overexpression plants. In contrast, H2O2 and salicylic acid (SA) were correspondingly induced upon the GLO overexpression. Taken together, the results suggest that GLO may play an important role for plants to cope with high light and high temperature, and that H2O2 and SA may serve as signaling molecules to trigger stress defense responses but antioxidant reactions appear not to be involved in the defense. PMID:27540387

  3. Overexpression of Glycolate Oxidase Confers Improved Photosynthesis under High Light and High Temperature in Rice

    PubMed Central

    Cui, Li-Li; Lu, Yu-sheng; Li, Yong; Yang, Chengwei; Peng, Xin-Xiang

    2016-01-01

    While glycolate oxidase (GLO) is well known as a key enzyme for the photorespiratory metabolism in plants, its physiological function and mechanism remains to be further clarified. Our previous studies have shown that suppression of GLO in rice leads to stunted growth and inhibited photosynthesis (Pn) which is positively and linearly correlated with decreased GLO activities. It is, therefore, of interest to further understand whether Pn can be improved when GLO is up-regulated? In this study, four independent overexpression rice lines, with gradient increases in GLO activity, were generated and functionally analyzed. Phenotypic observations showed that the growth could be improved when GLO activities were increased by 60 or 100%, whereas reduced growth was noticed when the activity was further increased by 150 or 210%. As compared with WT plants, all the overexpression plants exhibited significantly improved Pn under conditions of high light and high temperature, but not under normal conditions. In addition, the overexpression plants were more resistant to the MV-induced photooxidative stress. It was further demonstrated that the antioxidant enzymes, and the antioxidant metabolite glutathione was not significantly altered in the overexpression plants. In contrast, H2O2 and salicylic acid (SA) were correspondingly induced upon the GLO overexpression. Taken together, the results suggest that GLO may play an important role for plants to cope with high light and high temperature, and that H2O2 and SA may serve as signaling molecules to trigger stress defense responses but antioxidant reactions appear not to be involved in the defense. PMID:27540387

  4. The Occurrence of Glycolate Dehydrogenase and Glycolate Oxidase in Green Plants

    PubMed Central

    Frederick, Sue Ellen; Gruber, Peter J.; Tolbert, N. E.

    1973-01-01

    Homogenates of various lower land plants, aquatic angiosperms, and green algae were assayed for glycolate oxidase, a peroxisomal enzyme present in green leaves of higher plants, and for glycolate dehydrogenase, a functionally analogous enzyme characteristic of certain green algae. Green tissues of all lower land plants examined (including mosses, liverworts, ferns, and fern allies), as well as three freshwater aquatic angiosperms, contained an enzyme resembling glycolate oxidase, in that it oxidized l- but not d-lactate in addition to glycolate, and was insensitive to 2 mm cyanide. Many of the green algae (including Chlorella vulgaris, previously claimed to have glycolate oxidase) contained an enzyme resembling glycolate dehydrogenase, in that it oxidized d- but not l-lactate, and was inhibited by 2 mm cyanide. Other green algae had activity characteristic of glycolate oxidase and, accordingly, showed a substantial glycolate-dependent O2 uptake. It is pointed out that this distribution pattern of glycolate oxidase and glycolate dehydrogenase among the green plants may have phylogenetic significance. Activities of catalase, a marker enzyme for peroxisomes, were also determined and were generally lower in the algae than in the land plants or aquatic angiosperms. Among the algae, however, there were no consistent correlations between levels of catalase and the type of enzyme which oxidized glycolate. PMID:16658555

  5. Lack of GLYCOLATE OXIDASE1, but Not GLYCOLATE OXIDASE2, Attenuates the Photorespiratory Phenotype of CATALASE2-Deficient Arabidopsis.

    PubMed

    Kerchev, Pavel; Waszczak, Cezary; Lewandowska, Aleksandra; Willems, Patrick; Shapiguzov, Alexey; Li, Zhen; Alseekh, Saleh; Mühlenbock, Per; Hoeberichts, Frank A; Huang, Jingjing; Van Der Kelen, Katrien; Kangasjärvi, Jaakko; Fernie, Alisdair R; De Smet, Riet; Van de Peer, Yves; Messens, Joris; Van Breusegem, Frank

    2016-07-01

    The genes coding for the core metabolic enzymes of the photorespiratory pathway that allows plants with C3-type photosynthesis to survive in an oxygen-rich atmosphere, have been largely discovered in genetic screens aimed to isolate mutants that are unviable under ambient air. As an exception, glycolate oxidase (GOX) mutants with a photorespiratory phenotype have not been described yet in C3 species. Using Arabidopsis (Arabidopsis thaliana) mutants lacking the peroxisomal CATALASE2 (cat2-2) that display stunted growth and cell death lesions under ambient air, we isolated a second-site loss-of-function mutation in GLYCOLATE OXIDASE1 (GOX1) that attenuated the photorespiratory phenotype of cat2-2 Interestingly, knocking out the nearly identical GOX2 in the cat2-2 background did not affect the photorespiratory phenotype, indicating that GOX1 and GOX2 play distinct metabolic roles. We further investigated their individual functions in single gox1-1 and gox2-1 mutants and revealed that their phenotypes can be modulated by environmental conditions that increase the metabolic flux through the photorespiratory pathway. High light negatively affected the photosynthetic performance and growth of both gox1-1 and gox2-1 mutants, but the negative consequences of severe photorespiration were more pronounced in the absence of GOX1, which was accompanied with lesser ability to process glycolate. Taken together, our results point toward divergent functions of the two photorespiratory GOX isoforms in Arabidopsis and contribute to a better understanding of the photorespiratory pathway. PMID:27225899

  6. Decreased glycolate oxidase activity leads to altered carbon allocation and leaf senescence after a transfer from high CO2 to ambient air in Arabidopsis thaliana.

    PubMed

    Dellero, Younès; Jossier, Mathieu; Glab, Nathalie; Oury, Céline; Tcherkez, Guillaume; Hodges, Michael

    2016-05-01

    Metabolic and physiological analyses of Arabidopsis thaliana glycolate oxidase (GOX) mutant leaves were performed to understand the development of the photorespiratory phenotype after transfer from high CO2 to air. We show that two Arabidopsis genes, GOX1 and GOX2, share a redundant photorespiratory role. Air-grown single gox1 and gox2 mutants grew normally and no significant differences in leaf metabolic levels and photosynthetic activities were found when compared with wild-type plants. To study the impact of a highly reduced GOX activity on plant metabolism, both GOX1 and GOX2 expression was knocked-down using an artificial miRNA strategy. Air-grown amiRgox1/2 plants with a residual 5% GOX activity exhibited a severe growth phenotype. When high-CO2-grown adult plants were transferred to air, the photosynthetic activity of amiRgox1/2 was rapidly reduced to 50% of control levels, and a high non-photochemical chlorophyll fluorescence quenching was maintained. (13)C-labeling revealed that daily assimilated carbon accumulated in glycolate, leading to reduced carbon allocation to sugars, organic acids, and amino acids. Such changes were not always mirrored in leaf total metabolite levels, since many soluble amino acids increased after transfer, while total soluble protein, RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), and chlorophyll amounts decreased in amiRgox1/2 plants. The senescence marker, SAG12, was induced only in amiRgox1/2 rosettes after transfer to air. The expression of maize photorespiratory GOX in amiRgox1/2 abolished all observed phenotypes. The results indicate that the inhibition of the photorespiratory cycle negatively impacts photosynthesis, alters carbon allocation, and leads to early senescence in old rosette leaves. PMID:26896850

  7. Molecular cloning of mouse glycolate oxidase. High evolutionary conservation and presence of an iron-responsive element-like sequence in the mRNA.

    PubMed

    Kohler, S A; Menotti, E; Kühn, L C

    1999-01-22

    Iron regulatory proteins (IRPs) control the synthesis of several proteins in iron metabolism by binding to iron-responsive elements (IREs), a hairpin structure in the untranslated region (UTR) of corresponding mRNAs. Binding of IRPs to IREs in the 5' UTR inhibits translation of ferritin heavy and light chain, erythroid aminolevulinic acid synthase, mitochondrial aconitase, and Drosophila succinate dehydrogenase b, whereas IRP binding to IREs in the 3' UTR of transferrin receptor mRNA prolongs mRNA half-life. To identify new targets of IRPs, we devised a method to enrich IRE-containing mRNAs by using recombinant IRP-1 as an affinity matrix. A cDNA library established from enriched mRNA was screened by an RNA-protein band shift assay. This revealed a novel IRE-like sequence in the 3' UTR of a liver-specific mouse mRNA. The newly identified cDNA codes for a protein with high homology to plant glycolate oxidase (GOX). Recombinant protein expressed in bacteria displayed enzymatic GOX activity. Therefore, this cDNA represents the first vertebrate GOX homologue. The IRE-like sequence in mouse GOX exhibited strong binding to IRPs at room temperature. However, it differs from functional IREs by a mismatch in the middle of its upper stem and did not confer iron-dependent regulation in cells. PMID:9891009

  8. Cyanobacterial lactate oxidases serve as essential partners in N2 fixation and evolved into photorespiratory glycolate oxidases in plants.

    PubMed

    Hackenberg, Claudia; Kern, Ramona; Hüge, Jan; Stal, Lucas J; Tsuji, Yoshinori; Kopka, Joachim; Shiraiwa, Yoshihiro; Bauwe, Hermann; Hagemann, Martin

    2011-08-01

    Glycolate oxidase (GOX) is an essential enzyme involved in photorespiratory metabolism in plants. In cyanobacteria and green algae, the corresponding reaction is catalyzed by glycolate dehydrogenases (GlcD). The genomes of N(2)-fixing cyanobacteria, such as Nostoc PCC 7120 and green algae, appear to harbor genes for both GlcD and GOX proteins. The GOX-like proteins from Nostoc (No-LOX) and from Chlamydomonas reinhardtii showed high L-lactate oxidase (LOX) and low GOX activities, whereas glycolate was the preferred substrate of the phylogenetically related At-GOX2 from Arabidopsis thaliana. Changing the active site of No-LOX to that of At-GOX2 by site-specific mutagenesis reversed the LOX/GOX activity ratio of No-LOX. Despite its low GOX activity, No-LOX overexpression decreased the accumulation of toxic glycolate in a cyanobacterial photorespiratory mutant and restored its ability to grow in air. A LOX-deficient Nostoc mutant grew normally in nitrate-containing medium but died under N(2)-fixing conditions. Cultivation under low oxygen rescued this lethal phenotype, indicating that N(2) fixation was more sensitive to O(2) in the Δlox Nostoc mutant than in the wild type. We propose that LOX primarily serves as an O(2)-scavenging enzyme to protect nitrogenase in extant N(2)-fixing cyanobacteria, whereas in plants it has evolved into GOX, responsible for glycolate oxidation during photorespiration. PMID:21828292

  9. Lack of GLYCOLATE OXIDASE1, but Not GLYCOLATE OXIDASE2, Attenuates the Photorespiratory Phenotype of CATALASE2-Deficient Arabidopsis1[OPEN

    PubMed Central

    Waszczak, Cezary; Lewandowska, Aleksandra; Shapiguzov, Alexey; Alseekh, Saleh; Hoeberichts, Frank A.; Huang, Jingjing; Van Der Kelen, Katrien; Fernie, Alisdair R.; De Smet, Riet; Van de Peer, Yves; Messens, Joris

    2016-01-01

    The genes coding for the core metabolic enzymes of the photorespiratory pathway that allows plants with C3-type photosynthesis to survive in an oxygen-rich atmosphere, have been largely discovered in genetic screens aimed to isolate mutants that are unviable under ambient air. As an exception, glycolate oxidase (GOX) mutants with a photorespiratory phenotype have not been described yet in C3 species. Using Arabidopsis (Arabidopsis thaliana) mutants lacking the peroxisomal CATALASE2 (cat2-2) that display stunted growth and cell death lesions under ambient air, we isolated a second-site loss-of-function mutation in GLYCOLATE OXIDASE1 (GOX1) that attenuated the photorespiratory phenotype of cat2-2. Interestingly, knocking out the nearly identical GOX2 in the cat2-2 background did not affect the photorespiratory phenotype, indicating that GOX1 and GOX2 play distinct metabolic roles. We further investigated their individual functions in single gox1-1 and gox2-1 mutants and revealed that their phenotypes can be modulated by environmental conditions that increase the metabolic flux through the photorespiratory pathway. High light negatively affected the photosynthetic performance and growth of both gox1-1 and gox2-1 mutants, but the negative consequences of severe photorespiration were more pronounced in the absence of GOX1, which was accompanied with lesser ability to process glycolate. Taken together, our results point toward divergent functions of the two photorespiratory GOX isoforms in Arabidopsis and contribute to a better understanding of the photorespiratory pathway. PMID:27225899

  10. Experimental Evidence for a Hydride Transfer Mechanism in Plant Glycolate Oxidase Catalysis*

    PubMed Central

    Dellero, Younès; Mauve, Caroline; Boex-Fontvieille, Edouard; Flesch, Valérie; Jossier, Mathieu; Tcherkez, Guillaume; Hodges, Michael

    2015-01-01

    In plants, glycolate oxidase is involved in the photorespiratory cycle, one of the major fluxes at the global scale. To clarify both the nature of the mechanism and possible differences in glycolate oxidase enzyme chemistry from C3 and C4 plant species, we analyzed kinetic parameters of purified recombinant C3 (Arabidopsis thaliana) and C4 (Zea mays) plant enzymes and compared isotope effects using natural and deuterated glycolate in either natural or deuterated solvent. The 12C/13C isotope effect was also investigated for each plant glycolate oxidase protein by measuring the 13C natural abundance in glycolate using natural or deuterated glycolate as a substrate. Our results suggest that several elemental steps were associated with an hydrogen/deuterium isotope effect and that glycolate α-deprotonation itself was only partially rate-limiting. Calculations of commitment factors from observed kinetic isotope effect values support a hydride transfer mechanism. No significant differences were seen between C3 and C4 enzymes. PMID:25416784

  11. Photorespiratory glycolate oxidase is essential for the survival of the red alga Cyanidioschyzon merolae under ambient CO2 conditions

    PubMed Central

    Rademacher, Nadine; Kern, Ramona; Fujiwara, Takayuki; Mettler-Altmann, Tabea; Miyagishima, Shin-ya; Hagemann, Martin; Eisenhut, Marion; Weber, Andreas P.M.

    2016-01-01

    Photorespiration is essential for all organisms performing oxygenic photosynthesis. The evolution of photorespiratory metabolism began among cyanobacteria and led to a highly compartmented pathway in plants. A molecular understanding of photorespiration in eukaryotic algae, such as glaucophytes, rhodophytes, and chlorophytes, is essential to unravel the evolution of this pathway. However, mechanistic detail of the photorespiratory pathway in red algae is scarce. The unicellular red alga Cyanidioschyzon merolae represents a model for the red lineage. Its genome is fully sequenced, and tools for targeted gene engineering are available. To study the function and importance of photorespiration in red algae, we chose glycolate oxidase (GOX) as the target. GOX catalyses the conversion of glycolate into glyoxylate, while hydrogen peroxide is generated as a side-product. The function of the candidate GOX from C. merolae was verified by the fact that recombinant GOX preferred glycolate over L-lactate as a substrate. Yellow fluorescent protein-GOX fusion proteins showed that GOX is targeted to peroxisomes in C. merolae. The GOX knockout mutant lines showed a high-carbon-requiring phenotype with decreased growth and reduced photosynthetic activity compared to the wild type under ambient air conditions. Metabolite analyses revealed glycolate and glycine accumulation in the mutant cells after a shift from high CO2 conditions to ambient air. In summary, or results demonstrate that photorespiratory metabolism is essential for red algae. The use of a peroxisomal GOX points to a high photorespiratory flux as an ancestral feature of all photosynthetic eukaryotes. PMID:26994474

  12. Photorespiratory glycolate oxidase is essential for the survival of the red alga Cyanidioschyzon merolae under ambient CO2 conditions.

    PubMed

    Rademacher, Nadine; Kern, Ramona; Fujiwara, Takayuki; Mettler-Altmann, Tabea; Miyagishima, Shin-Ya; Hagemann, Martin; Eisenhut, Marion; Weber, Andreas P M

    2016-05-01

    Photorespiration is essential for all organisms performing oxygenic photosynthesis. The evolution of photorespiratory metabolism began among cyanobacteria and led to a highly compartmented pathway in plants. A molecular understanding of photorespiration in eukaryotic algae, such as glaucophytes, rhodophytes, and chlorophytes, is essential to unravel the evolution of this pathway. However, mechanistic detail of the photorespiratory pathway in red algae is scarce. The unicellular red alga Cyanidioschyzon merolae represents a model for the red lineage. Its genome is fully sequenced, and tools for targeted gene engineering are available. To study the function and importance of photorespiration in red algae, we chose glycolate oxidase (GOX) as the target. GOX catalyses the conversion of glycolate into glyoxylate, while hydrogen peroxide is generated as a side-product. The function of the candidate GOX from C. merolae was verified by the fact that recombinant GOX preferred glycolate over L-lactate as a substrate. Yellow fluorescent protein-GOX fusion proteins showed that GOX is targeted to peroxisomes in C. merolae The GOX knockout mutant lines showed a high-carbon-requiring phenotype with decreased growth and reduced photosynthetic activity compared to the wild type under ambient air conditions. Metabolite analyses revealed glycolate and glycine accumulation in the mutant cells after a shift from high CO2 conditions to ambient air. In summary, or results demonstrate that photorespiratory metabolism is essential for red algae. The use of a peroxisomal GOX points to a high photorespiratory flux as an ancestral feature of all photosynthetic eukaryotes. PMID:26994474

  13. Effect of exogenous methanol on glycolate oxidase and photorespiratory intermediates in cotton

    PubMed Central

    Bai, Yan-Ru; Yang, Ping; Su, Yuan-Yuan; He, Zong-Ling; Ti, Xiao-Nan

    2014-01-01

    Application of methanol (MeOH) inhibits photorespiration and enhances growth and yield in C3 plants. However, the underlying cellular and molecular mechanisms are not clear. In this study, we investigated the effects of foliar application of MeOH (30%, v/v) on glycolate oxidase (GO) activity and photorespiratory intermediates in cotton leaves in a field experiment. MeOH treatment significantly inhibited GO activity (by 30% compared with the controls). We also found that endogenous glyoxylate, a photorespiratory intermediate, increased and glycine decreased significantly in MeOH-treated plants. Serine increased significantly in MeOH-treated plants. These results thus demonstrated that exogenous MeOH can modulate GO activity and the production of photorespiratory intermediates, and sheds new lights on our current understanding of how exogenous MeOH inhibits photorespiration and enhances the growth and yield of C3 plants such as cotton. PMID:25053644

  14. Active Site and Loop 4 Movements with Human Glycolate Oxidase: Implications for Substrate Specificity and Drug Design

    SciTech Connect

    Murray,M.; Holmes, R.; Lowther, W.

    2008-01-01

    Human glycolate oxidase (GO) catalyzes the FMN-dependent oxidation of glycolate to glyoxylate and glyoxylate to oxalate, a key metabolite in kidney stone formation. We report herein the structures of recombinant GO complexed with sulfate, glyoxylate, and an inhibitor, 4-carboxy-5-dodecylsulfanyl-1, 2,3-triazole (CDST), determined by X-ray crystallography. In contrast to most {alpha}-hydroxy acid oxidases including spinach glycolate oxidase, a loop region, known as loop 4, is completely visible when the GO active site contains a small ligand. The lack of electron density for this loop in the GO-CDST complex, which mimics a large substrate, suggests that a disordered to ordered transition may occur with the binding of substrates. The conformational flexibility of Trp110 appears to be responsible for enabling GO to react with a-hydroxy acids of various chain lengths. Moreover, the movement of Trp110 disrupts a hydrogen-bonding network between Trp110, Leu191, Tyr134, and Tyr208. This loss of interactions is the first indication that active site movements are directly linked to changes in the conformation of loop 4. The kinetic parameters for the oxidation of glycolate, glyoxylate, and 2-hydroxy octanoate indicate that the oxidation of glycolate to glyoxylate is the primary reaction catalyzed by GO, while the oxidation of glyoxylate to oxalate is most likely not relevant under normal conditions. However, drugs that exploit the unique structural features of GO may ultimately prove to be useful for decreasing glycolate and glyoxylate levels in primary hyperoxaluria type 1 patients who have the inability to convert peroxisomal glyoxylate to glycine.

  15. Inhibition of Glycolate Oxidase With Dicer-substrate siRNA Reduces Calcium Oxalate Deposition in a Mouse Model of Primary Hyperoxaluria Type 1.

    PubMed

    Dutta, Chaitali; Avitahl-Curtis, Nicole; Pursell, Natalie; Larsson Cohen, Marita; Holmes, Benjamin; Diwanji, Rohan; Zhou, Wei; Apponi, Luciano; Koser, Martin; Ying, Bo; Chen, Dongyu; Shui, Xue; Saxena, Utsav; Cyr, Wendy A; Shah, Anee; Nazef, Naim; Wang, Weimin; Abrams, Marc; Dudek, Henryk; Salido, Eduardo; Brown, Bob D; Lai, Chengjung

    2016-04-01

    Primary hyperoxaluria type 1 (PH1) is an autosomal recessive, metabolic disorder caused by mutations of alanine-glyoxylate aminotransferase (AGT), a key hepatic enzyme in the detoxification of glyoxylate arising from multiple normal metabolic pathways to glycine. Accumulation of glyoxylate, a precursor of oxalate, leads to the overproduction of oxalate in the liver, which accumulates to high levels in kidneys and urine. Crystalization of calcium oxalate (CaOx) in the kidney ultimately results in renal failure. Currently, the only treatment effective in reduction of oxalate production in patients who do not respond to high-dose vitamin B6 therapy is a combined liver/kidney transplant. We explored an alternative approach to prevent glyoxylate production using Dicer-substrate small interfering RNAs (DsiRNAs) targeting hydroxyacid oxidase 1 (HAO1) mRNA which encodes glycolate oxidase (GO), to reduce the hepatic conversion of glycolate to glyoxylate. This approach efficiently reduces GO mRNA and protein in the livers of mice and nonhuman primates. Reduction of hepatic GO leads to normalization of urine oxalate levels and reduces CaOx deposition in a preclinical mouse model of PH1. Our results support the use of DsiRNA to reduce liver GO levels as a potential therapeutic approach to treat PH1. PMID:26758691

  16. Inhibition of Glycolate Oxidase With Dicer-substrate siRNA Reduces Calcium Oxalate Deposition in a Mouse Model of Primary Hyperoxaluria Type 1

    PubMed Central

    Dutta, Chaitali; Avitahl-Curtis, Nicole; Pursell, Natalie; Larsson Cohen, Marita; Holmes, Benjamin; Diwanji, Rohan; Zhou, Wei; Apponi, Luciano; Koser, Martin; Ying, Bo; Chen, Dongyu; Shui, Xue; Saxena, Utsav; Cyr, Wendy A; Shah, Anee; Nazef, Naim; Wang, Weimin; Abrams, Marc; Dudek, Henryk; Salido, Eduardo; Brown, Bob D; Lai, Chengjung

    2016-01-01

    Primary hyperoxaluria type 1 (PH1) is an autosomal recessive, metabolic disorder caused by mutations of alanine-glyoxylate aminotransferase (AGT), a key hepatic enzyme in the detoxification of glyoxylate arising from multiple normal metabolic pathways to glycine. Accumulation of glyoxylate, a precursor of oxalate, leads to the overproduction of oxalate in the liver, which accumulates to high levels in kidneys and urine. Crystalization of calcium oxalate (CaOx) in the kidney ultimately results in renal failure. Currently, the only treatment effective in reduction of oxalate production in patients who do not respond to high-dose vitamin B6 therapy is a combined liver/kidney transplant. We explored an alternative approach to prevent glyoxylate production using Dicer-substrate small interfering RNAs (DsiRNAs) targeting hydroxyacid oxidase 1 (HAO1) mRNA which encodes glycolate oxidase (GO), to reduce the hepatic conversion of glycolate to glyoxylate. This approach efficiently reduces GO mRNA and protein in the livers of mice and nonhuman primates. Reduction of hepatic GO leads to normalization of urine oxalate levels and reduces CaOx deposition in a preclinical mouse model of PH1. Our results support the use of DsiRNA to reduce liver GO levels as a potential therapeutic approach to treat PH1. PMID:26758691

  17. Plant and animal glycolate oxidases have a common eukaryotic ancestor and convergently duplicated to evolve long-chain 2-hydroxy acid oxidases.

    PubMed

    Esser, Christian; Kuhn, Anke; Groth, Georg; Lercher, Martin J; Maurino, Veronica G

    2014-05-01

    Glycolate oxidase (GOX) is a crucial enzyme of plant photorespiration. The encoding gene is thought to have originated from endosymbiotic gene transfer between the eukaryotic host and the cyanobacterial endosymbiont at the base of plantae. However, animals also possess GOX activities. Plant and animal GOX belong to the gene family of (L)-2-hydroxyacid-oxidases ((L)-2-HAOX). We find that all (L)-2-HAOX proteins in animals and archaeplastida go back to one ancestral eukaryotic sequence; the sole exceptions are green algae of the chlorophyta lineage. Chlorophyta replaced the ancestral eukaryotic (L)-2-HAOX with a bacterial ortholog, a lactate oxidase that may have been obtained through the primary endosymbiosis at the base of plantae; independent losses of this gene may explain its absence in other algal lineages (glaucophyta, rhodophyta, and charophyta). We also show that in addition to GOX, plants possess (L)-2-HAOX proteins with different specificities for medium- and long-chain hydroxyacids (lHAOX), likely involved in fatty acid and protein catabolism. Vertebrates possess lHAOX proteins acting on similar substrates as plant lHAOX; however, the existence of GOX and lHAOX subfamilies in both plants and animals is not due to shared ancestry but is the result of convergent evolution in the two most complex eukaryotic lineages. On the basis of targeting sequences and predicted substrate specificities, we conclude that the biological role of plantae (L)-2-HAOX in photorespiration evolved by co-opting an existing peroxisomal protein. PMID:24408912

  18. Glycolate Oxidase Is a Safe and Efficient Target for Substrate Reduction Therapy in a Mouse Model of Primary Hyperoxaluria Type I.

    PubMed

    Martin-Higueras, Cristina; Luis-Lima, Sergio; Salido, Eduardo

    2016-04-01

    Primary hyperoxaluria type 1 (PH1) is caused by deficient alanine-glyoxylate aminotransferase, the human peroxisomal enzyme that detoxifies glyoxylate. Glycolate is one of the best-known substrates leading to glyoxylate production, via peroxisomal glycolate oxidase (GO). Using genetically modified mice, we herein report GO as a safe and efficient target for substrate reduction therapy (SRT) in PH1. We first generated a GO-deficient mouse (Hao1(-/-)) that presented high urine glycolate levels but no additional phenotype. Next, we produced double KO mice (Agxt1(-/-) Hao1(-/-)) that showed low levels of oxalate excretion compared with hyperoxaluric mice model (Agxt1(-/-)). Previous studies have identified some GO inhibitors, such as 4-carboxy-5-[(4-chlorophenyl)sulfanyl]-1,2,3-thiadiazole (CCPST). We herein report that CCPST inhibits GO in Agxt1(-/-) hepatocytes and significantly reduces their oxalate production, starting at 25 µM. We also tested the ability of orally administered CCPST to reduce oxalate excretion in Agxt1(-/-) mice, showing that 30-50% reduction in urine oxalate can be achieved. In summary, we present proof-of-concept evidence for SRT in PH1. These encouraging results should be followed by a medicinal chemistry programme that might yield more potent GO inhibitors and eventually could result in a pharmacological treatment for this rare and severe inborn error of metabolism. PMID:26689264

  19. Identification and Characterization of Glycolate Oxidase and Related Enzymes from the Endocyanotic Alga Cyanophora paradoxa and from Pea Leaves 1

    PubMed Central

    Betsche, Thomas; Schaller, Dietmar; Melkonian, Michael

    1992-01-01

    Glycolate oxidase (GO) has been identified in the endocyanom Cyanophora paradoxa which has peroxisome-like organelles and cyanelles instead of chloroplasts. The enzyme used or formed equimolar amounts of O2 or H2O2 and glyoxylate, respectively. Aerobically, the enzyme did not reduce the artificial electron acceptor dichlorophenol indophenol. However, after an inhibitor of glycolate dehydrogenase, KCN (2 millimolar), was added to the assay medium, considerable aerobic glycolate:dichlorophenol indophenol reductase activity was detectable. The leaf GO inhibitor 2-hydroxybutynoate (30 micromolar), which binds irreversibly to the flavin moiety of the active site of leaf GO, inhibited Cyanophora GO and pea (Pisum sativum L.) GO to the same extent. This suggests that the active sites of both enzymes are similar. Cyanophora GO and pea GO cannot oxidize d-lactate. In contrast to GO from pea or other organisms, the affinity of Cyanophora GO for l-lactate is very low (Km 25 millimolar). Another important difference is that Cyanophora GO produced sigmoidal kinetics with O2 as varied substrate, whereas pea GO produced normal Michaelis-Menten kinetics. It is concluded that there is considerable inhomogeneity among the glycolate-oxidizing enzymes from Cyanophora, pea, and other organisms. The specific catalase activity in Cyanophora was only one-tenth of that in leaves. NADH-and NADPH-dependent hydroxypyruvate reductase (HPR) and glyoxylate reductase activities were detected in Cyanophora. NADH-HPR was markedly inhibited by hydroxypyruvate above 0.5 millimolar. Variable substrate inhibition was observed with glyoxylate in homogenates from different algal cultures. It is proposed that Cyanophora has multiple forms of HPR and glyoxylate reductase, but no enzyme clearly resembling leaf peroxisomal HPR was identified in these homogenates. Moreover, no serine:glyoxylate aminotransferase activity was detected. These results collectively indicate the possibility that the glycolate

  20. Association-Dissociation of Glycolate Oxidase with Catalase in Rice: A Potential Switch to Modulate Intracellular H2O2 Levels.

    PubMed

    Zhang, Zhisheng; Xu, Yuanyuan; Xie, Zongwang; Li, Xiangyang; He, Zheng-Hui; Peng, Xin-Xiang

    2016-05-01

    Rapid and dynamic change in hydrogen peroxide (H2O2) levels can serve as an important signal to regulate various biological processes in plants. The change is realized by tilting the balance between its production and scavenging rates, in which membrane-associated NADPH oxidases are known to play a crucial role. Functioning independently from NADPH oxidases, glycolate oxidase (GLO) was recently demonstrated as an alternative source for H2O2 production during both gene-for-gene and non-host resistance in plants. In this study, we show that GLO physically interacts with catalase (CAT) in rice leaves, and that the interaction can be deregulated by salicylic acid (SA). Furthermore, the GLO-mediated H2O2 accumulation is synergistically enhanced by SA. Based on the well-known mechanism of substrate channeling in enzyme complexes, SA-induced H2O2 accumulation likely results from SA-induced GLO-CAT dissociation. In the GLO-CAT complex, GLO-mediated H2O2 production during photorespiration is very high, whereas the affinity of CAT for H2O2 (measured Km ≈ 43 mM) is extraordinarily low. This unique combination can further potentiate the increase in H2O2 when GLO is dissociated from CAT. Taken together, we propose that the physical association-dissociation of GLO and CAT, in response to environmental stress or stimuli, seems to serve as a specific mechanism to modulate H2O2 levels in rice. PMID:26900141

  1. Amperometric biosensors for glucose, lactate, and glycolate based on oxidases and redox-modified siloxane polymers

    NASA Astrophysics Data System (ADS)

    Hale, Paul D.; Inagaki, Toru; Lee, Hung Sui; Skotheim, Terje A.; Karan, Hiroko I.; Okamoto, Yoshi

    1989-06-01

    Amperometric biosensors based on flavin-containing oxidases undergo several steps which produce a measurable current that is related to the concentration of substrate. In the initial step, the substrate converts the oxidized flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN) into the reduced form FADH sub 2 or FMNH sub 2. Because these cofactors are located well within the enzyme molecule, direct electron transfer to the surface of a conventional electrode does not occur to a measurable degree. A common method of facilitating this electron transfer is to introduce oxygen into the system because it is the natural acceptor for the oxidases; the oxygen is reduced by the FADH sub 2 or FMNH sub 2 to hydrogen peroxide, which can then be detected electrochemically. The major drawback to this approach is the fact that oxidation of hydrogen peroxide requires a large overpotential, thus making these sensors susceptible to interference from electroactive species. To lower the necessary applied potential, several non-physiological redox couples have been employed to shuttle electrons between the flavin moieties and the electrode. The present paper describes the development of amperometric biosensors based on flavin-containing enzymes and a family of polymeric mediators.

  2. Amperometric biosensors for glucose, lactate, and glycolate based on oxidases and redox-modified siloxane polymers

    SciTech Connect

    Hale, P.D.; Inagaki, Toru; Lee, Hung Sui; Skotheim, T.A.; Karan, Hiroko I.; Okamoto, Yoshi; Medgar Evers Coll., Brooklyn, NY . Div. of Natural Science and Mathematics; Polytechnic Univ., Brooklyn, NY . Dept. of Chemistry)

    1989-01-01

    Amperometric biosensors based on flavin-containing oxidases undergo several steps which produce a measurable current that is related to the concentration of substrate. In the initial step, the substrate converts the oxidized flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN) into the reduced form (FADH{sub 2} or FMNH{sub 2}). Because these cofactors are located well within the enzyme molecule, direct electron transfer to the surface of a conventional electrode does not occur to a measurable degree. A common method of facilitating this electron transfer is to introduce oxygen into the system because it is the natural acceptor for the oxidases; the oxygen is reduced by the FADH{sub 2} or FMNH{sub 2} to hydrogen peroxide, which can then be detected electrochemically. The major drawback to this approach is the fact that oxidation of hydrogen peroxide requires a large overpotential, thus making these sensors susceptible to interference from electroactive species. To lower the necessary applied potential, several non-physiological redox couples have been employed to shuttle electrons between the flavin moieties and the electrode. For example, sensors based on the ferrocene/ferricinium redox couple and on electrodes consisting of conducting salts such as TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane) have previously been reported. Electron relays have also been attached directly to the enzyme molecule to facilitate electron transfer. More recently, these studies have been extended to include systems where the mediating redox species are covalently attached to polymers such as poly(pyrrole), poly(vinylpyridine), and poly(siloxane). The present paper describes the development of amperometric biosensors based on flavin-containing enzymes and this latter family of polymeric mediators. 9 refs., 5 figs.

  3. BOP: a basic phenylalanine-rich oligo-peptide located on the surface of glycolate oxidase influences its pI values.

    PubMed

    Xu, Jun; Du, Yingqing; Ma, Guangzhi; Xu, Jie

    2010-06-01

    Glycolate oxidase (GO) consists of identical subunits and therefore should show one definite pI value, but the isolated GO exhibited a range of pIs. This study investigated the underlying cause of this phenomenon. GO was purified and showed a molecular weight of 40 kDa by SDS-PAGE. Elution behavior on DEAE-cellulose chromatography and cellulose acetate membrane electrophoresis indicated that the purified GO was highly basic (pI>10.0). Repeated IEF and cIEF analysis showed that the pI of the purified GO was in the range of 10.0-3.25, either in a smear form or as distinct bands. 2-DE analysis showed that the 40 kDa subunit of GO displayed variable pIs from 9.6 to 3.65. It was likely that the purified GO was actually a complex consisted of GO and an unknown protein. CE-SDS, SDS-cellulose acetate membrane electrophoresis and amino acid compositions indicated that the unknown protein was a highly basic polymer (BP) consisting of basic and phenylalanine-rich oligo-peptide (BOP). Many BOPs are located on the surface of the acidic GO via ionic and hydrophobic interactions and formed GO-BOP complex (GC), resulting in a highly basic GC although GO itself was acidic. This hypothesis was further supported by the facts that anti-GC serum failed to recognize GO, and GC showed a peak at 257 nm although GO has few phenylalanine residues. Irregular and incomplete disassociation between GO and BOP was observed in IEF and cIEF, resulting in various intermediates with different ratios of GO/BOP, which could be the reason for the range of pIs observed for GO. PMID:20496344

  4. Reducing peanut allergens by high pressure combined with polyphenol oxidase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO) has been shown to reduce major peanut allergens (Ara h 1 and Ara h 2). Because high pressure (HP) can increase enzyme activity, we postulated that further reduction of peanut allergens can be achieved through HP combined with PPO. Peanut extracts were treated with each of th...

  5. Propylene Glycol Poisoning From Excess Whiskey Ingestion: A Case of High Osmolal Gap Metabolic Acidosis.

    PubMed

    Cunningham, Courtney A; Ku, Kevin; Sue, Gloria R

    2015-01-01

    In this report, we describe a case of high anion gap metabolic acidosis with a significant osmolal gap attributed to the ingestion of liquor containing propylene glycol. Recently, several reports have characterized severe lactic acidosis occurring in the setting of iatrogenic unintentional overdosing of medications that use propylene glycol as a diluent, including lorazepam and diazepam. To date, no studies have explored potential effects of excess propylene glycol in the setting of alcohol intoxication. Our patient endorsed drinking large volumes of cinnamon flavored whiskey, which was likely Fireball Cinnamon Whisky. To our knowledge, this is the first case of propylene glycol toxicity from an intentional ingestion of liquor containing propylene glycol. PMID:26904700

  6. A compact 100 kV high voltage glycol capacitor

    NASA Astrophysics Data System (ADS)

    Wang, Langning; Liu, Jinliang; Feng, Jiahuai

    2015-01-01

    A high voltage capacitor is described in this paper. The capacitor uses glycerol as energy storage medium, has a large capacitance close to 1 nF, can hold off voltages of up to 100 kV for μs charging time. Allowing for low inductance, the capacitor electrode is designed as coaxial structure, which is different from the common structure of the ceramic capacitor. With a steady capacitance at different frequencies and a high hold-off voltage of up to 100 kV, the glycol capacitor design provides a potential substitute for the ceramic capacitors in pulse-forming network modulator to generate high voltage pulses with a width longer than 100 ns.

  7. Temporal succession of putative glycolate-utilizing bacterioplankton tracks changes in dissolved organic matter in a high-elevation lake.

    PubMed

    Paver, Sara F; Nelson, Craig E; Kent, Angela D

    2013-03-01

    Shifts in the composition of dissolved organic matter (DOM) may be a principal factor effecting changes in bacterial community composition. Emerald Lake, a high-elevation lake with DOM dominated by terrestrial sources in the spring with increasing phytoplankton-derived inputs throughout the ice-free season, provided a natural experiment with which to investigate the importance of resource-mediated drivers. Glycolate-utilizing bacteria, a subset of the bacterial community able to use algal exudates, were characterized using DNA analysis of glycolate oxidase subunit D (glcD) genes from Emerald Lake samples collected approximately biweekly from ice-cover (June) through fall turnover (September). glcD genes were not detected in early-season samples when the lake was ice-covered and phytoplankton-derived resources were scarce. Following this period, glcD gene composition exhibited significant changes through time, which were strongly correlated with the combination of fluorescence index, an indicator of the proportion of lake vs. terrestrially derived DOM, and dissolved inorganic nitrate + nitrite. These results suggest that seasonal shifts in DOM source and environmental variables that affect the composition of algal-derived dissolved resources drive changes in the relative abundance and composition of putative glycolate-utilizing bacteria. These findings strengthen the evidence for shifts in DOM structuring bacterial communities. PMID:22984851

  8. Reducing peanut allergens by high pressure combined with polyphenol oxidase

    NASA Astrophysics Data System (ADS)

    Chung, Si-Yin; Houska, Milan; Reed, Shawndrika

    2013-12-01

    Polyphenol oxidase (PPO) has been shown to reduce major peanut allergens. Since high pressure (HP) can increase enzyme activity, we postulated that further reduction of peanut allergens can be achieved through HP combined with PPO. Peanut extracts containing caffeic acid were treated with each of the following: (1) HP; (2) HP+PPO; (3) PPO; and (4) none. HP was conducted at 300 and 500 MPa, each for 3 and 10 min, 37 °C. After treatment, SDS-PAGE was performed and allergenic capacity (IgE binding) was determined colorimetrically in inhibition enzyme-linked immunosorbent assay and Western blots, using a pooled plasma from peanut-allergic patients. Data showed that HP alone had no effect on major peanut allergens. However, HP at 500 MPa combined with PPO (HP500/PPO) induced a higher (approximately twofold) reduction of major peanut allergens and IgE binding than PPO alone or HP300/PPO. There was no difference between treatment times. We concluded that HP500/PPO at 3-min enhanced a twofold reduction of the allergenic capacity of peanut extracts, as compared to PPO itself.

  9. High concentrations of antibodies to xanthine oxidase in human and animal sera. Molecular characterization.

    PubMed Central

    Bruder, G; Jarasch, E D; Heid, H W

    1984-01-01

    The widespread occurrence of antibodies (IgG) specific to xanthine oxidase in both normal (nonimmune) human and animal sera, and in antisera raised against a diversity of unrelated antigens is described. A study of sera from 81 humans revealed that xanthine oxidase-specific IgG represents a high proportion (1-8%) of total IgG. No obvious correlation to pathological events or symptoms of disease could be found. These xanthine oxidase-specific antibodies could be isolated by immunoaffinity chromatography on purified human or bovine xanthine oxidase and showed specific binding to the enzyme polypeptide of Mr 155,000 in immunoblotting experiments. By immunofluorescence microscopy they displayed the same cell type-specific reaction as experimentally induced antibodies, i.e., the staining of lactating mammary gland epithelium and capillary endothelium. The naturally occurring xanthine oxidase-specific antibodies consisted of polyclonal IgG of various subclasses. F(ab')2 preparations gave immune-reactions identical to those of IgG. The human xanthine oxidase-specific IgG cross-reacted with the bovine enzyme and both human and animal antibodies partially inhibited its activity. The xanthine oxidase activity of human milk lipid globules and supernatant fractions from various human tissues was extremely low when compared with that of the bovine antigen. The enzyme protein, however, was effectively precipitated from these sources by both the human and bovine antibodies. We suggest that the exceptionally high concentrations of antibodies against one protein, xanthine oxidase, are due to self-immunization to the xanthine oxidase antigen present in endothelial cells of capillaries. We do not exclude, however, nutritional contributions of bovine milk antigen to the appearance of xanthine oxidase antibodies in human sera. The possible biological functions of this immunological reaction are discussed. Images PMID:6381540

  10. Determination of human plasma xanthine oxidase activity by high-performance liquid chromatography.

    PubMed

    Yamamoto, T; Moriwaki, Y; Takahashi, S; Tsutsumi, Z; Yamakita, J; Nasako, Y; Hiroishi, K; Higashino, K

    1996-06-01

    An assay for human plasma xanthine oxidase activity was developed with pterin as the substrate and the separation of product (isoxanthopterin) by high-performance liquid chromatography with a fluorescence detector. The reaction mixture consists of 60 microliters of plasma and 240 microliters of 0.2 M Tris-HCl buffer (pH 9.0) containing 113 microM pterin. With this assay, the activity of plasma xanthine oxidase could be easily determined despite its low activity. As a result, it could be demonstrated that the intravenous administration of heparin or the oral administration of ethanol did not increase plasma xanthine oxidase activity in normal subjects, and also that plasma xanthine oxidase activity was higher in patients with hepatitis C virus infection than in healthy subjects or patients with gout. In addition, a single patient with von Gierke's disease showed a marked increase in the plasma activity of this enzyme, relative to that apparent in normal subjects. PMID:8811453

  11. Cholesterol oxidase with high catalytic activity from Pseudomonas aeruginosa: Screening, molecular genetic analysis, expression and characterization.

    PubMed

    Doukyu, Noriyuki; Nihei, Shyou

    2015-07-01

    An extracellular cholesterol oxidase producer, Pseudomonas aeruginosa strain PA157, was isolated by a screening method to detect 6β-hydroperoxycholest-4-en-3-one-forming cholesterol oxidase. On the basis of a putative cholesterol oxidase gene sequence in the genome sequence data of P. aeruginosa strain PAO1, the cholesterol oxidase gene from strain PA157 was cloned. The mature form of the enzyme was overexpressed in Escherichia coli cells. The overexpressed enzyme formed inclusion bodies in recombinant E. coli cells grown at 20 °C and 30 °C. A soluble and active PA157 enzyme was obtained when the recombinant cells were grown at 10 °C. The purified enzyme was stable at pH 5.5 to 10 and was most active at pH 7.5-8.0, showing optimal activity at pH 7.0 and 70 °C. The enzyme retained about 90% of its activity after incubation for 30 min at 70 °C. The enzyme oxidized 3β-hydroxysteroids such as cholesterol, β-cholestanol, and β-sitosterol at high rates. The Km value and Vmax value for the cholesterol were 92.6 μM and 15.9 μmol/min/mg of protein, respectively. The Vmax value of the enzyme was higher than those of commercially available cholesterol oxidases. This is the first report to characterize a cholesterol oxidase from P. aeruginosa. PMID:25573142

  12. Film-forming properties of blends of high-oleic sunflower oil with polyalkyl glycol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The viscosity, density, and elastohydrodynamic film thicknesses of oil-soluble polyalkyl glycols (PAG), high oleic sunflower oil (HOSuO), and their 50/50 (wt.) blends were investigated. The viscosity and density of the blends were found to be predictable from the corresponding neat oil properties us...

  13. Effect of high pressure on peanut allergens in the presence of polyphenol oxidase and caffeic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High pressure (HP) enhances enzymatic reactions. Because polyphenol oxidase (PPO) is an enzyme, and reduces IgE binding of peanut allergens in presence of caffeic acid (CA), we postulated that a further reduction in IgE binding can be achieved, using HP together with PPO and CA. Peanut extracts cont...

  14. High-performance liquid chromatographic assays for protoporphyrinogen oxidase and ferrochelatase in human leucocytes.

    PubMed

    Guo, R; Lim, C K; Peters, T J

    1991-05-31

    Rapid, sensitive and specific high-performance liquid chromatographic assays are described for protoporphyrinogen oxidase and ferrochelatase in human leucocytes. The enzyme reaction products were separated and quantitated by reversed-phase high-performance liquid chromatography with fluorescence detection. The optimal pH for the protoporphyrinogen oxidase assay was 8.6 and the Michaelis constant for protoporphyrinogen IX was 9.78 +/- 0.96 microM (mean +/- S.D.). The mean (+/- S.D.) activity of protoporphyrinogen oxidase in fourteen apparently healthy subjects was 0.146 +/- 0.023 nmol protoporphyrin IX per min per mg protein. In one patient with variegate porphyria, the activity was 0.028 nmol protoporphyrin IX per min per mg protein. The optimal pH for ferrochelatase was 7.4 and with protoporphyrin and Zn2+ as substrates, the Michaelis constants were 1.49 and 8.33 microM, respectively. The mean activity of ferrochelatase in ten control subjects was 0.24 nM Zn-protoporphyrin or 2.05 nM Zn-mesoporphyrin formed per h per mg protein. PMID:1939451

  15. Separation of polyethylene glycols and amino-terminated polyethylene glycols by high-performance liquid chromatography under near critical conditions.

    PubMed

    Wei, Y-Z; Zhuo, R-X; Jiang, X-L

    2016-05-20

    The separation and characterization of polyethylene glycols (PEGs) and amino-substituted derivatives on common silica-based reversed-phase packing columns using isocratic elution is described. This separation is achieved by liquid chromatography under the near critical conditions (LCCC), based on the number of amino functional end groups without obvious effect of molar mass for PEGs. The mobile phase is acetonitrile in water with an optimal ammonium acetate buffer. The separation mechanism of PEG and amino-substituted PEG under the near LCCC on silica-based packing columns is confirmed to be ion-exchange interaction. Under the LCCC of PEG backbone, with fine tune of buffer concentration, the retention factor ratios for benzylamine and phenol in buffered mobile phases, α(benzylamine/phenol)-values, were used to assess the ion-exchange capacity on silica-based reversed-phase packing columns. To the best of our knowledge, this is the first report on separation of amino-functional PEGs independent of the molar mass by isocratic elution using common C18 or phenyl reversed-phase packing columns. PMID:27102303

  16. A tyrosinase with an abnormally high tyrosine hydroxylase/dopa oxidase ratio.

    PubMed

    Hernández-Romero, Diana; Sanchez-Amat, Antonio; Solano, Francisco

    2006-01-01

    The sequencing of the genome of Ralstonia solanacearum[Salanoubat M, Genin S, Artiguenave F, et al. (2002) Nature 415, 497-502] revealed several genes that putatively code for polyphenol oxidases (PPOs). This soil-borne pathogenic bacterium withers a wide range of plants. We detected the expression of two PPO genes (accession numbers NP_518458 and NP_519622) with high similarity to tyrosinases, both containing the six conserved histidines required to bind the pair of type-3 copper ions at the active site. Generation of null mutants in those genes by homologous recombination mutagenesis and protein purification allowed us to correlate each gene with its enzymatic activity. In contrast with all tyrosinases so far studied, the enzyme NP_518458 shows higher monophenolase than o-diphenolase activity and its initial activity does not depend on the presence of l-dopa cofactor. On the other hand, protein NP_519622 is an enzyme with a clear preference to oxidize o-diphenols and only residual monophenolase activity, behaving as a catechol oxidase. These catalytic characteristics are discussed in relation to two other characteristics apart from the six conserved histidines. One is the putative presence of a seventh histidine which interacts with the carboxy group on the substrate and controls the preference for carboxylated and decarboxylated substrates. The second is the size of the residue isosteric with the aromatic F261 reported in sweet potato catechol oxidase which acts as a gate to control accessibility to CuA at the active site. PMID:16403014

  17. Pulsed high-voltage dielectric properties of ethylene glycol/water mixtures

    NASA Astrophysics Data System (ADS)

    Fenneman, David B.

    1982-12-01

    Measurements of the (complex) dielectric constant, intrinsic time constant, and electrical breakdown strength of highly purified ethylene glycol/water mixtures as functions of temperature and mixture ratio are presented. Over the frequency range from 0.5 to 108 MHz, the dielectric constant is found to be well represented by a simple Debye model. When cooled to near their freezing points, these mixtures have dielectric constants of the same order as pure water (˜80) but with intrinsic time constants at least an order of magnitude greater than water. The mixtures are found to support fields greater than 15 MV/m for periods exceeding a millisecond. The observed high-voltage decay is nonsimple due to the phenomenon of charge injection. The ability to sustain high fields for millisecond time scales suggests the use of such mixtures as the dielectric in the pulse forming lines of large-pulse power machines.

  18. Glycolate metabolism in low and high CO sub 2 -grown chlorella pyrenoidosa and Pavlova lutheri as determined by sup 18 O-labeling

    SciTech Connect

    de Veau, E.J.; Burris, J.E. )

    1989-11-01

    Photorespiration in Chlorella pyrenoidosa Chick. was assayed by measuring {sup 18}O-labeled intermediates of the glycolate pathway. Glycolate, glycine, serine, and excreted glycolate were isolated and analyzed on a gas chromatograph/mass spectrometer to determine isotopic enrichment. Rates of glycolate synthesis were determined from {sup 18}O-labeling kinetics of the intermediates, pool sizes, derived rate equations, and nonlinear regression techniques. Glycolate synthesis was higher in high CO{sub 2}-grown cells than in air-grown cells when both were assayed under the same O{sub 2} and CO{sub 2} concentrations. Synthesis of glycolate, for both types of cells, was stimulated by high O{sub 2} levels and inhibited by high CO{sub 2} levels. Glycolate synthesis in 1.5% CO{sub 2}-grown Chlorella, when exposed to a 0.035% CO{sub 2} atmosphere, increased from about 41 to 86 nanomoles per milligram chlorophyll per minute when the O{sub 2} concentration was increased from 21 to 40%. Glycolate synthesis in air-grown cells increased from 2 to 6 nanomoles per milligram chlorophyll per minute under the same gas levels. Synthesis was undetectable when either the O{sub 2} concentration was lowered to 2% or the CO{sub 2}-concentration was raised to 1.5%. Glycolate excretion was also sensitive to O{sub 2} and CO{sub 2} concentrations in 1.5% CO{sub 2}-grown cells and the glycolate that was excreted was {sup 18}O-labeled. Air-grown cells did not excrete glycolate under any experimental condition. Indirect evidence indicated that glycolate may be excreted as a lactone in Chlorella. Photorespiratory {sup 18}O-labeling kinetics were determined for Pavlova lutheri, which unlike Chlorella and higher plants did not directly synthesize glycine and serine from glycolate. This alga did excrete a significant proportion of newly synthesized glycolate into the media.

  19. Barium Titanate Nanoparticles: Highly Cytocompatible Dispersions in Glycol-chitosan and Doxorubicin Complexes for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Ciofani, Gianni; Danti, Serena; D'Alessandro, Delfo; Moscato, Stefania; Petrini, Mario; Menciassi, Arianna

    2010-07-01

    In the latest years, innovative nanomaterials have attracted a dramatic and exponentially increasing interest, in particular for their potential applications in the biomedical field. In this paper, we reported our findings on the cytocompatibility of barium titanate nanoparticles (BTNPs), an extremely interesting ceramic material. A rational and systematic study of BTNP cytocompatibility was performed, using a dispersion method based on a non-covalent binding to glycol-chitosan, which demonstrated the optimal cytocompatibility of this nanomaterial even at high concentration (100 μg/ml). Moreover, we showed that the efficiency of doxorubicin, a widely used chemotherapy drug, is highly enhanced following the complexation with BTNPs. Our results suggest that innovative ceramic nanomaterials such as BTNPs can be realistically exploited as alternative cellular nanovectors.

  20. A Highly Stable D-Amino Acid Oxidase of the Thermophilic Bacterium Rubrobacter xylanophilus.

    PubMed

    Takahashi, Shouji; Furukawara, Makoto; Omae, Keishi; Tadokoro, Namiho; Saito, Yayoi; Abe, Katsumasa; Kera, Yoshio

    2014-12-01

    d-Amino acid oxidase (DAO) is a biotechnologically attractive enzyme that can be used in a variety of applications, but its utility is limited by its relatively poor stability. A search of a bacterial genome database revealed a gene encoding a protein homologous to DAO in the thermophilic bacterium Rubrobacter xylanophilus (RxDAO). The recombinant protein expressed in Escherichia coli was a monomeric protein containing noncovalently bound flavin adenine dinucleotide as a cofactor. This protein exhibited oxidase activity against neutral and basic d-amino acids and was significantly inhibited by a DAO inhibitor, benzoate, but not by any of the tested d-aspartate oxidase (DDO) inhibitors, thus indicating that the protein is DAO. RxDAO exhibited higher activities and affinities toward branched-chain d-amino acids, with the highest specific activity toward d-valine and catalytic efficiency (kcat/Km) toward d-leucine. Substrate inhibition was observed in the case of d-tyrosine. The enzyme had an optimum pH range and temperature of pH 7.5 to 10 and 65°C, respectively, and was stable between pH 5.0 and pH 8.0, with a T50 (the temperature at which 50% of the initial enzymatic activity is lost) of 64°C. No loss of enzyme activity was observed after a 1-week incubation period at 30°C. This enzyme was markedly inactivated by phenylmethylsulfonyl fluoride but not by thiol-modifying reagents and diethyl pyrocarbonate, which are known to inhibit certain DAOs. These results demonstrated that RxDAO is a highly stable DAO and suggested that this enzyme may be valuable for practical applications, such as the determination and quantification of branched-chain d-amino acids, and as a scaffold to generate a novel DAO via protein engineering. PMID:25217016

  1. A Highly Stable d-Amino Acid Oxidase of the Thermophilic Bacterium Rubrobacter xylanophilus

    PubMed Central

    Furukawara, Makoto; Omae, Keishi; Tadokoro, Namiho; Saito, Yayoi; Abe, Katsumasa; Kera, Yoshio

    2014-01-01

    d-Amino acid oxidase (DAO) is a biotechnologically attractive enzyme that can be used in a variety of applications, but its utility is limited by its relatively poor stability. A search of a bacterial genome database revealed a gene encoding a protein homologous to DAO in the thermophilic bacterium Rubrobacter xylanophilus (RxDAO). The recombinant protein expressed in Escherichia coli was a monomeric protein containing noncovalently bound flavin adenine dinucleotide as a cofactor. This protein exhibited oxidase activity against neutral and basic d-amino acids and was significantly inhibited by a DAO inhibitor, benzoate, but not by any of the tested d-aspartate oxidase (DDO) inhibitors, thus indicating that the protein is DAO. RxDAO exhibited higher activities and affinities toward branched-chain d-amino acids, with the highest specific activity toward d-valine and catalytic efficiency (kcat/Km) toward d-leucine. Substrate inhibition was observed in the case of d-tyrosine. The enzyme had an optimum pH range and temperature of pH 7.5 to 10 and 65°C, respectively, and was stable between pH 5.0 and pH 8.0, with a T50 (the temperature at which 50% of the initial enzymatic activity is lost) of 64°C. No loss of enzyme activity was observed after a 1-week incubation period at 30°C. This enzyme was markedly inactivated by phenylmethylsulfonyl fluoride but not by thiol-modifying reagents and diethyl pyrocarbonate, which are known to inhibit certain DAOs. These results demonstrated that RxDAO is a highly stable DAO and suggested that this enzyme may be valuable for practical applications, such as the determination and quantification of branched-chain d-amino acids, and as a scaffold to generate a novel DAO via protein engineering. PMID:25217016

  2. High-frequency fusion of Streptomyces parvulus or Streptomyces antibioticus protoplasts induced by polyethylene glycol.

    PubMed Central

    Ochi, K; Hitchcock, M J; Katz, E

    1979-01-01

    Conditions were established for the regeneration of protoplasts of Streptomyces parvulus and Streptomyces antibioticus to the mycelial form. Regeneration was accomplished with a hypertonic medium that contained sucrose, CaCl2, MgCl2, and low levels of phosphate. High-frequency fusion of protoplasts derived from auxotrophic strains of S. parvulus or S. antibioticus was induced by polyethylene glycol 4,000 (42%, wt/vol). The frequency of genetic transfer by the fusogenic procedure varied with the auxotrophic strains examined. Fusion with auxotrophic strains of S. parvulus resulted in the formation of true prototrophic recombinants. Similar studies with S. antibioticus revealed that both stable prototrophic recombinants and heterokaryons were formed. PMID:479112

  3. [Determination of isophthalic acid in polyethylene glycol terephthalate fiber by high performance liquid chromatography].

    PubMed

    Wang, R; Wang, X Y; Tang, C J; Li, L P

    2001-07-01

    The isophthalic acid(IPA) is present in polyethylene glycol terephthalate(PET) at small level, but plays an important role for the properties of polyester fiber. Thus the PET sample was hydrolysated by 100 g/L of sodium hydrate in methanol at 70 degrees C during 10 h and finally assayed by HPLC. A reversed-phase high performance liquid chromatographic method for the separation of isophthalic acid from terephthalic acid(TPA) has been developed. The operating conditions were Novapak C18 column, methanol-water(15:85, V/V)(pH3) as mobile phase with the flow rate of 1.0 mL/min and UV detection wavelength at 254 nm. PMID:12545507

  4. Variations in the alternative oxidase in chlamydomonas grown in air or high CO sub 2

    SciTech Connect

    Goyal, A.; Tolbert, N.E. )

    1989-03-01

    Chlamydomonas in the resting phase of growth has an equal capacity of about 15 micromole O{sub 2} uptake per hour per milligram of chlorophyll for both the cytochrome c, CN-sensitive respiration, and for the alternative, salicylhydroxamic acid-sensitive respiration. Alternative respiration capacity was measured as salicylhydroxamic acid inhibited O{sub 2} uptake in the presence of CN, and cytochrome c respiration capacity as CN inhibition of O{sub 2} uptake in the presence of salicylhydroxamic acid. Measured total respiration was considerably less than the combined capacities for respiration. During the log phase of growth on high (2-5%) CO{sub 2}, the alternative respiration capacity decreased about 90% but returned as the culture entered the lag phase. When the alternative oxidase capacity was low, addition of salicylic acid or cyanide induced its reappearance. When cells were grown on low (air-level) CO{sub 2}, which induced a CO{sub 2} concentrating mechanism, the alternative oxidase capacity did not decrease during the growth phase. Attempts to measure in vivo distribution of respiration between the two pathways with either CN or salicylhydroxamic acid alone were inconclusive.

  5. Development of Modified Pag (Polyalkylene Glycol) High VI High Fuel Efficient Lubricant for LDV Applications

    SciTech Connect

    Gangopadhyay, Arup; McWatt, D. G.; Zdrodowski, R. J.; Liu, Zak; Elie, Larry; Simko, S. J.; Erdemir, Ali; Ramirez, Giovanni; Cuthbert, J.; Hock, E. D.

    2015-09-30

    Engine oils play a critical role in friction reduction. Improvements in engine oil technology steadily improved fuel economy as the industry moved through ILSAC GF-1 to GF-5 specifications. These improvements were influenced by changes in base oil chemistry, development of new friction modifiers and their treat levels, and the total additive package consisting of various other components. However, the improvements are incremental and further fuel consumption reduction opportunities are becoming more challenging. Polyalkylene glycol (PAG) based engine oils are being explored as a step forward for significant fuel consumption reduction. Although PAG fluids are used in many industrial applications, its application as an engine oil has been explored in a limited way. The objective of this project is to deep dive in exploring the applicability of PAG technology in engine oil, understanding the benefits, and limitations, elucidating the mechanism(s) for friction benefits, if any, and finally recommending how to address any limitations. The project was designed in four steps, starting with selection of lubricant technology, followed by friction and wear evaluations in laboratory bench tests which are relatively simple and inexpensive and also served as a screener for further evaluation. Selected formulations were chosen for more complex engine component level tests i.e., motored valvetrain friction and wear, piston ring friction using a motored single cylinder, and motored engine tests. A couple of formulations were further selected based on component level tests for engine dyno tests i.e., Sequence VID (ASTM D6709) for fuel economy, Sequence IVA (ASTM D6891) for valvetrain wear, and Sequence VG (ASTM D6593) for sludge and varnish protection. These are some of the industry standard tests required for qualifying engine oils. Out of these tests, a single PAG oil was selected for chassis roll dynamometer tests for fuel economy and emission measurements using FTP (Federal

  6. Tea polyphenols alleviate high fat and high glucose-induced endothelial hyperpermeability by attenuating ROS production via NADPH oxidase pathway

    PubMed Central

    2014-01-01

    Background Hyperglycemia-induced endothelial hyperpermeability is crucial to cardiovascular disorders and macro-vascular complications in diabetes mellitus. The objective of this study is to investigate the effects of green tea polyphenols (GTPs) on endothelial hyperpermeability and the role of nicotinamide adenine dinucleotide phosphate (NADPH) pathway. Methods Male Wistar rats fed on a high fat diet (HF) were treated with GTPs (0, 0.8, 1.6, 3.2 g/L in drinking water) for 26 weeks. Bovine aortic endothelial cells (BAECs) were treated with high glucose (HG, 33 mmol/L) and GTPs (0.0, 0.4, or 4 μg/mL) for 24 hours in vitro. The endothelial permeabilities in rat aorta and monolayer BAECs were measured by Evans blue injection method and efflux of fluorescein isothiocyanate (FITC)-dextran, respectively. The reactive oxygen species (ROS) levels in rat aorta and monolayer BAECs were measured by dihydroethidium (DHE) and 2′, 7′-dichloro-fluorescein diacetate (DCFH-DA) fluorescent probe, respectively. Protein levels of NADPH oxidase subunits were determined by Western-blot. Results HF diet-fed increased the endothelial permeability and ROS levels in rat aorta while HG treatments increased the endothelial permeability and ROS levels in cultured BAECs. Co-treatment with GTPs alleviated those changes both in vivo and in vitro. In in vitro studies, GTPs treatments protected against the HG-induced over-expressions of p22phox and p67phox. Diphenylene iodonium chloride (DPI), an inhibitor of NADPH oxidase, alleviated the hyperpermeability induced by HG. Conclusions GTPs could alleviate endothelial hyperpermeabilities in HF diet-fed rat aorta and in HG treated BAECs. The decrease of ROS production resulting from down-regulation of NADPH oxidase contributed to the alleviation of endothelial hyperpermeability. PMID:24580748

  7. Protective Effect of Intravenous High Molecular Weight Polyethylene Glycol on Fatty Liver Preservation

    PubMed Central

    Bejaoui, Mohamed; Pantazi, Eirini; Folch-Puy, Emma; Panisello, Arnau; Calvo, María; Pasut, Gianfranco; Rimola, Antoni; Navasa, Miquel; Adam, René; Roselló-Catafau, Joan

    2015-01-01

    Ischemia reperfusion injury (IRI) leads to significant tissue damage in liver surgery. Polyethylene glycols (PEGs) are water soluble nontoxic polymers that have proved their effectiveness against IRI. The objective of our study was to investigate the potential protective effects of intravenous administration of a high molecular weight PEG of 35 kDa (PEG 35) in steatotic livers subjected to cold ischemia reperfusion. In this study, we used isolated perfused rat liver model to assess the effects of PEG 35 intravenous administration after prolonged cold ischemia (24 h, 4°C) and after reperfusion (2 h, 37°C). Liver injury was measured by transaminases levels and mitochondrial damage was determined by confocal microscopy assessing mitochondrial polarization (after cold storage) and by measuring glutamate dehydrogenase activity (after reperfusion). Also, cell signaling pathways involved in the physiopathology of IRI were assessed by western blot technique. Our results show that intravenous administration of PEG 35 at 10 mg/kg ameliorated liver injury and protected the mitochondria. Moreover, PEG 35 administration induced a significant phosphorylation of prosurvival protein kinase B (Akt) and activation of cytoprotective factors e-NOS and AMPK. In conclusion, intravenous PEG 35 efficiently protects steatotic livers exposed to cold IRI. PMID:26543868

  8. Implementation of tetra-poly(ethylene glycol) hydrogel with high mechanical strength into microfluidic device technology

    PubMed Central

    Takehara, Hiroaki; Nagaoka, Akira; Noguchi, Jun; Akagi, Takanori; Sakai, Takamasa; Chung, Ung-il; Kasai, Haruo; Ichiki, Takanori

    2013-01-01

    Hydrogels have several excellent characteristics suitable for biomedical use such as softness, biological inertness and solute permeability. Hence, integrating hydrogels into microfluidic devices is a promising approach for providing additional functions such as biocompatibility and porosity, to microfluidic devices. However, the poor mechanical strength of hydrogels has severely limited device design and fabrication. A tetra-poly(ethylene glycol) (tetra-PEG) hydrogel synthesized recently has high mechanical strength and is expected to overcome such a limitation. In this research, we have comprehensively studied the implementation of tetra-PEG gel into microfluidic device technology. First, the fabrication of tetra-PEG gel/PDMS hybrid microchannels was established by developing a simple and robust bonding technique. Second, some fundamental features of tetra-PEG gel/PDMS hybrid microchannels, particularly fluid flow and mass transfer, were studied. Finally, to demonstrate the unique application of tetra-PEG-gel-integrated microfluidic devices, the generation of patterned chemical modulation with the maximum concentration gradient: 10% per 20 μm in a hydrogel was performed. The techniques developed in this study are expected to provide fundamental and beneficial methods of developing various microfluidic devices for life science and biomedical applications. PMID:24404072

  9. Highly efficient SO₂ absorption and its subsequent utilization by weak base/polyethylene glycol binary system.

    PubMed

    Yang, Zhen-Zhen; He, Liang-Nian; Zhao, Ya-Nan; Yu, Bing

    2013-02-01

    A binary system consisting of polyethylene glycol (PEG, proton donor)/PEG-functionalized base with suitable basicity was developed for efficient gas desulfurization (GDS) and can be regarded as an alternative approach to circumvent the energy penalty problem in the GDS process. High capacity for SO(2) capture up to 4.88 mol of SO(2)/mol of base was achieved even under low partial pressure of SO(2). Furthermore, SO(2) desorption runs smoothly under mild conditions (N(2), 25 °C) and no significant drop in SO(2) absorption was observed after five-successive absorption-desorption cycles. On the other hand, the absorbed SO(2) by PEG(150)MeIm/PEG(150), being considered as the activated form of SO(2), can be directly transformed into value-added chemicals under mild conditions, thus eliminating the energy penalty for SO(2) desorption and simultaneously realizing recycle of the absorbents. Thus, this SO(2) capture and utilization (SCU) process offers an alternative way for GDS and potentially enables the SO(2) conversion from flue gas to useful chemicals as a value-added process. PMID:23323771

  10. Highly conductive polymer electrolyte membranes modified with polyethylene glycol-bis-carbamate

    NASA Astrophysics Data System (ADS)

    Fu, Guopeng; Dempsey, Janel; Kyu, Thein

    By virtue of its non-flammability and chemical stability, polyethylene glycol (PEG) networks have shown potential application in all solid-state polymer electrolyte membranes (PEM). However, room temperature ionic conductivity of these PEG based PEMs is inherently low. Plasticization of these PEMs is needed to improve the ionic conductivity. It was demonstrated by this group that small-molecule plasticizers such as succinonitrile, ethylene carbonate, or urea-carbamate can boost ionic conductivity of solid-state polymer electrolyte membranes. Polyethylene glycol bis-carbamate (PEGBC) was synthesized via condensation reaction of polyethylene glycol diamine and ethylene carbonate. The PEGBC modified PEM has shown higher ionic conductivity relative to the unmodified PEM. Moreover, PEGBC modified PEM has a better thermal stability relative to ethylene carbonate based liquid electrolyte with enhanced ionic conductivity. Supported by NSF-DMR 1161070, 1502543 and REU 1359321.

  11. Blueberry polyphenol oxidase: Characterization and the kinetics of thermal and high pressure activation and inactivation.

    PubMed

    Terefe, Netsanet Shiferaw; Delon, Antoine; Buckow, Roman; Versteeg, Cornelis

    2015-12-01

    Partially purified blueberry polyphenol oxidase (PPO) in Mcllvaine buffer (pH=3.6, typical pH of blueberry juice) was subjected to processing at isothermal-isobaric conditions at temperatures from 30 to 80 °C and pressure from 0.1 to 700 MPa. High pressure processing at 30-50 °C at all pressures studied caused irreversible PPO activity increase with a maximum of 6.1 fold increase at 500 MPa and 30 °C. Treatments at mild pressure-mild temperature conditions (0.1-400 MPa, 60 °C) also caused up to 3 fold PPO activity increase. Initial activity increase followed by a decrease occurred at relatively high pressure-mild temperature (400-600 MPa, 60 °C) and mild pressure-high temperature (0.1-400 MPa, 70-80 °C) combinations. At temperatures higher than 76 °C, monotonic decrease in PPO activity occurred at 0.1 MPa and pressures higher than 500 MPa. The activation/inactivation kinetics of the enzyme was successfully modelled assuming consecutive reactions in series with activation followed by inactivation. PMID:26041182

  12. Cell-free protein synthesis enables high yielding synthesis of an active multicopper oxidase.

    PubMed

    Li, Jian; Lawton, Thomas J; Kostecki, Jan S; Nisthal, Alex; Fang, Jia; Mayo, Stephen L; Rosenzweig, Amy C; Jewett, Michael C

    2016-02-01

    Multicopper oxidases (MCOs) are broadly distributed in all kingdoms of life and perform a variety of important oxidative reactions. These enzymes have potential biotechnological applications; however, the applications are impeded by low expression yields in traditional recombinant hosts, solubility issues, and poor copper cofactor assembly. As an alternative to traditional recombinant protein expression, we show the ability to use cell-free protein synthesis (CFPS) to produce complex MCO proteins with high soluble titers. Specifically, we report the production of MCOs in an Escherichia coli-based cell-free transcription-translation system. Total yields as high as 1.2 mg mL(-1) were observed after a 20-h batch reaction. More than 95% of the protein was soluble and activity was obtained by simple post-CFPS addition of copper ions in the form of CuSO4 . Scale-up reactions were achieved from 15 to 100 µL without a decrease in productivity and solubility. CFPS titers were higher than in vivo expression titers and more soluble, avoiding the formation of inclusion bodies. Our work extends the utility of the cell-free platform to the production of active proteins containing copper cofactors and demonstrates a simple method for producing MCOs. PMID:26356243

  13. Polyethylene Glycol-Mediated Synthesis of Cubic Iron Oxide Nanoparticles with High Heating Power.

    PubMed

    Iacovita, Cristian; Stiufiuc, Rares; Radu, Teodora; Florea, Adrian; Stiufiuc, Gabriela; Dutu, Alina; Mican, Sever; Tetean, Romulus; Lucaciu, Constantin M

    2015-12-01

    Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent. The as-synthesized IOMNPs are poly-dispersed, highly crystalline, and exhibit a cubic shape. The size of IOMNPs is strongly dependent on the reaction time and the ration between the amount of magnetic precursor and PEG200 used in the synthesis method. At low magnetic precursor/PEG200 ratio, the cubic IOMNPs coexist with polyhedral IOMNPs. The structure and morphology of the IOMNPs were thoroughly investigated by using a wide range of techniques: TEM, XRD, XPS, FTIR, and RAMAN. XPS analysis showed that the IOMNPs comprise a crystalline magnetite core bearing on the outer surface functional groups from PEG200 and acetate. The presence of physisorbed PEG200 on the IOMNP surface is faintly detected through FT-IR spectroscopy. The surface of IOMNPs undergoes oxidation into maghemite as proven by RAMAN spectroscopy and the occurrence of satellite peaks in the Fe2p XP spectra. The magnetic studies performed on powder show that the blocking temperature (TB) of IOMNPs is around 300 K displaying a coercive field in between 160 and 170 Oe. Below the TB, the field-cooled (FC) curves turn concave and describe a plateau indicating that strong magnetic dipole-dipole interactions are manifested in between IOMNPs. The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water. The SAR dependence on the applied magnetic field, studied up to magnetic field amplitude of 60 kA/m, presents a sigmoid shape with saturation values up to 1700 W/g. By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs. PMID:26446074

  14. Polyethylene Glycol-Mediated Synthesis of Cubic Iron Oxide Nanoparticles with High Heating Power

    NASA Astrophysics Data System (ADS)

    Iacovita, Cristian; Stiufiuc, Rares; Radu, Teodora; Florea, Adrian; Stiufiuc, Gabriela; Dutu, Alina; Mican, Sever; Tetean, Romulus; Lucaciu, Constantin M.

    2015-10-01

    Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent. The as-synthesized IOMNPs are poly-dispersed, highly crystalline, and exhibit a cubic shape. The size of IOMNPs is strongly dependent on the reaction time and the ration between the amount of magnetic precursor and PEG200 used in the synthesis method. At low magnetic precursor/PEG200 ratio, the cubic IOMNPs coexist with polyhedral IOMNPs. The structure and morphology of the IOMNPs were thoroughly investigated by using a wide range of techniques: TEM, XRD, XPS, FTIR, and RAMAN. XPS analysis showed that the IOMNPs comprise a crystalline magnetite core bearing on the outer surface functional groups from PEG200 and acetate. The presence of physisorbed PEG200 on the IOMNP surface is faintly detected through FT-IR spectroscopy. The surface of IOMNPs undergoes oxidation into maghemite as proven by RAMAN spectroscopy and the occurrence of satellite peaks in the Fe2p XP spectra. The magnetic studies performed on powder show that the blocking temperature (TB) of IOMNPs is around 300 K displaying a coercive field in between 160 and 170 Oe. Below the TB, the field-cooled (FC) curves turn concave and describe a plateau indicating that strong magnetic dipole-dipole interactions are manifested in between IOMNPs. The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water. The SAR dependence on the applied magnetic field, studied up to magnetic field amplitude of 60 kA/m, presents a sigmoid shape with saturation values up to 1700 W/g. By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs.

  15. Antioxidants inhibition of high plasma androgenic markers in the pathogenesis of ethylene glycol (EG)-induced nephrolithiasis in Wistar rats.

    PubMed

    Naghii, Mohammad Reza; Mofid, Mahmood; Hedayati, Mehdi; Khalagi, Kazem

    2014-04-01

    The association between serum gonadal steroids and urolithiasis in males received only limited attention. Calcium oxalate urolithiasis is induced by administration of ethylene glycol in drinking water. It appears that the administration of natural antioxidants has been used to protect against nephrolithiasis in human and experimental animals. The purpose is to study the potential role of antioxidants as inhibitors of high plasma androgenic markers or hyperandrogenicity in the pathogenesis of ethylene glycol-induced nephrolithiasis in Wistar rats. Male Wistar rats were studied in 4-week period. Group 1 (control) was fed a standard commercial diet. Group 2 received the same diet with 0.5 % of ethylene glycol. Group 3 received EG plus the diet and water added with antioxidant nutrients and lime juice as the dietary source of citrate. Group 4 and Group 5 were treated similar to Group 2 and Group 3 with 0.75 % of ethylene glycol. For antioxidant supplementation, the standard diet enriched with 4,000.0 μg vitamin E and 1,500.0 IU vitamin A for each rat per day added to the diet once a week, and provided daily with 5.0 mg vitamin C, 400.0 μg vitamin B6, 20.0 μg selenium, 12.0 mg zinc, and 2.0 mg boron for each rat per day in their drinking water. After treatment period, collection of blood was performed and kidneys were removed and used for histopathological examination. The results based on various assays, measuring size of crystal deposition, and histological examinations showed that high concentration of androgens acts as promoter for the formation of renal calculi due to ethylene glycol consumption and the inhibitory role of antioxidant complex in the formation of renal calculi disease. Data revealed that the size and the mean number of crystal deposits determined in EG 0.75 % treated groups (G4) were significantly higher than the EG-treated groups, added with antioxidant nutrients and lime juice (G5). The mean concentration of androgens in Group 4 increased after

  16. Effect of Acute Xanthine Oxidase Inhibition on Myocardial Energetics During Basal and Very High Cardiac Workstates

    PubMed Central

    Lee, Joseph; Hu, Qingsong; Mansoor, Abdul; Kamdar, Forum

    2014-01-01

    Myocardial ischemia is associated with reduced myocardial adenosine triphosphate (ATP) and increased free adenosine diphosphate (ADP) similar to the normal heart at very high cardiac workstates (HCW). We examined whether acute xanthine oxidase inhibition (XOI) in vivo can decrease myocardial free ADP in normal hearts functioning at basal cardiac workstates (BCW) or very HCW (catecholamine-induced). Myocardial high-energy phosphate (31P magnetic resonance spectroscopy), blood flow (radioactive microspheres), and oxygen consumption (MVO2) were measured in an open-chest canine model before and after infusion of vehicle or an XO inhibitor (allopurinol or febuxostat; n= 10 in each group) during BCW and infusion of dobutamine + dopamine to induce a very HCW. During BCW, both allopurinol and febuxostat resulted in higher phosphocreatine (PCr)/ATP, corresponding to lower ADP levels. During vehicle infusion, HCW caused a decrease of PCr/ATP and an increase in myocardial free ADP. Although XOI did not prevent an increase in free ADP during catecholamine infusion, the values in the allopurinol or febuxostat groups (0.141±0.012 and 0.136±0.011 μmol/g dry wt, respectively) remained significantly less than in the vehicle group (0.180±0.017; P<0.05). Thus, at a given rate of ATP synthesis, XOI decreased the free ADP level needed to drive ATP synthesis, suggesting a more energy-efficient status. As contractile dysfunction in ischemia is characterized by increase of myocardial free ADP and energy deficiency, the data suggest that XOI might be a potential therapy for improving energy efficiency during myocardial ischemia. PMID:21584861

  17. Ethylene glycol

    Integrated Risk Information System (IRIS)

    Ethylene glycol ; CASRN 107 - 21 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  18. Propylene glycol

    Integrated Risk Information System (IRIS)

    Propylene glycol ; CASRN 57 - 55 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  19. High-resolution structures of cholesterol oxidase in the reduced state provide insights into redox stabilization.

    PubMed

    Golden, Emily; Karton, Amir; Vrielink, Alice

    2014-12-01

    Cholesterol oxidase (CO) is a flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. The reductive half reaction occurs via a hydride transfer from the substrate to the FAD cofactor. The structures of CO reduced with dithionite under aerobic conditions and in the presence of the substrate 2-propanol under both aerobic and anaerobic conditions are presented. The 1.32 Å resolution structure of the dithionite-reduced enzyme reveals a sulfite molecule covalently bound to the FAD cofactor. The isoalloxazine ring system displays a bent structure relative to that of the oxidized enzyme, and alternate conformations of a triad of aromatic residues near to the cofactor are evident. A 1.12 Å resolution anaerobically trapped reduced enzyme structure in the presence of 2-propanol does not show a similar bending of the flavin ring system, but does show alternate conformations of the aromatic triad. Additionally, a significant difference electron-density peak is observed within a covalent-bond distance of N5 of the flavin moiety, suggesting that a hydride-transfer event has occurred as a result of substrate oxidation trapping the flavin in the electron-rich reduced state. The hydride transfer generates a tetrahedral geometry about the flavin N5 atom. High-level density-functional theory calculations were performed to correlate the crystallographic findings with the energetics of this unusual arrangement of the flavin moiety. These calculations suggest that strong hydrogen-bond interactions between Gly120 and the flavin N5 centre may play an important role in these structural features. PMID:25478834

  20. High throughput Screening to Identify Natural Human Monoamine Oxidase B Inhibitors

    PubMed Central

    Mazzio, E; Deiab, S; Park, K; Soliman, KFA

    2012-01-01

    Age-related increase in monoamine oxidase B (MAO-B) may contribute to CNS neurodegenerative diseases. Moreover, MAO-B inhibitors are used in the treatment of idiopathic Parkinson disease as preliminary monotherapy or adjunct therapy with L-dopa. To date, meager natural sources of MAO-B inhibitors have been identified, and the relative strength, potency and rank of many plants relative to standard drugs such as Selegiline (L-deprenyl, Eldepryl) are not known. In this work, we developed and utilized a high throughput enzyme microarray format to screen and evaluate 905 natural product extracts (0.025–.7 mg/ml) to inhibit human MAO-B derived from BTI-TN-5B1-4 cells infected with recombinant baculovirus. The protein sequence of purified enzyme was confirmed using 1D gel electrophoresis-matrix assisted laser desorption ionization-time-of-flight-tandem mass spectroscopy, and enzyme activity was confirmed by [1] substrate conversion (3-mM benzylamine) to H202 and [2] benzaldehyde. Of the 905 natural extracts tested, the lowest IC50s [<0.07 mg/ml] were obtained with extracts of Amur Corktree (Phellodendron amurense), Bakuchi Seed(Cyamopsis psoralioides), Licorice Root (Glycyrrhiza glabra/uralensis), Babchi (Psoralea corylifolia seed). The data also show, albeit to a lesser extent, inhibitory properties of herbs originating from the mint family (Lamiaceae) and Turmeric, Comfrey, Bringraj, Skullcap, Kava-kava, Wild Indigo, Gentian and Green Tea. In conclusion, the data reflect relative potency information by rank of commonly used herbs and plants that contain human MAO-B inhibitory properties in their natural form. PMID:22887993

  1. Hydrogen peroxide generated by NADPH oxidase is involved in high blue-light-induced chloroplast avoidance movements in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Wen, Feng; Xing, Da; Zhang, Lingrui

    2009-08-01

    One of the most important functions of blue light is to induce chloroplast movements by reducing the damage to photosynthetic machinery under excess light. Hydrogen peroxide (H2O2), generated by various environmental stimuli, can act as a signaling molecule that regulates a number of developmental processes and environmental responses. To investigate whether H2O2 is involved in high blue light-induced chloroplast avoidance movements, we use luminescence spectrometer to observe H2O2 generation with the assistance of the fluorescence probe dichlorofluorescin diacetate (H2DCF-DA). After treatment with high blue light, a large quantity of H2O2 indicated by the fluorescence intensity of DCF is produced in a dose-dependent manner in leaf strip of Arabidopsis. Enzymatic assay shows that the activity of NADPH oxidase, which is a major site for H2O2 generation, also rapidly increases in treated strips. Exogenously applied H2O2 can promote the high blue light-induced chloroplast movements. Moreover, high blue light-induced H2O2 generation can be abolished completely by addition of exogenous catalase (CAT), and partly by diphenylene iodonium (DPI) and dichlorophenyl dimethylurea (DCMU), which are an NADPH oxidase inhibitor and a blocker of electron transport chain. And subsequent chloroplast movements can be abolished by CAT and DPI, but not by DCMU. These results presented here suggested that high blue light can induce oxidative burst, and NADPH oxidase as a major producer for H2O2 is involved in blue light-induced chloroplast avoidance movements.

  2. Banking of non-viable skin allografts using high concentrations of glycerol or propylene glycol.

    PubMed

    Huang, Qizhi; Pegg, David E; Kearney, John N

    2004-01-01

    The aims of this study were to investigate the kinetics of the current glycerol banking method for the preservation of non-viable skin allografts; to improve it with respect to efficiency and microbial safety; and to investigate the possibility of using propylene glycol in place of glycerol to provide a more rapid process. Skin grafts were preserved in 98% v/v glycerol (GLY) according to the method used in the Sheffield Skin Bank. During the addition and removal processes, the amounts of GLY and water in the skin were determined using the Karl Fischer method and HPLC respectively. Propylene glycol (PG) was investigated as an alternative to glycerol with the object of shortening the process. To avoid the need for prolonged storage in glycerol to disinfect the tissue, and to improve the effectiveness of disinfection, exposure to peracetic acid (PAA) was included and its influence on the kinetics of the preservation process was evaluated. The histological and ultrastructural appearances of skin that had been banked by these methods was also investigated. It was found that the permeation of GLY in skin probably involves two processes: diffusion and binding; the rate of transport was attenuated as the GLY concentration in the skin increased. The current incubation time could be shortened, but an inconveniently prolonged washout process was required. The substitution of PG for GLY accelerated the whole process, particularly the removal process, making the method more convenient for the emergency use of skin grafts in the clinic. The penetration of PG also involved diffusion and binding, but there was no attenuation of transport as the concentration increased. The addition of PAA sterilisation did not alter the transport of GLY or PG. Structural integrity was also maintained with the new banking treatments. An improved banking method can now be proposed; it can be completed in only one working day and the risk of disease transmission is reduced. PMID:15256836

  3. Novel reversible monoamine oxidase A inhibitors: highly potent and selective 3-(1H-pyrrol-3-yl)-2-oxazolidinones.

    PubMed

    Valente, Sergio; Tomassi, Stefano; Tempera, Giampiero; Saccoccio, Stefania; Agostinelli, Enzo; Mai, Antonello

    2011-12-01

    Monoamine oxidases (MAOs) are involved in various psychiatric and neurodegenerative disorders; hence, MAO inhibitors are useful agents in the therapy of Parkinson's disease, Alzheimer's dementia, and depression syndrome. Herein we report a novel series of 3-(1H-pyrrol-3-yl)-2-oxazolidinones 3-7 as reversible, highly potent and selective anti-MAO-A agents. In particular, 4b, 5b, and 4c showed a K(i-MAO-A) of 0.6, 0.8, and 1 nM, respectively, 4c being 200000-fold selective for MAO-A with respect to MAO-B. PMID:22017497

  4. TOPICAL REVIEW Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

    NASA Astrophysics Data System (ADS)

    Nagasaki, Yukio

    2010-10-01

    A poly(ethylene glycol)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol) (PEG) chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs) were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained had controlled sizes and narrow size distributions. They also showed high dispersion stability owing to the presence of PEG tethering chains on the surface. The same strategy should also be applicable to the fabrication of semiconductor quantum dots and inorganic porous nanoparticles. The preparation of nanoparticles in situ, i.e. in the presence of acetal-PEG-b-PAMA, gave the most densely packed polymer layer on the nanoparticle surface; this was not observed when coating preformed nanoparticles. PEG/polyamine block copolymer was more functional on the metal surface than PEG/polyamine graft copolymer, as confirmed by angle-dependent x-ray photoelectron spectroscopy. We successfully solubilized the C60 fullerene into aqueous media using acetal-PEG-b-PAMA. A C60/acetal-PEG-b-PAMA complex with a size below 5 nm was obtained by dialysis. The preparation and characterization of these materials are described in this review.

  5. Separation and quantitation of polyethylene glycols 400 and 3350 from human urine by high-performance liquid chromatography.

    PubMed

    Ryan, C M; Yarmush, M L; Tompkins, R G

    1992-04-01

    Polyethylene glycol 3350 (PEG 3350) is useful as an orally administered probe to measure in vivo intestinal permeability to macromolecules. Previous methods to detect polyethylene glycol (PEG) excreted in the urine have been hampered by inherent inaccuracies associated with liquid-liquid extraction and turbidimetric analysis. For accurate quantitation by previous methods, radioactive labels were required. This paper describes a method to separate and quantitate PEG 3350 and PEG 400 in human urine that is independent of radioactive labels and is accurate in clinical practice. The method uses sized regenerated cellulose membranes and mixed ion-exchange resin for sample preparation and high-performance liquid chromatography with refractive index detection for analysis. The 24-h excretion for normal individuals after an oral dose of 40 g of PEG 3350 and 5 g of PEG 400 was 0.12 +/- 0.04% of the original dose of PEG 3350 and 26.3 +/- 5.1% of the original dose of PEG 400. PMID:1501072

  6. Synthesis of highly elastic biocompatible polyurethanes based on bio-based isosorbide and poly(tetramethylene glycol) and their properties

    PubMed Central

    Kim, Hyo-Jin; Kang, Min-Sil; Knowles, Jonathan C

    2014-01-01

    Bio-based high elastic polyurethanes were prepared from hexamethylene diisocyanate and various ratios of isosorbide to poly(tetramethylene glycol) as a diol by a simple one-shot bulk polymerization without a catalyst. Successful synthesis of the polyurethanes was confirmed by Fourier transform-infrared spectroscopy and 1H nuclear magnetic resonance. Thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature was −47.8℃. The test results showed that the poly(tetramethylene glycol)/isosorbide-based elastomer exhibited not only excellent stress–strain properties but also superior resilience to the existing polyether-based polyurethane elastomers. The static and dynamic properties of the polyether/isosorbide-based thermoplastic elastomer were more suitable for dynamic applications. Moreover, such rigid diols impart biocompatible and bioactive properties to thermoplastic polyurethane elastomers. Degradation tests performed at 37℃ in phosphate buffer solution showed a mass loss of 4–9% after 8 weeks, except for the polyurethane with the lowest isosorbide content, which showed an initial rapid weight loss. These polyurethanes offer significant promise due to soft, flexible and biocompatible properties for soft tissue augmentation and regeneration. PMID:24812276

  7. Synthesis of highly elastic biocompatible polyurethanes based on bio-based isosorbide and poly(tetramethylene glycol) and their properties.

    PubMed

    Kim, Hyo-Jin; Kang, Min-Sil; Knowles, Jonathan C; Gong, Myoung-Seon

    2014-09-01

    Bio-based high elastic polyurethanes were prepared from hexamethylene diisocyanate and various ratios of isosorbide to poly(tetramethylene glycol) as a diol by a simple one-shot bulk polymerization without a catalyst. Successful synthesis of the polyurethanes was confirmed by Fourier transform-infrared spectroscopy and (1)H nuclear magnetic resonance. Thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature was -47.8℃. The test results showed that the poly(tetramethylene glycol)/isosorbide-based elastomer exhibited not only excellent stress-strain properties but also superior resilience to the existing polyether-based polyurethane elastomers. The static and dynamic properties of the polyether/isosorbide-based thermoplastic elastomer were more suitable for dynamic applications. Moreover, such rigid diols impart biocompatible and bioactive properties to thermoplastic polyurethane elastomers. Degradation tests performed at 37℃ in phosphate buffer solution showed a mass loss of 4-9% after 8 weeks, except for the polyurethane with the lowest isosorbide content, which showed an initial rapid weight loss. These polyurethanes offer significant promise due to soft, flexible and biocompatible properties for soft tissue augmentation and regeneration. PMID:24812276

  8. Highly effective poly(ethylene glycol) architectures for specific inhibition of immune receptor activation.

    PubMed

    Baird, Emily J; Holowka, David; Coates, Geoffrey W; Baird, Barbara

    2003-11-11

    Architectural features of synthetic ligands were systematically varied to optimize inhibition of mast cell degranulation initiated by multivalent crossing of IgE-receptor complexes. A series of ligands were generated by end-capping poly(ethylene glycol) (PEG) polymers and amine-based dendrimers with the hapten 2,4-dinitrophenyl (DNP). These were used to explore the influence of polymeric backbone length, valency, and hapten presentation on binding to anti-DNP IgE and inhibition of stimulated activation of RBL cells. Monovalent MPEG(5000)-DNP (IC(50) = 50 nM), bivalent DNP-PEG(3350)-DNP (IC(50) = 8 nM), bismonovalent MPEG(5000)-DNP(2) (IC(50) = 20 nM), bisbivalent DNP(2)-PEG(3350)-DNP(2) (IC(50) = 3nM) and DNP(4)-dendrimer ligands (IC(50) = 50 nM) all effectively inhibit cellular activation caused by multivalent antigen, DNP-bovine serum albumin. For different DNP ligands, we provide evidence for more effective inhibition due to (i) preferential formation of intra-IgE cross-links by bivalent ligands of sufficient length, (ii) self-association of monovalent ligands with longer tails, and (iii) higher probability of binding for bisvalent ligands. We also show that larger DNP(16)-dendrimers of higher valency trigger degranulation by cross-linking IgE-receptor complexes, whereas smaller DNP-dendrimers are inhibitory. Thus, features of synthetic ligands can be manipulated to control receptor occupation, aggregation, and inhibition of the cellular response. PMID:14596588

  9. High Resolution Structure of the ba3 Cytochrome c Oxidase from Thermus thermophilus in a Lipidic Environment

    SciTech Connect

    Tiefenbrunn, Theresa; Liu, Wei; Chen, Ying; Katritch, Vsevolod; Stout, C. David; Fee, James A.; Cherezov, Vadim

    2012-06-27

    The fundamental chemistry underpinning aerobic life on Earth involves reduction of dioxygen to water with concomitant proton translocation. This process is catalyzed by members of the heme-copper oxidase (HCO) superfamily. Despite the availability of crystal structures for all types of HCO, the mode of action for this enzyme is not understood at the atomic level, namely how vectorial H{sup +} and e{sup -} transport are coupled. Toward addressing this problem, we report wild type and A120F mutant structures of the ba{sub 3}-type cytochrome c oxidase from Thermus thermophilus at 1.8 {angstrom} resolution. The enzyme has been crystallized from the lipidic cubic phase, which mimics the biological membrane environment. The structures reveal 20 ordered lipid molecules that occupy binding sites on the protein surface or mediate crystal packing interfaces. The interior of the protein encloses 53 water molecules, including 3 trapped in the designated K-path of proton transfer and 8 in a cluster seen also in A-type enzymes that likely functions in egress of product water and proton translocation. The hydrophobic O{sub 2}-uptake channel, connecting the active site to the lipid bilayer, contains a single water molecule nearest the Cu{sub B} atom but otherwise exhibits no residual electron density. The active site contains strong electron density for a pair of bonded atoms bridging the heme Fe{sub a3} and Cu{sub B} atoms that is best modeled as peroxide. The structure of ba{sub 3}-oxidase reveals new information about the positioning of the enzyme within the membrane and the nature of its interactions with lipid molecules. The atomic resolution details provide insight into the mechanisms of electron transfer, oxygen diffusion into the active site, reduction of oxygen to water, and pumping of protons across the membrane. The development of a robust system for production of ba{sub 3}-oxidase crystals diffracting to high resolution, together with an established expression system

  10. Polyethylene Glycol 3350

    MedlinePlus

    Polyethylene glycol 3350 is used to treat occasional constipation. Polyethylene glycol 3350 is in a class of medications ... Polyethylene glycol 3350 comes as a powder to be mixed with a liquid and taken by mouth. ...

  11. High-Resolution Imaging of Polyethylene Glycol Coated Dendrimers via Combined Atomic Force and Scanning Tunneling Microscopy

    PubMed Central

    Zhong, Qian; Yin, Nai-Ning; Karsai, Arpad; da Rocha, Sandro R. P.; Liu, Gang-yu

    2015-01-01

    Dendrimers have shown great promise as drug delivery vehicles in recent years because they can be synthesized with designed size and functionalities for optimal transportation, targeting, and biocompatibility. One of the most well-known termini used for biocompatibility is polyethylene glycol (PEG), whose performance is affected by its actual conformation. However, the conformation of individual PEG bound to soft materials such as dendrimers has not been directly observed. Using atomic force microscopy (AFM) and scanning tunneling microscopy (STM), this work characterizes the structure adopted by PEGylated dendrimers with the highest resolution reported to date. AFM imaging enables visualization of the individual dendrimers, as well as the differentiation and characterization of the dendrimer core and PEG shell. STM provides direct imaging of the PEG extensions with high-resolution. Collectively, this investigation provides important insight into the structure of coated dendrimers, which is crucial for the design and development of better drug delivery vehicles. PMID:25685559

  12. Highly efficient conversion of biomass-derived glycolide to ethylene glycol over CuO in water.

    PubMed

    Xu, Lingli; Huo, Zhibao; Fu, Jun; Jin, Fangming

    2014-06-01

    The efficient conversion of biomass-derived glycolide into ethylene glycol over CuO in water was investigated. The reaction of glycolide was carried out with 25 mmol Zn and 6 mmol CuO with 25% water filling at 250 °C for 150 min, which yielded the desired ethylene glycol in 94% yield. PMID:24769741

  13. CHARACTERISTICS OF POLYPHENOL OXIDASES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO, EC 1.14.18.1 or EC 1.10.3.1) catalyzes the oxidation of o-diphenols to o-quinones. Highly reactive o-quinones couple with phenolics and specific amino acids on proteins to form the characteristic browning products in many wounded fruits, vegetables, and leaf tissues of plant...

  14. Syncephalastrum racemosum amine oxidase with high catalytic efficiency toward ethanolamine and its application in ethanolamine determination.

    PubMed

    Hirano, Yoshitaka; Chonan, Keisuke; Murayama, Kazutaka; Sakasegawa, Shin-Ich; Matsumoto, Hideyuki; Sugimori, Daisuke

    2016-05-01

    Our screening study yielded a copper amine oxidase (SrAOX) from Syncephalastrum racemosum, which showed much higher affinity and catalytic efficiency toward ethanolamine (EA) than any other amine oxidase (AOX). Following purification of the enzyme to electrophoretic homogeneity from a cell-free extract, the maximum activity toward EA was detected at pH 7.2-7.5 and 45 °C. The SrAOX complementary DNA (cDNA) was composed of a 2052-bp open reading frame encoding a 683-amino acid protein with a molecular mass of 77,162 Da. The enzyme functions as a homodimer. The deduced amino acid sequence of SrAOX showed 55.3 % identity to Rhizopus delemar AOX and contains two consensus sequences of Cu-AOX, NYDY, and HHQH, suggesting SrAOX is a type 1 Cu-AOX (i.e., a topaquinone enzyme). Structural homology modeling showed that residues (112)ML(113), (141)FADTWG(146) M158, and N318 are unique, and T144 possibly characterizes the substrate specificity of SrAOX. The recombinant enzyme (rSrAOX) was produced using Escherichia coli. Steady-state kinetic analysis of rSrAOX activity toward EA (pH 7.5 and 45 °C) gave K m and k cat values of 0.848 ± 0.009 mM and 9.11 ± 0.13 s(-1), respectively. The standard curves were linear between 0.1 and 2 mM EA, and 10 μg mL(-1)-2.5 mg mL(-1) (15 μM-3.6 mM) phosphatidylethanolamine using Streptomyces chromofuscus phospholipase D, respectively, was sufficiently sensitive for clinical use. PMID:26691518

  15. Propylene Glycol Poisoning From Excess Whiskey Ingestion

    PubMed Central

    Ku, Kevin; Sue, Gloria R.

    2015-01-01

    In this report, we describe a case of high anion gap metabolic acidosis with a significant osmolal gap attributed to the ingestion of liquor containing propylene glycol. Recently, several reports have characterized severe lactic acidosis occurring in the setting of iatrogenic unintentional overdosing of medications that use propylene glycol as a diluent, including lorazepam and diazepam. To date, no studies have explored potential effects of excess propylene glycol in the setting of alcohol intoxication. Our patient endorsed drinking large volumes of cinnamon flavored whiskey, which was likely Fireball Cinnamon Whisky. To our knowledge, this is the first case of propylene glycol toxicity from an intentional ingestion of liquor containing propylene glycol. PMID:26904700

  16. A highly sensitive biosensor for tumor maker alpha fetoprotein based on poly(ethylene glycol) doped conducting polymer PEDOT.

    PubMed

    Cui, Min; Song, Zhiling; Wu, Yumin; Guo, Bing; Fan, Xiaojian; Luo, Xiliang

    2016-05-15

    Biocompatible polymers, such as poly(ethylene glycol) (PEG), are of great significance in the development of bio-interfaces and biosensors, as they possess excellent biocompatibility and are easy for modification. A novel highly biocompatible polymer composite was synthesized herein through electrochemical polymerization of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and a PEG derivative, 4-arm PEG terminated with thiol groups. The electrodeposited conducting polymer composite of PEG doped PEDOT (PEDOT/PEG) exhibited flake-like nanostructure, large surface area and outstanding stability. In order to further immobilize antibodies, gold nanoparticles (AuNPs) were introduced to the PEDOT/PEG composite surface through their unique interaction with the thiol groups. AuNPs modified PEDOT/PEG provided a desirable support for the immobilization of various biomolecules such as antibodies for alpha fetoprotein (AFP), a vital tumor biomarker for liver cancer. The fabricated AFP biosensor demonstrated favorable selectivity, high sensitivity, and ultralow detection limit. Furthermore, owing to the presence of PEG polymers that are highly hydrophilic, such AuNPs/PEDOT/PEG based AFP biosensor also exhibited good anti-fouling ability, and it was capable of assaying target AFP in 10% (V/V) human serum samples, indicating highly feasible potential for clinical diagnosis. PMID:26774088

  17. Intermittent High Glucose Implements Stress-Induced Senescence in Human Vascular Endothelial Cells: Role of Superoxide Production by NADPH Oxidase

    PubMed Central

    Maeda, Morihiko; Hayashi, Toshio; Mizuno, Natsumi; Hattori, Yuichi; Kuzuya, Masafumi

    2015-01-01

    Impaired glucose tolerance characterized by postprandial hyperglycemia, which occurs frequently in elderly persons and represents an important preliminary step in diabetes mellitus, poses an independent risk factor for the development of atherosclerosis. Endothelial cellular senescence is reported to precede atherosclerosis. We reported that continuous high glucose stimulus causes endothelial senescence more markedly than hypertension or dyslipidemia stimulus. In the present study, we evaluated the effect of fluctuating glucose levels on human endothelial senescence. Constant high glucose increased senescence-associated-β-galactosidase(SA-β-gal) activity, a widely used marker for cellular senescence. Interestingly, in intermittent high glucose, this effect was more pronounced as well as increase of p21 and p16INK4a , senescence related proteins with DNA damage. However, telomerase was not activated and telomere length was not shortened, thus stress-induced senescence was shown. However, constant high glucose activated telomerase and shortened telomere length, which suggested replicative senescence. Intermittent but not constant high glucose strikingly up-regulated the expression of p22phox, an NADPH oxidase component, increasing superoxide. The small interfering RNA of p22phox undermined the increase in SA-β-gal activity induced by intermittent high glucose. Conclusively, intermittent high glucose can promote vascular endothelial senescence more than constant high glucose, which is in partially dependent on superoxide overproduction. PMID:25879533

  18. Mechanical, rheological, and bioactivity properties of ultra high-molecular-weight polyethylene bioactive composites containing polyethylene glycol and hydroxyapatite.

    PubMed

    Ahmad, Mazatusziha; Uzir Wahit, Mat; Abdul Kadir, Mohammed Rafiq; Mohd Dahlan, Khairul Zaman

    2012-01-01

    Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis. PMID:22666129

  19. Mechanical, Rheological, and Bioactivity Properties of Ultra High-Molecular-Weight Polyethylene Bioactive Composites Containing Polyethylene Glycol and Hydroxyapatite

    PubMed Central

    Ahmad, Mazatusziha; Wahit, Mat Uzir; Abdul Kadir, Mohammed Rafiq; Mohd Dahlan, Khairul Zaman

    2012-01-01

    Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis. PMID:22666129

  20. High longitudinal relaxivity of ultra-small gadolinium oxide prepared by microsecond laser ablation in diethylene glycol

    SciTech Connect

    Luo Ningqi; Xiao Jun; Hu Wenyong; Chen Dihu; Tian Xiumei; Yang Chuan; Li Li

    2013-04-28

    Ultra-small gadolinium oxide (Gd{sub 2}O{sub 3}) can be used as T{sub 1}-weighted Magnetic Resonance Imaging (MRI) contrast agent own to its high longitudinal relaxivity (r{sub 1}) and has attracted intensive attention in these years. In this paper, ultra-small Gd{sub 2}O{sub 3} nanoparticles of 3.8 nm in diameter have been successfully synthesized by a microsecond laser ablating a gadolinium (Gd) target in diethylene glycol (DEG). The growth inhibition effect induced by the large viscosity of DEG makes it possible to synthesize ultra-small Gd{sub 2}O{sub 3} by laser ablation in DEG. The r{sub 1} value and T{sub 1}-weighted MR images are measured by a 3.0 T MRI spectroscope. The results show these nanoparticles with a high r{sub 1} value of 9.76 s{sup -1} mM{sup -1} to be good MRI contrast agents. We propose an explanation for the high r{sub 1} value of ultra-small Gd{sub 2}O{sub 3} by considering the decreasing factor (surface to volume ratio of the nanoparticles, S/V) and the increasing factor (water hydration number of the Gd{sup 3+} on Gd{sub 2}O{sub 3} surface, q), which offer a new look into the relaxivity studies of MRI contrast agents. Our research provides a new approach to preparing ultra-small Gd{sub 2}O{sub 3} of high r{sub 1} value by laser ablation in DEG and develops the understanding of high relaxivity of ultra-small Gd{sub 2}O{sub 3} MRI contrast agents.

  1. Highly Stable PEGylated Poly(lactic-co-glycolic acid) (PLGA) Nanoparticles for the Effective Delivery of Docetaxel in Prostate Cancers

    NASA Astrophysics Data System (ADS)

    Cao, Long-Bin; Zeng, Sha; Zhao, Wei

    2016-06-01

    In the present study, a highly stable luteinizing-hormone-releasing hormone (LHRH)-conjugated PEGylated poly(lactic-co-glycolic acid) (PLGA) nanoparticles were developed for the successful treatment of prostate cancers. We have demonstrated that a unique combination of targeted drug delivery and controlled drug release is effective against prostate cancer therapy. The docetaxel (DTX)/PLGA-LHRH micelles possessed a uniform spherical shape with an average diameter of ~170 nm. The micelles exhibited a controlled drug release for up to 96 h which can minimize the non-specific systemic spread of toxic drugs during circulation while maximizing the efficiency of tumor-targeted drug delivery. The LHRH-conjugated micelles showed enhanced cellular uptake and exhibited significantly higher cytotoxicity against LNCaP cancer cells. We have showed that PLGA-LHRH induced greater caspase-3 activity indicating its superior apoptosis potential. Consistently, LHRH-conjugated micelles induced threefold and twofold higher G2/M phase arrest than compared to free DTX or PLGA NP-treated groups. Overall, results indicate that use of LHRH-conjugated nanocarriers may potentially be an effective nanocarrier to effectively treat prostate cancer.

  2. Highly Stable PEGylated Poly(lactic-co-glycolic acid) (PLGA) Nanoparticles for the Effective Delivery of Docetaxel in Prostate Cancers.

    PubMed

    Cao, Long-Bin; Zeng, Sha; Zhao, Wei

    2016-12-01

    In the present study, a highly stable luteinizing-hormone-releasing hormone (LHRH)-conjugated PEGylated poly(lactic-co-glycolic acid) (PLGA) nanoparticles were developed for the successful treatment of prostate cancers. We have demonstrated that a unique combination of targeted drug delivery and controlled drug release is effective against prostate cancer therapy. The docetaxel (DTX)/PLGA-LHRH micelles possessed a uniform spherical shape with an average diameter of ~170 nm. The micelles exhibited a controlled drug release for up to 96 h which can minimize the non-specific systemic spread of toxic drugs during circulation while maximizing the efficiency of tumor-targeted drug delivery. The LHRH-conjugated micelles showed enhanced cellular uptake and exhibited significantly higher cytotoxicity against LNCaP cancer cells. We have showed that PLGA-LHRH induced greater caspase-3 activity indicating its superior apoptosis potential. Consistently, LHRH-conjugated micelles induced threefold and twofold higher G2/M phase arrest than compared to free DTX or PLGA NP-treated groups. Overall, results indicate that use of LHRH-conjugated nanocarriers may potentially be an effective nanocarrier to effectively treat prostate cancer. PMID:27325521

  3. Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection.

    PubMed

    Cui, Jiewu; Adeloju, Samuel B; Wu, Yucheng

    2014-01-27

    A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO(x)) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA-BSA-GLA-GO(x) nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm(-2) mM(-1) for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5-6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples. PMID:24418144

  4. Efficient synthesis of high purity homo-arm and mikto-arm poly(ethylene glycol) stars using epoxide and azide-alkyne coupling chemistry.

    PubMed

    Zhang, Boyu; Zhang, Hong; Elupula, Ravinder; Alb, Alina M; Grayson, Scott M

    2014-01-01

    High purity homo-arm and mikto-arm poly(ethylene glycol) (PEG) stars are successfully prepared by the combination of epoxide ring-openings and azide-alkyne click reactions. First, monohydroxy-PEG was modified via epoxide chemistry to bear one hydroxyl and one azide functionality at the same end. An alkyne-functionalized PEG chain was then coupled to the azide. Subsequently, the remaining hydroxyl could be reactivated to an azide again and again to enable stepwise addition of alkyne-functionalized polymer arms. The use of efficient reactions for this iterative route provides star polymers with an exact number of arms, and a tailorable degree of polymerization for each arm. Detailed characterization confirms the high purity of multi-arm polyethylene glycol products. PMID:24272944

  5. Detection of glucose based on direct electron transfer reaction of glucose oxidase immobilized on highly ordered polyaniline nanotubes.

    PubMed

    Wang, Ziyi; Liu, Shuna; Wu, Ping; Cai, Chenxin

    2009-02-15

    An amperometric glucose biosensor based on the direct electron transfer of glucose oxidase (GOx) was developed by electrochemically entrapping GOx onto the inner wall of highly ordered polyaniline nanotubes (nanoPANi), which was synthesized using anodic aluminum oxide (AAO) membrane as a template. The cyclic voltammetric results indicated that GOx immobilized on the nanoPANi underwent direct electron transfer reaction, and the cyclic voltammogram displayed a pair of well-defined and nearly symmetric redox peaks with a formal potential of -405 +/- 5 mV and an apparent electron transfer rate constant of 5.8 +/- 1.6 s(-1). The biosensor had good electrocatalytic activity toward oxidation of glucose and exhibited a rapid response (approximately 3 s), a low detection limit (0.3 +/- 0.1 microM), a useful linear range (0.01-5.5 mM), high sensitivity (97.18 +/- 4.62 microA mM(-1) cm(-2)), higher biological affinity (the apparent Michaelis-Mentan constant was estimated to be 2.37 +/- 0.5 mM) as well as good stability and repeatability. In addition, the common interfering species, such as ascorbic acid, uric acid, and 4-acetamidophenol, did not cause any interference due to the use of a low detection potential (-0.3 V vs SCE). The biosensor can also be used for quantification of the concentration of glucose in real clinical samples. PMID:19170516

  6. A novel ultrasensitive phosphate amperometric nanobiosensor based on the integration of pyruvate oxidase with highly ordered gold nanowires array.

    PubMed

    Ogabiela, Edward; Adeloju, Samuel B; Cui, Jiewu; Wu, Yucheng; Chen, Wei

    2015-09-15

    A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidase (PyOx) and its cofactors, thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), with a highly ordered gold nanowires array (AuNWA) has been developed. The successful integration of PyOx and the co-factors, via crosslinking with bovine serum albumin (BSA) and glutaraldehyde (GLA), onto the AuNWA was confirmed by cyclic voltammetry and amperometry. The resulting nanobiosensor achieved a detection limit of 0.1 µM, a linear concentration range of 12.5-1000 µM, and a sensitivity of 140.3 µA mM(-1)cm(-2). Notably, the incorporation of the AuNWA reduced the required PyOx concentration by 70-120 fold and the presence of common interferants, such as chloride, sulfate, fluoride, nitrite and nitrate ions did not interfere with phosphate detection. Furthermore, the nanobiosensor demonstrated a very high stability with repeated use over two weeks and was successfully used for the determination of phosphate in water samples with an average recovery of 96.6 ± 4.9%. PMID:25913449

  7. Application of high-performance chromatographic and electrophoretic methods to the purification and characterization of glucose oxidase and catalase from Penicillium chrysogenum.

    PubMed

    Eriksson, K O; Kourteva, I; Yao, K Q; Liao, J L; Kilár, F; Hjertén, S; Chaga, G

    1987-06-26

    The high resolving power of the preparative and analytical high-performance chromatographic and electrophoretic methods recently developed in this laboratory for the separation of biopolymers has been demonstrated by the purification and characterization of glucose oxidase and catalase from Penicillium chrysogenum. Crude glucose oxidase was purified to homogeneity in one step by high-performance hydrophobic-interaction chromatography (HIC) on a pentylagarose column. Crude catalase was purified by a combination of HIC and high-performance anion-exchange chromatography on 3-diethylamino-2-hydroxypropylagarose. The homogeneity of the enzymes was monitored by high-performance electrophoresis and free zone electrophoresis. The pI values of these two enzymes determined by isoelectric focusing in the high-performance electrophoresis apparatus were 4.2 and 6.5, respectively. Their molecular weights were determined by high-performance molecular sieve chromatography on an agarose column. Glucose oxidase has a molecular weight of 175,000 and probably consists of two identical subunits, as sodium dodecyl sulphate polyacrylamide gel electrophoresis gave a molecular weight of around 72,000. The molecular weight of catalase, which is probably composed of non-identical subunits, as indicated by sodium dodecyl sulphate electrophoresis, is around 320,000. Some other characteristics of these two enzymes were also investigated, e.g., electrophoretic mobility, pH stability and optimum pH. PMID:3116021

  8. The world of DNA in glycol solution.

    PubMed

    Lindahl, Tomas

    2016-05-23

    The properties of high-molecular-weight DNA are usually investigated in neutral aqueous solutions. Strong acids and strong alkaline solutions are obviously unsuitable, as are corrosive solvents, and DNA is insoluble in most organic solvents; precipitation of DNA from aqueous solution with ethanol or isopropanol is therefore frequently used as a purification step. An exception is the organic solvent glycol (ethylene glycol, 1,2-ethanediol, dihydroxyethane, HOCH2CH2OH) and the similar solvent glycerol. Double-stranded DNA remains soluble in salt-containing glycol, although it precipitates in polyethylene glycol. (DNA also remains soluble in formamide, but the double-helical structure of DNA is much less stable in this solvent than in glycol.) However, DNA in glycol has been little investigated during the last half-century. PMID:27211487

  9. Astragaloside IV prevents damage to human mesangial cells through the inhibition of the NADPH oxidase/ROS/Akt/NF‑κB pathway under high glucose conditions.

    PubMed

    Sun, Li; Li, Weiping; Li, Weizu; Xiong, Li; Li, Guiping; Ma, Rong

    2014-07-01

    Glomerular hypertrophy and hyperfiltration are the two major pathological characteristics of the early stages of diabetic nephropathy (DN), which are respectively related to mesangial cell (MC) proliferation and a decrease in calcium influx conducted by canonical transient receptor potential cation channel 6 (TRPC6). The marked increase in the production of reactive oxygen species (ROS) induced by hyperglycemia is the main sponsor of multiple pathological pathways in DN. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is an important source of ROS production in MCs. Astragaloside IV (AS‑IV) is an active ingredient of Radix Astragali which has a potent antioxidative effect. In this study, we aimed to investigate whether high glucose (HG)‑induced NADPH oxidase activation and ROS production contribute to MC proliferation and the downregulation of TRPC6 expression; we also wished to determine the effects of AS‑IV on MCs under HG conditions. Using a human glomerular mesangial cell line, we found that treatment with AS‑IV for 48 h markedly attenuated HG‑induced proliferation and the hypertrophy of MCs in a dose‑dependent manner. The intracellular ROS level was also markedly reduced following treatment with AS‑IV. In addition, the enhanced activity of NADPH oxidase and the expression level of NADPH oxidase 4 (Nox4) protein were decreased. Treatment with AS‑IV also inhibited the phosphorylation level of Akt and IκBα in the MCs. In addition, TRPC6 protein expression and the intracellular free calcium concentration were also markedly reduced following treatment with AS‑IV under HG conditions. These results suggest that AS‑IV inhibits HG‑induced mesangial cell proliferation and glomerular contractile dysfunction through the NADPH oxidase/ROS/Akt/nuclear factor‑κB (NF‑κB) pathway, providing a new perspective for the clinical treatment of DN. PMID:24718766

  10. Facile synthesis of porous worm-like Pd nanotubes with high electrocatalytic activity and stability towards ethylene glycol oxidation.

    PubMed

    Feng, Jiu-Ju; Zhou, Dan-Ling; Xi, Huan-Xiang; Chen, Jian-Rong; Wang, Ai-Jun

    2013-08-01

    A facile method was developed for large-scale preparation of porous worm-like Pd nanotubes based on the reduction of PdO nanotubes, which were obtained by calcining the complex precipitate of [Pd(dimethylglyoxime)2]n. The Pd catalyst showed excellent electrocatalytic activity and stability towards ethylene glycol oxidation. PMID:23817778

  11. Chemical Modification with High Molecular Weight Polyethylene Glycol Reduces Transduction of Hepatocytes and Increases Efficacy of Intravenously Delivered Oncolytic Adenovirus

    PubMed Central

    Doronin, Konstantin; Shashkova, Elena V.; May, Shannon M.; Hofherr, Sean E.

    2009-01-01

    Abstract Oncolytic adenoviruses are anticancer agents that replicate within tumors and spread to uninfected tumor cells, amplifying the anticancer effect of initial transduction. We tested whether coating the viral particle with polyethylene glycol (PEG) could reduce transduction of hepatocytes and hepatotoxicity after systemic (intravenous) administration of oncolytic adenovirus serotype 5 (Ad5). Conjugating Ad5 with high molecular weight 20-kDa PEG but not with 5-kDa PEG reduced hepatocyte transduction and hepatotoxicity after intravenous injection. PEGylation with 20-kDa PEG was as efficient at detargeting adenovirus from Kupffer cells and hepatocytes as virus predosing and warfarin. Bioluminescence imaging of virus distribution in two xenograft tumor models in nude mice demonstrated that PEGylation with 20-kDa PEG reduced liver infection 19- to 90-fold. Tumor transduction levels were similar for vectors PEGylated with 20-kDa PEG and unPEGylated vectors. Anticancer efficacy after a single intravenous injection was retained at the level of unmodified vector in large established prostate carcinoma xenografts, resulting in complete elimination of tumors in all animals and long-term tumor-free survival. Anticancer efficacy after a single intravenous injection was increased in large established hepatocellular carcinoma xenografts, resulting in significant prolongation of survival as compared with unmodified vector. The increase in efficacy was comparable to that obtained with predosing and warfarin pretreatment, significantly extending the median of survival. Shielding adenovirus with 20-kDa PEG may be a useful approach to improve the therapeutic window of oncolytic adenovirus after systemic delivery to primary and metastatic tumor sites. PMID:19469693

  12. NADPH oxidase is implicated in the pathogenesis of oxidative phosphorylation dysfunction in mice fed a high-fat diet.

    PubMed

    García-Ruiz, Inmaculada; Solís-Muñoz, Pablo; Fernández-Moreira, Daniel; Grau, Montserrat; Muñoz-Yagüe, Teresa; Solís-Herruzo, José A

    2016-01-01

    The aim of this study was to evaluate the role of NADPH oxidase (NADPHox) in the pathogenesis of oxidative phosphorylation (OXPHOS) dysfunction as found in mice fed a high-fat diet (HFD). C57BL/6J mice were distributed in four groups: WT/SCD: six wild-type (WT) mice fed a standard chow diet (SCD); WT/HFD, six WT mice fed a HFD; NOX2(-/-)/SCD, six NADPHox-deficient mice on a SCD; (4) NOX2(-/-)/HFD, six NADPHox-deficient mice on a HFD. After 32 weeks, we studied the liver for: histology; OXPHOS complex activity; fully assembled OXPHOS complexes and their subunits; gene expression of OXPHOS subunits; oxidative and nitrosative stress; and oxidative DNA damage. In the liver of WT/HFD mice, we found a significant decreased in the activity of all OXPHOS complexes, in fully assembled complexes, in the amount of OXPHOS subunits, and in gene expression of mitochondrial DNA-encoded subunits. 8-hydroxy-2'-deoxyguanosine was only increased in mitochondrial DNA. The liver of NOX(-/-)/HFD mice showed mild steatosis but no non-alcoholic steatohepatitis (NASH) lesions were found. OXPHOS activity, OXPHOS subunits, and assembly of subunits into OXPHOS complexes were normal in these mice. We conclude that this study shows that NADPH deficiency protects mice from developing OXPHOS dysfunction and NASH caused by a HFD. PMID:27173483

  13. NADPH oxidase is implicated in the pathogenesis of oxidative phosphorylation dysfunction in mice fed a high-fat diet

    PubMed Central

    García-Ruiz, Inmaculada; Solís-Muñoz, Pablo; Fernández-Moreira, Daniel; Grau, Montserrat; Muñoz-Yagüe, Teresa; Solís-Herruzo, José A.

    2016-01-01

    The aim of this study was to evaluate the role of NADPH oxidase (NADPHox) in the pathogenesis of oxidative phosphorylation (OXPHOS) dysfunction as found in mice fed a high-fat diet (HFD). C57BL/6J mice were distributed in four groups: WT/SCD: six wild-type (WT) mice fed a standard chow diet (SCD); WT/HFD, six WT mice fed a HFD; NOX2−/−/SCD, six NADPHox-deficient mice on a SCD; (4) NOX2−/−/HFD, six NADPHox-deficient mice on a HFD. After 32 weeks, we studied the liver for: histology; OXPHOS complex activity; fully assembled OXPHOS complexes and their subunits; gene expression of OXPHOS subunits; oxidative and nitrosative stress; and oxidative DNA damage. In the liver of WT/HFD mice, we found a significant decreased in the activity of all OXPHOS complexes, in fully assembled complexes, in the amount of OXPHOS subunits, and in gene expression of mitochondrial DNA-encoded subunits. 8-hydroxy-2′-deoxyguanosine was only increased in mitochondrial DNA. The liver of NOX−/−/HFD mice showed mild steatosis but no non-alcoholic steatohepatitis (NASH) lesions were found. OXPHOS activity, OXPHOS subunits, and assembly of subunits into OXPHOS complexes were normal in these mice. We conclude that this study shows that NADPH deficiency protects mice from developing OXPHOS dysfunction and NASH caused by a HFD. PMID:27173483

  14. A review of the nonclinical safety of Transcutol®, a highly purified form of diethylene glycol monoethyl ether (DEGEE) used as a pharmaceutical excipient.

    PubMed

    Sullivan, Dexter W; Gad, Shayne C; Julien, Marjorie

    2014-10-01

    Transcutol® (Diethylene glycol monoethyl ether, DEGEE), CAS # 111-90-0, is commonly used as a vehicle in the formulation or manufacturing process of pharmaceuticals, cosmetics, and food additives. This paper presents unpublished nonclinical safety data using a form of DEGEE which includes a significantly decreased level of impurities, specifically ethylene glycol and diethylene glycol. It also reviews the history of use, regulatory status, and previously published toxicity data for DEGEE. The review supports that DEGEE is well tolerated across animal species and gender with toxicity occurring only at levels well above those intended for human use. At high levels of exposure, the kidney is identified as the critical target organ of DEGEE toxicity. DEGEE is negative for genotoxicity in in vitro and in vivo studies. Subchronic and chronic toxicity studies produced no reports of preneoplastic changes in organs, but the animal data is insufficient to allow a definitive opinion as to carcinogenicity. In silico data suggested that DEGEE is not carcinogenic or genotoxic. Developmental toxicity was seen in rats but only at levels 200 times greater than the estimated oral Permissible Daily Exposure Level of 10 mg/kg/day. The nonclinical data along with the long history of DEGEE use as a vehicle and solvent by multiple routes provide evidence of its safety. Furthermore, the novel data discussed herein provides evidence that toxicity previously associated with high levels of DEGEE in nonclinical studies conducted prior to 1990 could possibly be attributed to the presence of significant amounts of ethylene glycol or other impurities. PMID:25016034

  15. High mass clearance of autoantibodies from a murine model of lupus nephritis by immunoadsorption using star-configured polyethylene glycols.

    PubMed

    Ross, E A; Branham, M L; Tebbett, I R

    2001-04-01

    The extracorporeal immunoadsorption of antibodies as part of the therapy for human autoimmune diseases has been limited by technology with inadequate and nonselective mass clearance or problems with bioincompatibility. To overcome these shortcomings, we designed a method utilizing star-configured polyethylene glycols (star-PEGs) having up to 63 free arms with immunoreactive (tresylate ester) end-groups for each arm immobilized to a polymer support substrate. The flexibility and length of the arms are thought to allow optimization of epitope presentation and to permit interaction with immunoligands on adjacent arms. To demonstrate efficacy we used an in vitro murine antibody model of human lupus nephritis, wherein we could study the kinetics and mass clearance of hybridoma derived antihistone antibodies from human plasma. Histones were covalently bound to the star-PEG end-groups and the kinetics of antibody adsorption were assessed using a surface plasmon resonance technique. The equilibrium constants of antihistone antibody binding to histone-star-PEGs that were linked to a support grid demonstrated high affinity with a KA of 3.56E + 07 and a KD of 2.81E - 08. The optimum reaction conditions were determined to accomplish the hydrophilization of polysulfone (PS; by an aqueous nitration method) and polymethylmethacrylate substrates (PMMA; by hydrazine), using sheet casts of both polymer substances. Hollow fiber devices of these polymers (commercial hemodialyzers) were modified so that histone-bound star-PEGs were linked to their intracapillary luminal surfaces, using a process which we have shown retains their immunoadsorption properties for antihistone antibodies. A closed loop recirculating model was constructed to measure mass clearance of antibodies from a reservoir. After optimizing conditions using extraction from saline solutions, the removal of antibody from human plasma by control and surface-modified devices was assessed over 4 h. There was no measurable

  16. Facile synthesis of porous worm-like Pd nanotubes with high electrocatalytic activity and stability towards ethylene glycol oxidation

    NASA Astrophysics Data System (ADS)

    Feng, Jiu-Ju; Zhou, Dan-Ling; Xi, Huan-Xiang; Chen, Jian-Rong; Wang, Ai-Jun

    2013-07-01

    A facile method was developed for large-scale preparation of porous worm-like Pd nanotubes based on the reduction of PdO nanotubes, which were obtained by calcining the complex precipitate of [Pd(dimethylglyoxime)2]n. The Pd catalyst showed excellent electrocatalytic activity and stability towards ethylene glycol oxidation.A facile method was developed for large-scale preparation of porous worm-like Pd nanotubes based on the reduction of PdO nanotubes, which were obtained by calcining the complex precipitate of [Pd(dimethylglyoxime)2]n. The Pd catalyst showed excellent electrocatalytic activity and stability towards ethylene glycol oxidation. Electronic supplementary information (ESI) available: Experimental section and Fig. S1-S7. See DOI: 10.1039/c3nr01578e

  17. MicroRNA-146a decreases high glucose/thrombin-induced endothelial inflammation by inhibiting NAPDH oxidase 4 expression.

    PubMed

    Wang, Huang-Joe; Huang, Yuan-Li; Shih, Ya-Yun; Wu, Hsing-Yu; Peng, Ching-Tien; Lo, Wan-Yu

    2014-01-01

    Diabetes is associated with hyperglycemia and increased thrombin production. However, it is unknown whether a combination of high glucose and thrombin can modulate the expression of NAPDH oxidase (Nox) subtypes in human aortic endothelial cells (HAECs). Moreover, we investigated the role of a diabetes-associated microRNA (miR-146a) in a diabetic atherothrombosis model. We showed that high glucose (HG) exerted a synergistic effect with thrombin to induce a 10.69-fold increase in Nox4 mRNA level in HAECs. Increased Nox4 mRNA expression was associated with increased Nox4 protein expression and ROS production. Inflammatory cytokine kit identified that the treatment increased IL-8 and IL-6 levels. Moreover, HG/thrombin treatment caused an 11.43-fold increase of THP-1 adhesion to HAECs. In silico analysis identified the homology between miR-146a and the 3'-untranslated region of the Nox4 mRNA, and a luciferase reporter assay confirmed that the miR-146a mimic bound to this Nox4 regulatory region. Additionally, miR-146a expression was decreased to 58% of that in the control, indicating impaired feedback restraint of HG/thrombin-induced endothelial inflammation. In contrast, miR-146a mimic transfection attenuated HG/thrombin-induced upregulation of Nox4 expression, ROS generation, and inflammatory phenotypes. In conclusion, miR-146a is involved in the regulation of endothelial inflammation via modulation of Nox4 expression in a diabetic atherothrombosis model. PMID:25298619

  18. Development of post-column enzymic reactors with immobilized alcohol oxidase for use in the high-performance liquid chromatographic assay of alcohols with electrochemical detection.

    PubMed

    Tagliaro, F; Schiavon, G; Dorizzi, R; Marigo, M

    1991-01-18

    The development of a very sensitive, direct injection high-performance liquid chromatographic method, using a post-column reactor with immobilized alcohol oxidase, was undertaken with the aim of determining methanol and ethanol levels in microlitre volumes of biological samples. After reversed-phase chromatography to separate methanol and ethanol, the analytes were enzymically converted into the respective aldehydes with formation of stoichiometric amounts of hydrogen peroxide, which could be measured via electrochemical oxidation at a platinum electrode. Some problems were encountered in the development of solid-phase enzymic reactors, using a delicate enzyme, that is prone to lose activity, such as alcohol oxidase. Owing to the slightly alkaline pH required for the optimum activity of alcohol oxidase, polymeric columns seemed to be preferable for the chromatography. HEMA copolymer was chosen as the stationary phase, but the methanol and ethanol peaks eluted close together and posed severe problems of limiting post-column band spreading. Reactors based on coarse supports for enzyme immobilization gave unacceptable band spreading, causing the methanol and ethanol peaks to overlap. On the other hand high-performance liquid chromatographic packings maintained the efficiency of the chromatographic separation, quite independently of the reactor volume. Polymeric supports proved superior to silicas in maintaining the enzyme activity. However, relevant changes in the enzyme substrate specificity were observed after immobilization. PMID:2061376

  19. Thioredoxin-interacting protein mediates high glucose-induced reactive oxygen species generation by mitochondria and the NADPH oxidase, Nox4, in mesangial cells.

    PubMed

    Shah, Anu; Xia, Ling; Goldberg, Howard; Lee, Ken W; Quaggin, Susan E; Fantus, I George

    2013-03-01

    Thioredoxin-interacting protein (TxNIP) is up-regulated by high glucose and is associated with oxidative stress. It has been implicated in hyperglycemia-induced β-cell dysfunction and apoptosis. As high glucose and oxidative stress mediate diabetic nephropathy (DN), the contribution of TxNIP was investigated in renal mesangial cell reactive oxygen species (ROS) generation and collagen synthesis. To determine the role of TxNIP, mouse mesangial cells (MC) cultured from wild-type C3H and TxNIP-deficient Hcb-19 mice were incubated in HG. Confocal microscopy was used to measure total and mitochondrial ROS production (DCF and MitoSOX) and collagen IV. Trx and NADPH oxidase activities were assayed and NADPH oxidase isoforms, Nox2 and Nox4, and antioxidant enzymes were determined by immunoblotting. C3H MC exposed to HG elicited a significant increase in cellular and mitochondrial ROS as well as Nox4 protein expression and NADPH oxidase activation, whereas Hcb-19 MC showed no response. Trx activity was attenuated by HG only in C3H MC. These defects in Hcb-19 MC were not due to increased antioxidant enzymes or scavenging of ROS, but associated with decreased ROS generation. Adenovirus-mediated overexpression of TxNIP in Hcb-19 MC and TxNIP knockdown with siRNA in C3H confirmed the specific role of TxNIP. Collagen IV accumulation in HG was markedly reduced in Hcb-19 cells. TxNIP is a critical component of the HG-ROS signaling pathway, required for the induction of mitochondrial and total cell ROS and the NADPH oxidase isoform, Nox4. TxNIP is a potential target to prevent DN. PMID:23329835

  20. Thioredoxin-interacting Protein Mediates High Glucose-induced Reactive Oxygen Species Generation by Mitochondria and the NADPH Oxidase, Nox4, in Mesangial Cells*

    PubMed Central

    Shah, Anu; Xia, Ling; Goldberg, Howard; Lee, Ken W.; Quaggin, Susan E.; Fantus, I. George

    2013-01-01

    Thioredoxin-interacting protein (TxNIP) is up-regulated by high glucose and is associated with oxidative stress. It has been implicated in hyperglycemia-induced β-cell dysfunction and apoptosis. As high glucose and oxidative stress mediate diabetic nephropathy (DN), the contribution of TxNIP was investigated in renal mesangial cell reactive oxygen species (ROS) generation and collagen synthesis. To determine the role of TxNIP, mouse mesangial cells (MC) cultured from wild-type C3H and TxNIP-deficient Hcb-19 mice were incubated in HG. Confocal microscopy was used to measure total and mitochondrial ROS production (DCF and MitoSOX) and collagen IV. Trx and NADPH oxidase activities were assayed and NADPH oxidase isoforms, Nox2 and Nox4, and antioxidant enzymes were determined by immunoblotting. C3H MC exposed to HG elicited a significant increase in cellular and mitochondrial ROS as well as Nox4 protein expression and NADPH oxidase activation, whereas Hcb-19 MC showed no response. Trx activity was attenuated by HG only in C3H MC. These defects in Hcb-19 MC were not due to increased antioxidant enzymes or scavenging of ROS, but associated with decreased ROS generation. Adenovirus-mediated overexpression of TxNIP in Hcb-19 MC and TxNIP knockdown with siRNA in C3H confirmed the specific role of TxNIP. Collagen IV accumulation in HG was markedly reduced in Hcb-19 cells. TxNIP is a critical component of the HG-ROS signaling pathway, required for the induction of mitochondrial and total cell ROS and the NADPH oxidase isoform, Nox4. TxNIP is a potential target to prevent DN. PMID:23329835

  1. Two tyrosyl radicals stabilize high oxidation states in cytochrome c oxidase for efficient energy conservation and proton translocation

    NASA Astrophysics Data System (ADS)

    Rousseau, Denis

    2012-02-01

    The reaction of hydrogen peroxide (H2O2) with oxidized bovine cytochrome c oxidase (bCcO) was studied by electron paramagnetic resonance (EPR) to determine the properties of radical intermediates. Two distinct radicals with widths of 12 and 46 G are directly observed by X-band CW-EPR in the reaction of bCcO with H2O2 at pH 6 and pH 8. High-frequency EPR (D-band) provides assignments to tyrosine for both radicals based on well-resolved g-tensors. The 46 G wide radical has extensive hyperfine structure and can be fit with parameters consistent with Y129. However, the 12 G wide radical has minimal hyperfine structure and can be fit using parameters unique to the post-translationally modified Y244 in CcO. The results are supported by mixed quantum mechanics and molecular mechanics calculations. This study reports spectroscopic evidence of a radical formed on the modified tyrosine in CcO and resolves the much debated controversy of whether the wide radical seen at low pH in the bovine system is a tyrosine or tryptophan. A model is presented showing how radical formation and migration may play an essential role in proton translocation. This work was done in collaboration with Michelle A. Yu, Tsuyoshi Egawa, Syun-Ru Yeh and Gary J. Gerfen from Albert Einstein College of Medicine; Kyoko Shinzawa-Itoh and Shinya Yoshikawa from the University of Hyogo; and Victor Guallar from the Barcelona Supercomputing Center.

  2. Azure B, a metabolite of methylene blue, is a high-potency, reversible inhibitor of monoamine oxidase

    SciTech Connect

    Petzer, Anél; Harvey, Brian H.; Wegener, Gregers; Petzer, Jacobus P.

    2012-02-01

    Methylene blue (MB) has been shown to act at multiple cellular and molecular targets and as a result possesses diverse medical applications. Among these is a high potency reversible inhibition of monoamine oxidase A (MAO-A) that may, at least in part, underlie its adverse effects but also its psycho- and neuromodulatory actions. MB is metabolized to yield N-demethylated products of which azure B, the monodemethyl species, is the major metabolite. Similar to MB, azure B also displays a variety of biological activities and may therefore contribute to the pharmacological profile of MB. Based on these observations, the present study examines the interactions of azure B with recombinant human MAO-A and -B. The results show that azure B is a potent MAO-A inhibitor (IC{sub 50} = 11 nM), approximately 6-fold more potent than is MB (IC{sub 50} = 70 nM) under identical conditions. Measurements of the time-dependency of inhibition suggest that the interaction of azure B with MAO-A is reversible. Azure B also reversibly inhibits the MAO-B isozyme with an IC{sub 50} value of 968 nM. These results suggest that azure B may be a hitherto under recognized contributor to the pharmacology and toxicology of MB by blocking central and peripheral MAO-A activity and as such needs to be considered during its use in humans and animals. Highlights: ► Methylene blue (MB) is a known potent MAO-A inhibitor. ► Azure B, the major metabolite of MB, is more potent as a MAO-A inhibitor. ► Azure B may be a contributor to the CNS pharmacology and toxicology of MB.

  3. The furofuran-ring selectivity, hydrogen peroxide-production and low Km value are the three elements for highly effective detoxification of aflatoxin oxidase.

    PubMed

    Wu, Yuan-Zhen; Lu, Fu-Pu; Jiang, Hai-Lan; Tan, Cui-Ping; Yao, Dong-Sheng; Xie, Chun-Fang; Liu, Da-Ling

    2015-02-01

    AFO (aflatoxin oxidase), an enzyme from Armillariella tabescens previously named aflatoxin detoxifizyme, exhibits oxidative detoxification activity toward aflatoxin B1 and sterigmatocystin. Bioinformatics reveals that AFO is a newly discovered oxidase because AFO does not share any significant similarities with any known oxidase. It is critically important to understand how AFO acts on aflatoxin B1. In this study, in addition to aflatoxin B1 (AFB1) and sterigmatocystin (ST), five other chemicals that have furan or pyran structures were investigated. The results indicated that in addition to AFB1 and ST, AFO is also able to act on versicolorin A, 3,4-dihydro-2H-pyran and furan. These results suggested that 8,9-unsaturated carboncarbon bond of aflatoxin B1 is the potential reactive site for AFO. Further findings indicated that the action of AFO is oxygen-dependent and hydrogen peroxide-producing. The simultaneously produced-hydrogen peroxide possibly plays the essential role in detoxification of AFO. In addition, the extremely low Km value of 0.33 µmol/l for AFO-AFB1 and 0.11 µmol/l for AFO-ST signifies that AFO is highly selective for AFB1 as well as ST. PMID:25533793

  4. Intraperitoneal administration of high doses of polyethylene glycol (PEG) causes hepatic subcapsular necrosis and low-grade peritonitis with a rise in hepatic biomarkers.

    PubMed

    Pellegrini, Giovanni; Starkey Lewis, Phil J; Palmer, Luke; Hetzel, Udo; Goldring, Christopher E; Park, B Kevin; Kipar, Anja; Williams, Dominic P

    2013-12-15

    Polyethylene glycols (PEGs) are commonly employed as excipients in preclinical studies and in vitro experiments to dissolve poorly hydrosoluble drugs. Their use is generally considered safe in both animals and humans; however, limited data is available concerning the safety of PEGs when administered parenterally. The results of our investigation demonstrate that PEG-400 can have an irritant effect on serosal surfaces and causes subcapsular hepatocellular necrosis in mice when administered intraperitoneally at a high dose (4 mL/kg). Accordingly, levels of serum biomarkers of liver injury need to be carefully interpreted in studies where PEG is administered intraperitoneally and always in association with the results of the histological assessment. PMID:23831209

  5. Protoporphyrinogen oxidase: high affinity tetrahydrophthalimide radioligand for the inhibitor/herbicide-binding site in mouse liver mitochondria.

    PubMed

    Birchfield, N B; Casida, J E

    1996-01-01

    Protoporphyrinogen oxidase (protox), the last common enzyme in heme and chlorophyll biosynthesis, is the target of several classes of herbicides acting as inhibitors in both plants and mammals. N-(4-Chloro-2-fluoro-5-(propargyloxy)phenyl)-3,4,5,6-tetrahydro phthalimide (a potent protox inhibitor referred to as THP) was synthesized as a candidate radioligand ([3H]-THP) by selective catalytic reduction of 3,6-dihydrophthalic anhydride (DHPA) with tritium gas followed by condensation in 45% yield with 4-chloro-2-fluoro-5-(propargyloxy)aniline. Insertion of tritium at the 3 and 6 carbons of DHPA as well as the expected 4 and 5 carbons resulted in high specific activity [3H]THP (92 Ci/mmol). This radioligand undergoes rapid, specific, saturable, and reversible binding to the inhibitor/herbicide binding site of the protox component of cholate-solubilized mouse liver mitochondria with an apparent Kd of 0.41 nM and Bmax of 0.40 pmol/mg of protein. In the standard assay, mouse preparation (150 micrograms of protein) and [3H]THP (0.5 nM) are incubated in 500 microL of phosphate buffer at pH 7.2 for 15 min at 25 degrees C followed by addition of ammonium sulfate and filtration with glass fiber filters. The potencies of five nitrodiphenyl ethers and two other herbicides as inhibitors of [3H]THP binding correlate well with those for inhibition of protox activity (r2 = 0.97, n = 7), thus validating the binding assay as relevant to enzyme inhibition. It is also suitable to determine in vivo block as illustrated by an approximately 50% decrease in [3H]THP binding in liver mitochondria from mice treated ip with oxyfluorfen at 4 mg/kg. This is the first report of a binding assay for protox in mammals. The high affinity and specific activity of [3H]THP facilitate quantitation of protox and therefore research on a sensitive inhibition site for porphyrin biosynthesis. PMID:8902268

  6. High carbon dioxide solubilities in imidazolium-based ionic liquids and in poly(ethylene glycol) dimethyl ether.

    PubMed

    Revelli, Anne-Laure; Mutelet, Fabrice; Jaubert, Jean-Noël

    2010-10-14

    This work is focused on the possible capture of carbon dioxide using ionic liquids (ILs). Such solvents are gaining special attention because the efficiency of many processes can be enhanced by the judicious manipulation of their properties. The absorption of greenhouse gases can be enhanced by the basic character of the IL. In this work, these characteristics are evaluated through the study of the gas-liquid equilibrium of four imidazolium-based ILs: 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF(4)], 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN], 1,3-dimethylimidazolium methylphosphonate [DMIM][MP], and 1,3-diethoxyimidazolium bis(trifluoromethylsulfonyl)imide [(ETO)(2)IM][Tf(2)N] with CO(2) at temperatures up to 373 K and pressures up to 300 bar. Solubility of carbon dioxide in poly(ethylene glycol) dimethyl ether, component of selexol, was also measured to evaluate the capture's efficiency of ionic liquids. Experimental data indicate that 67 to 123 g of CO(2) can be absorbed per kg of ionic liquid and 198 g per kg of poly(ethylene glycol) dimethyl ether. PMID:20853857

  7. [Isolation and characteristics of micromycetes--producers of neutral phenol oxidase from trophic soil with a high level of dioxins].

    PubMed

    Vasil'chenko, L G; Koroleva, O V; Stepanova, E V; Landesman, E O; Rabinovich, M L

    2000-01-01

    Samples of South Vietnamese soils intensely treated with Agent Orange defoliant were tested for the presence of fungi and actinomycetes with elevated phenol oxidase activity. As a result, fast-growing non-sporulating strain producing neutral phenol oxidases was isolated and identified as Mycelia sterilia INBI 2-26. The strain formed extracellular phenol oxidases during surface growth on liquid medium in the presence of guayacol and copper sulfate, as well as during submerged cultivation in liquid medium containing wheat bran and sugar beet pulp. Isoelectric focusing of cultural liquid has revealed two major catechol oxidases (PO1 and PO2) with pI 3.5 and 8, respectively. The enzymes were purified by ultrafiltration, ion exchange chromatography and exclusion HPLC. Both were stable between pH 3 and 8. At pH 8 and 40 degrees C they retained at least 50% of activity after incubation for 50 h. At 50 degrees C PO2 was more stable and retained 40% of activity after 50 h, whereas PO1 was inactivated in 3-6 h. The pH optimums for PO1 and PO2 towards catechol were equal to 6 and 6.5, and the Km values were 1.5 +/- 0.35 and 1.25 +/- 0.2 mM, respectively. PO1 and PO2 most optimally oxidized 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) at pH 3 with Km values 1.6 +/- 0.18 and 0.045 +/- 0.01 mM, respectively, but displayed no activity towards tyrosine. The PO2 absorbance spectrum had a peak at 600 nm, thus indicating the enzyme to be a member of the laccase family. PMID:10994189

  8. Poly(Ethylene Glycol) as a Scaffold for High-Affinity Open-Channel Blockers of the Mouse Nicotinic Acetylcholine Receptor

    PubMed Central

    Lin, Wan-Chen; Licht, Stuart

    2014-01-01

    High-affinity blockers for an ion channel often have complex molecular structures that are synthetically challenging and/or laborious. Here we show that high-affinity blockers for the mouse nicotinic acetylcholine receptor (AChR) can be prepared from a structurally simple material, poly(ethylene glycol) (PEG). The PEG-based blockers (PQ1–5), comprised of a flexible octa(ethylene glycol) scaffold and two terminal quaternary ammonium groups, exert low- to sub-micromolar affinities for the open AChR pore (measured via single-channel analysis of AChRs expressed in human embryonic kidney cells). PQ1–5 are comparable in pore-binding affinity to the strongest AChR open-channel blockers previously reported, which have complex molecular structures. These results suggest a general approach for designing potent open-channel blockers from a structurally flexible polymer. This design strategy involves simple synthetic procedures and does not require detailed information about the structure of an ion-channel pore. PMID:25386750

  9. Toxicity of ethylene glycol, diethylene glycol, and propylene glycol to human cells in culture

    SciTech Connect

    Mochida, K.; Gomyoda, M.

    1987-01-01

    Tissue culture toxicity of various alcohols has been reported by Dillingham who used mouse L cells and Koerker who used mouse neuroblastoma cells. The toxicity of various polyhydric alcohols (ethylene glycol, diethylene glycol and propylene glycol) has apparently not been determined, under conditions of culture. The authors report the toxicity of ethylene glycol, diethylene glycol and propylene glycol and KB cells and the results are compared with previous data obtained using their cell culture system.

  10. Genotoxicity of glycol ethers.

    PubMed Central

    McGregor, D B

    1984-01-01

    The genetic toxicology of glycol ethers is reviewed. Ethylene glycol monomethyl ether (EGME) and diglyme have been more extensively studied than other members of this series. Most results indicate a lack of genotoxic potential, but certain tests have yielded positive responses with certain compounds. Ethylene glycol monoethyl ether (EGEE) induced sister chromatid exchanges and chromosomal aberrations in cultured cells. Both EGME and diglyme induced mouse sperm head morphological changes, male rat weak dominant lethal mutations and marked, but reversible, loss of male rat fertility. PMID:6541999

  11. Certain glycol ethers eliminated from toxic chemical release reporting requirements

    SciTech Connect

    1994-09-01

    Effective June 28, 1994, the U.S. Environmental Protection Agency (EPA) eliminated high molecular weight glycol ethers from the reporting requirements of section 313 of the Emergency Planning and Community Right-To-Know Act of 1986 (EPCRA). EPCRA (42 U.S.C. 11023) is also referred to as Title III of the Superfund Amendments and Reauthorization Act (SARA) of 1986. EPA redefined the glycol ethers category list of chemicals subject to reporting based on an EPA review of available human health data on short-chain glycol ethers. EPA is removing only the surfactant glycol ethers, which are high molecular weight glycol ethers, i.e., those with pendant alkyl groups and that typically have eight or more carbon atoms. The redefinition retains certain glycol ethers (i.e., ethylene glycol ethers where there are 1,2, or 3 repeating ethylene oxide groups) in the category. These are reasonably anticipated to cause adverse human health effects.

  12. Ruminal fermentation of propylene glycol and glycerol.

    PubMed

    Trabue, Steven; Scoggin, Kenwood; Tjandrakusuma, Siska; Rasmussen, Mark A; Reilly, Peter J

    2007-08-22

    Bovine rumen fluid was fermented anaerobically with 25 mM R-propylene glycol, S-propylene glycol, or glycerol added. After 24 h, all of the propylene glycol enantiomers and approximately 80% of the glycerol were metabolized. Acetate, propionate, butyrate, valerate, and caproate concentrations, in decreasing order, all increased with incubation time. Addition of any of the three substrates somewhat decreased acetate formation, while addition of either propylene glycol increased propionate formation but decreased that of butyrate. R- and S-propylene glycol did not differ significantly in either their rates of disappearance or the products formed when they were added to the fermentation medium. Fermentations of rumen fluid containing propylene glycol emitted the sulfur-containing gases 1-propanethiol, 1-(methylthio)propane, methylthiirane, 2,4-dimethylthiophene, 1-(methylthio)-1-propanethiol, dipropyl disulfide, 1-(propylthio)-1-propanethiol, dipropyl trisulfide, 3,5-diethyl-1,2,4-trithiolane, 2-ethyl-1,3-dithiane, and 2,4,6-triethyl-1,3,5-trithiane. Metabolic pathways that yield each of these gases are proposed. The sulfur-containing gases produced during propylene glycol fermentation in the rumen may contribute to the toxic effects seen in cattle when high doses are administered for therapeutic purposes. PMID:17655323

  13. Ethylene glycol poisoning

    MedlinePlus

    ... attempt or as a substitute for drinking alcohol (ethanol). This article is for information only. Do NOT ... attempt or as a substitute for drinking alcohol (ethanol). Ethylene glycol is found in many household products, ...

  14. High-speed separation of proteins by microchip electrophoresis using a polyethylene glycol-coated plastic chip with a sodium dodecyl sulfate-linear polyacrylamide solution.

    PubMed

    Nagata, Hideya; Tabuchi, Mari; Hirano, Ken; Baba, Yoshinobu

    2005-07-01

    In this paper, we describe a method for size-based electrophoretic separation of sodium dodecyl sulfate (SDS)-protein complexes on a polymethyl methacrylate (PMMA) microchip, using a separation buffer solution containing SDS and linear polyacrylamide as a sieving matrix. We developed optimum conditions under which protein separations can be performed, using polyethylene glycol (PEG)-coated polymer microchips and electrokinetic sample injection. We studied the performance of protein separations on the PEG-coated PMMA microchip. The electrophoretic separation of proteins (21.5-116.0 kDa) was completed with separation lengths of 3 mm, achieved within 8 s on the PEG-coated microchip. This high-speed method may be applied to protein separations over a large range of molecular weight, making the PEG-coated microchip approach applicable to high-speed proteome analysis systems. PMID:15937980

  15. Highly sensitive luminol electrochemiluminescence immunosensor based on ZnO nanoparticles and glucose oxidase decorated graphene for cancer biomarker detection.

    PubMed

    Cheng, Yinfeng; Yuan, Ruo; Chai, Yaqin; Niu, Huan; Cao, Yaling; Liu, Huijing; Bai, Lijuan; Yuan, Yali

    2012-10-01

    In this work, we reported a sandwiched luminol electrochemiluminescence (ECL) immunosensor using ZnO nanoparticles (ZnONPs) and glucose oxidase (GOD) decorated graphene as labels and in situ generated hydrogen peroxide as coreactant. In order to construct the base of the immunosensor, a hybrid architecture of Au nanoparticles and graphene by reduction of HAuCl(4) and graphene oxide (GO) with ascorbic acid was prepared. The resulted hybrid architecture modified electrode provided an excellent platform for immobilization of antibody with good bioactivity and stability. Then, ZnONPs and GOD functionalized graphene labeled secondary antibody was designed for fabricating a novel sandwiched ECL immunosensor. Enhanced sensitivity was obtained by in situ generating hydrogen peroxide with glucose oxidase and the catalysis of ZnONPs to the ECL reaction of luminol-H(2)O(2) system. The as-prepared ECL immunosensor exhibited excellent analytical property for the detection of carcinoembryonic antigen (CEA) in the range from 10 pg mL(-1) to 80 ng mL(-1) and with a detection limit of 3.3 pg mL(-1) (SN(-1)=3). The amplification strategy performed good promise for clinical application of screening of cancer biomarkers. PMID:22938618

  16. Realizing Highly Efficient Inverted Photovoltaic Cells by Combination of Nonconjugated Small-Molecule Zwitterions with Polyethylene Glycol.

    PubMed

    Zhang, Wenjun; Song, Changjian; Liu, Xiaohui; Fang, Junfeng

    2016-07-20

    Organic ionic materials have been reported to be efficient cathode interlayer (CIL) materials in polymer solar cells (PSCs); however, most of them are employed in conventional PSCs. For an inverted structural device which has better stability, the efficiency is still far from expectation and the report is also limited. In this study, by using nonconjugated zwitterions as the CIL and inverted structure, the power conversion efficiency (PCE) is ∼6%, though the PCE can reach 9.14% in the conventional device. By introducing polyethylene glycol (PEG) into the zwitterions, the PCE of the inverted PSCs was improved ∼33% and reached ∼8% mainly because of the enhancement of the open-circuit voltage (Voc) and fill factor (FF). Further research on the device parameters, work functions, morphology of indium tin oxide (ITO) with various CILs, and recombination resistance of the devices indicated that PEG + zwitterion induced not only a lower work function of ITO but also a more uniform morphology of CILs with less contact of the photoactive layer with ITO, which induced suppressed charge recombination and a higher Voc and FF. Enhanced ability in interface modification of PEG + zwitterion CILs displayed a simple and feasible approach to elevate the performance of inverted PSCs with ionic CILs. PMID:27355561

  17. High-resolution, high-throughput, positive-tone patterning of poly(ethylene glycol) by helium beam exposure through stencil masks.

    PubMed

    Cacao, Eliedonna E; Nasrullah, Azeem; Sherlock, Tim; Kemper, Steven; Kourentzi, Katerina; Ruchhoeft, Paul; Stein, Gila E; Willson, Richard C

    2013-01-01

    In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol) (SH-PEG) monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5-60 µC/cm(2) and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm(-1) and 2870 cm(-1), respectively. X-ray Photoelectron Spectroscopy (XPS) spectra showed that increasing beam doses destroy ether (C-O) bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C-C) signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT) and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP). Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver nanoparticles

  18. [Chronic ethylene glycol poisoning].

    PubMed

    Kaiser, W; Steinmauer, H G; Biesenbach, G; Janko, O; Zazgornik, J

    1993-04-30

    Over a six-week period a 60-year-old patient had several unexplained intoxication-like episodes. He finally had severe abdominal cramps with changes in the level of consciousness and oligoanuric renal failure (creatinine 4.7 mg/dl). The history, marked metabolic acidosis (pH 7.15, HCO3- 2.2 mmol/l, pCO2 6.6 mmHg) as well as raised anion residue (43 mmol/l) and the presence of oxalates in urine suggested poisoning by ethylene glycol contained in antifreeze liquid. Intensive haemodialysis adequately eliminated ethylene glycol and its toxic metabolites (glycol aldehyde, glycolic acid). Renal function returned within 10 days, although the concentrating power of the kidney remained impaired for several weeks because of interstitial nephritis. The intoxication had been caused by a defective heating-pipe system from which the antifreeze had leaked into the hot-water boiler (the patient had habitually prepared hot drinks by using water from the hot-water tap). Gas chromatography demonstrated an ethylene glycol concentration of 21 g per litre of water. PMID:8482240

  19. High power enzymatic biofuel cell based on naphthoquinone-mediated oxidation of glucose by glucose oxidase in a carbon nanotube 3D matrix.

    PubMed

    Reuillard, Bertrand; Le Goff, Alan; Agnès, Charles; Holzinger, Michael; Zebda, Abdelkader; Gondran, Chantal; Elouarzaki, Kamal; Cosnier, Serge

    2013-04-14

    We report the design of a novel glucose/O2 biofuel cell (GBFC) integrating carbon nanotube-based 3D bioelectrodes and using naphthoquinone-mediated oxidation of glucose by glucose oxidase and direct oxygen reduction by laccase. The GBFCs exhibit high open circuit voltages of 0.76 V, high current densities of 4.47 mA cm(-2), and maximum power output of 1.54 mW cm(-2), 1.92 mW mL(-1) and 2.67 mW g(-1). The GBFC is able to constantly deliver 0.56 mW h cm(-2) under discharge at 0.5 V, showing among the best in vitro performances for a GBFC. Using a charge pump, the GBFC finally powered a Light Emitting Diode (LED), demonstrating its ability to amplify micro watts to power mW-demanding electronic devices. PMID:23455694

  20. High-quality elliptical iron glycolate nanosheets: selective synthesis and chemical conversion into FexOy nanorings, porous nanosheets, and nanochains with enhanced visible-light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Tong, Guoxiu; Liu, Yun; Wu, Tong; Ye, Yucheng; Tong, Chaoli

    2015-10-01

    This paper describes an original and facile polyol-mediated solvothermal synthesis of elliptical iron glycolate nanosheets (IGNSs) combined with precursor thermal conversion into γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 porous nanosheets (PNSs), α-Fe2O3 nanochains (NCs), and elliptical Fe3O4 nanorings (NRs). The IGNSs were produced via the oxidation-reduction and co-precipitation reactions in the presence of iron(iii) salts, ethylene glycol, polyethylene glycol, and ethylenediamine. Control over Fe3+ concentration, temperature, and time can considerably modulate the size and phase of the products. The IGNSs can be transformed to γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 PNSs, α-Fe2O3 NCs, and elliptical Fe3O4 NRs by heat treatment under various annealing temperatures and ambiences. The PNSs and NCs exhibited high soft magnetic properties and coercivity, respectively. Visible-light photocatalytic activity toward RhB in the presence of H2O2 by PNSs and NCs was phase-, SBET, size-, porosity-, and local structure-dependent, following the order: α-Fe2O3 NCs > α-Fe2O3/γ-Fe2O3 PNSs > γ-Fe2O3 PNSs > IGNSs. In particular, α-Fe2O3/γ-Fe2O3 PNSs possessed significantly enhanced photocatalytic activity with good recyclability and could be conveniently separated by an applied magnetic field because of high magnetization. We believe that the as-prepared α-Fe2O3/γ-Fe2O3 PNSs have potential practical use in waste water treatment and microwave absorption.This paper describes an original and facile polyol-mediated solvothermal synthesis of elliptical iron glycolate nanosheets (IGNSs) combined with precursor thermal conversion into γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 porous nanosheets (PNSs), α-Fe2O3 nanochains (NCs), and elliptical Fe3O4 nanorings (NRs). The IGNSs were produced via the oxidation-reduction and co-precipitation reactions in the presence of iron(iii) salts, ethylene glycol, polyethylene glycol, and ethylenediamine. Control over Fe3+ concentration, temperature, and time can

  1. A colloidal suspension of nanostructured poly(N-butyl benzimidazole)-graphene sheets with high oxidase yield for analytical glucose and choline detections.

    PubMed

    Chen, Hsiao-Chien; Tsai, Rung-Ywan; Chen, Yen-Hsuan; Lee, Ren-Shen; Hua, Mu-Yi

    2013-08-20

    A colloidal suspension of nanostructured poly(N-butyl benzimidazole)-graphene sheets (PBBIns-Gs) was used to modify a gold electrode to form a three-dimensional PBBIns-Gs/Au electrode that was sensitive to hydrogen peroxide (H2O2) in the presence of acetic acid (AcOH). The positively charged nanostructured poly(N-butyl benzimidazole) (PBBIns) separated the graphene sheets (Gs) and kept them suspended in an aqueous solution. Additionally, graphene sheets (Gs) formed "diaphragms" that intercalated Gs, which separated PBBIns to prevent tight packing and enhanced the surface area. The PBBIns-Gs/Au electrode exhibited superior sensitivity toward H2O2 relative to the PBBIns-modified Au (PBBIns/Au) electrode. Furthermore, a high yield of glucose oxidase (GOD) on the PBBIns-Gs of 52.3mg GOD per 1mg PBBIns-Gs was obtained from the electrostatic attraction between the positively charged PBBIns-Gs and negatively charged GOD. The non-destructive immobilization of GOD on the surface of the PBBIns-Gs (GOD-PBBIns-Gs) retained 91.5% and 39.2% of bioactivity, respectively, relative to free GOD for the colloidal suspension of the GOD-PBBIns-Gs and its modified Au (GOD-PBBIns-Gs/Au) electrode. Based on advantages including a negative working potential, high sensitivity toward H2O2, and non-destructive immobilization, the proposed glucose biosensor based on an GOD-PBBIns-Gs/Au electrode exhibited a fast response time (5.6s), broad detection range (10μM to 10mM), high sensitivity (143.5μAmM(-1)cm(-2)) and selectivity, and excellent stability. Finally, a choline biosensor was developed by dipping a PBBIns-Gs/Au electrode into a choline oxidase (ChOx) solution for enzyme loading. The choline biosensor had a linear range of 0.1μM to 0.83mM, sensitivity of 494.9μAmM(-1)cm(-2), and detection limit of 0.02μM. The results of glucose and choline measurement indicate that the PBBIns-Gs/Au electrode provides a useful platform for the development of oxidase-based biosensors. PMID:23910974

  2. Regulation of NADPH oxidases in skeletal muscle.

    PubMed

    Ferreira, Leonardo F; Laitano, Orlando

    2016-09-01

    The only known function of NAD(P)H oxidases is to produce reactive oxygen species (ROS). Skeletal muscles express three isoforms of NAD(P)H oxidases (Nox1, Nox2, and Nox4) that have been identified as critical modulators of redox homeostasis. Nox2 acts as the main source of skeletal muscle ROS during contractions, participates in insulin signaling and glucose transport, and mediates the myocyte response to osmotic stress. Nox2 and Nox4 contribute to skeletal muscle abnormalities elicited by angiotensin II, muscular dystrophy, heart failure, and high fat diet. Our review addresses the expression and regulation of NAD(P)H oxidases with emphasis on aspects that are relevant to skeletal muscle. We also summarize: i) the most widely used NAD(P)H oxidases activity assays and inhibitors, and ii) studies that have defined Nox enzymes as protagonists of skeletal muscle redox homeostasis in a variety of health and disease conditions. PMID:27184955

  3. Oxidative phosphorylation during glycollate metabolism in mitochondria from phototrophic Euglena gracilis.

    PubMed

    Collins, N; Brown, R H; Merrett, M J

    1975-09-01

    Mitochondria were isolated by gradient centrifugation on linear sucrose gradients from broken cell suspensions of phototrophically grown Euglena gracilis. An antimycin A-sensitive but rotenone-insensitive glycollate-dependent oxygen uptake was demonstrated in isolated mitochondria. The partial reactions of glycollate-cytochrome c oxidoreductase and cytochrome c oxidase were demonstrated by using Euglena cytochrome c as exogenous electron acceptor/donor. Isolated mitochondria contain glycollate dehydrogenase and glyoxylate-glutamate aminotransferase and oxidize exogenous glycine. A P:O ratio of 1.7 was obtained for glycollate oxidation, consistent with glycollate electrons entering the Euglena respiratory chain at the flavoprotein level. The significance of these results is discussed in relation to photorespiration in algae. PMID:813630

  4. Triethylene glycol monoethyl ether

    Integrated Risk Information System (IRIS)

    Triethylene glycol monoethyl ether ; CASRN 112 - 50 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments fo

  5. Triethylene glycol monobutyl ether

    Integrated Risk Information System (IRIS)

    Triethylene glycol monobutyl ether ; CASRN 143 - 22 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments fo

  6. Propylene glycol monoethyl ether

    Integrated Risk Information System (IRIS)

    Propylene glycol monoethyl ether ; CASRN 52125 - 53 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments fo

  7. Diethylene glycol dinitrate (DEGDN)

    Integrated Risk Information System (IRIS)

    Diethylene glycol dinitrate ( DEGDN ) ; CASRN 693 - 21 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments

  8. Polyethylene Glycol 3350

    MedlinePlus

    Polyethylene glycol 3350 comes as a powder to be mixed with a liquid and taken by mouth. It is usually taken once a day as needed for up to ... to produce a bowel movement.To use the powder, follow these steps: If you are using polyethylene ...

  9. Highly selective and sensitive detection of glutathione using mesoporous silica nanoparticles capped with disulfide-containing oligo(ethylene glycol) chains.

    PubMed

    El Sayed, Sameh; Giménez, Cristina; Aznar, Elena; Martínez-Máñez, Ramón; Sancenón, Félix; Licchelli, Maurizio

    2015-01-28

    Mesoporous silica nanoparticles loaded with safranin O and capped with disulfide-containing oligo(ethylene glycol) chains were used for the selective and sensitive fluorimetric detection of glutathione. PMID:25482517

  10. Enzyme adsorption, precipitation and crosslinking of glucose oxidase and laccase on polyaniline nanofibers for highly stable enzymatic biofuel cells.

    PubMed

    Kim, Ryang Eun; Hong, Sung-Gil; Ha, Su; Kim, Jungbae

    2014-11-01

    Enzymatic biofuel cells have many great features as a small power source for medical, environmental and military applications. Both glucose oxidase (GOx) and laccase (LAC) are widely used anode and cathode enzymes for enzymatic biofuel cells, respectively. In this paper, we employed three different approaches to immobilize GOx and LAC on polyaniline nanofibers (PANFs): enzyme adsorption (EA), enzyme adsorption and crosslinking (EAC) and enzyme adsorption, precipitation and crosslinking (EAPC) approaches. The activity of EAPC-LAC was 32 and 25 times higher than that of EA-LAC and EAC-LAC, respectively. The half-life of EAPC-LAC was 53 days, while those of EA-LAC and EAC-LAC were 6 and 21 days, respectively. Similar to LAC, EAPC-GOx also showed higher activity and stability than EA-GOx and EAC-GOx. For the biofuel cell application, EAPC-GOx and EAPC-LAC were applied over the carbon papers to form enzyme anode and cathode, respectively. In order to improve the power density output of enzymatic biofuel cell, 1,4-benzoquinone (BQ) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) were introduced as the electron transfer mediators on the enzyme anode and enzyme cathode, respectively. BQ- and ABTS-mediated enzymatic biofuel cells fabricated by EAPC-GOx and EAPC-LAC showed the maximum power density output of 37.4 μW/cm(2), while the power density output of 3.1 μW/cm(2) was shown without mediators. Under room temperature and 4°C for 28 days, enzymatic biofuel cells maintained 54 and 70% of its initial power density, respectively. PMID:25248697

  11. Preparation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol microspheres for highly efficient sorption of uranium(VI).

    PubMed

    Tan, Lichao; Zhang, Xiaofei; Liu, Qi; Wang, Jun; Sun, Yanbo; Jing, Xiaoyan; Liu, Jingyuan; Song, Dalei; Liu, Lianhe

    2015-04-21

    We report a facile approach for the formation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol (Fe3O4@SiO2@Ni-L) microspheres. The structure and morphology of Fe3O4@SiO2@Ni-L are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption isotherm. The composite possesses a high specific surface area of 382 m(2) g(-1). The obtained core/shell structure is composed of a superparamagnetic core with a strong response to external fields, which are recovered readily from aqueous solutions by magnetic separation. When used as the adsorbent for uranium(vi) in water, the as-prepared Fe3O4@SiO2@Ni-L multi-structural microspheres exhibit a high adsorption capacity, which is mainly attributed to the large specific surface area and typical mesoporous characteristics of Fe3O4@SiO2@Ni-L microspheres. This work provides a promising approach for the design and synthesis of multifunctional microspheres, which can be used for water treatment, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors. PMID:25773512

  12. Self-Assembly of Polyethylene Glycol-Grafted Carbon Nanotube/Sulfur Composite with Nest-like Structure for High-Performance Lithium-Sulfur Batteries.

    PubMed

    Li, Han; Sun, Liping; Wang, Gengchao

    2016-03-01

    The novel polyethylene glycol-grafted multiwalled carbon nanotube/sulfur (PEG-CNT/S) composite cathodes with nest-like structure are fabricated through a facile combination process of liquid phase deposition and self-assembly, which consist of the active material core of sulfur particle and the conductive shell of PEG-CNT network. The unique architecture not only provides a short and rapid charge transfer pathway to improve the reaction kinetics but also alleviates the volume expansion of sulfur during lithiation and minimizes the diffusion of intermediate polysulfides. Such an encouraging electrochemical environment ensures the excellent rate capability and high cycle stability. As a result, the as-prepared PEG-CNT/S composite with sulfur content of 75.9 wt % delivers an initial discharge capacity of 1191 and 897 mAh g(-1) after 200 cycles at 0.2 C with an average Coulombic efficiency of 99.5%. Even at a high rate of 2 C, an appreciable capacity of 723 mAh g(-1) can still be obtained. PMID:26890092

  13. The high-spin cytochrome o' component of the cytochrome bo-type quinol oxidase in membranes from Escherichia coli: formation of the primary oxygenated species at low temperatures is characterized by a slow 'on' rate and low dissociation constant.

    PubMed

    Poole, R K; Salmon, I; Chance, B

    1994-05-01

    Cytochromes b and o in membrane vesicles from aerobically grown Escherichia coli were readily reduced by succinate; one cytochrome, which we propose should be called cytochrome o', reacted with CO in the Fe(II) state to give a photodissociable CO adduct. The photodissociation spectrum (photolysed minus pre-photolysis) at sub-zero temperatures had a relatively high gamma/alpha absorbance ratio, indicating a high-spin haem, which, in the reduced state, probably contributes little to the sharp alpha absorbance of the oxidase complex in membranes. Reaction with oxygen of the unliganded high-spin haem between -132 degrees C and -95 degrees C following photolytic activation gave a product that is identified as the oxygenated form, being spectrally similar to, but not identical with, the CO adduct. In membranes, the forward velocity constant at -95 degrees C was 61 M-1s-1, and the dissociation constant was 1.6 x 10(-5) M O2, as it is in intact cells. These data clearly distinguish the oxygen-trapping strategy of the cytochrome o' in this oxidase from that of cytochrome a3 and also suggest that the presence of the soluble flavohaemoglobin (Hmp) in intact cells is without effect on such measurements of the primary oxygen reaction. In view of recent findings that this oxidase complex contains predominantly one mole of haem O and one of haem B, a revised nomenclature for the oxidase complex is proposed, namely, cytochrome bo'. PMID:8025668

  14. Treatment of high-strength ethylene glycol waste water in an expanded granular sludge blanket reactor: use of PVA-gel beads as a biocarrier.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    Industrial-scale use of polyvinyl alcohol (PVA)-gel beads as biocarriers is still not being implemented due to the lack of understanding regarding the optimal operational parameters. In this study, the parameters for organic loading rate (OLR), alkalinity, recycle rate, and addition of trace elements were investigated in an expanded granular sludge blanket reactor (EGSB) treating high-strength ethylene glycol wastewater (EG) with PVA-gel beads as biocarrier. Stable chemical oxygen demand (COD) removal efficiencies of 95 % or greater were achieved, and continuous treatment was demonstrated with appropriate parameters being an OLR of 15 kg COD/m(3)/day, NaHCO3 added at 400 mg/L, a recycle rate of 15 L/h, and no addition of trace elements addition. A biogas production yield rate of 0.24 m(3)/kg COD was achieved in this study. A large number of long rod-shaped bacteria (Methanosaeta), were found with low acetate concentration in the EGSB reactor. PMID:27386305

  15. High colloidal stability of gold nanorods coated with a peptide-ethylene glycol: Analysis by cyanide-mediated etching and nanoparticle tracking analysis.

    PubMed

    Free, Paul; Conger, Gao; Siji, Wu; Zhang, Jing Bo; Fernig, David G

    2016-10-01

    The stability of gold nanorods was assessed following coating with various charged or uncharged ligands, mostly peptides. Highly stable monodispersed gold nanorods were obtained by coating CTAB-stabilized gold nanorods with a pentapeptide with C-terminal ethylene glycol units (peptide-EG). UV-vis spectroscopy of these nanorods suspended in saline solutions indicated no signs of aggregation, and they were easily purified using size-exclusion chromatography. A more stringent measure of nanorod stability involved observing changes in the UV-vis absorbance of gold nanorods subjected to etching with cyanide. The λmax absorbance of peptide-EG coated nanorods red-shifted in etchant solution. The hypothesis that changes in the nanorod aspect ratio led to this red-shift was confirmed by TEM analysis, which showed pit formation along the transverse axis. The etching process was followed in solution using nanoparticle tracking analysis. The red-shift was shown to occur while the particles remained mono-dispersed, and so was not due to aggregation. Adding both etchant solution and peptide-EG to the nanorods was further shown to allow modulation of the Δλmax red-shift and increase the etchant resistance of peptide-EG nanorods. Thus, very stable gold nanorods can be produced using the peptide-EG coating approach and their optical properties modulated with etchant. PMID:27455407

  16. Synthesis and characterizations of palladium catalysts with high activity and stability for formic acid oxidation by hydrogen reduction in ethylene glycol at room temperature

    NASA Astrophysics Data System (ADS)

    Wu, Meixia; Li, Muwu; Wu, Xin; Li, Yuexia; Zeng, Jianhuang; Liao, Shijun

    2015-10-01

    In this work, a Pd/C catalyst with high activity as well as excellent stability has been prepared by hydrogen gas reduction of Pd(II) precursor in ethylene glycol solution with the assistance of appropriate amount of sodium citrate. Pd nanoparticles with an average particle size of 3.8 nm and excellent uniformity are obtained. The Pd/C catalyst synthesized in this work shows an electrochemical surface area of 68.6 m2 g-1 and displays activities of 819 A g-1. Strikingly, the Pd/C catalyst also exhibits excellent stability, which has been confirmed by its slow activity decay under repeated potential cycles as well as chronoamperometric test. The activity for Pd/C at the 300th and 500th cycle remains at 5.5 and 2.4 mA cm-2, respectively, which is 25% and 11% of its initial value, respectively. The oxidation currents at the Pd/C and Pd/C-Citrate (control) at 0 V decrease to 44% and 25% of their initial values. Transmission electron microscopy observations on the Pd/C catalyst after 1000 potential cycles reveal that, in addition to carbon support corrosion, Pd agglomeration together with more serious Pd dissolution occur at the same time, leading to a decrease of the electrocatalytic performance.

  17. Safety of poly (ethylene glycol)-coated perfluorodecalin-filled poly (lactide-co-glycolide) microcapsules following intravenous administration of high amounts in rats

    PubMed Central

    Ferenz, Katja B.; Waack, Indra N.; Laudien, Julia; Mayer, Christian; Broecker-Preuss, Martina; Groot, Herbert de; Kirsch, Michael

    2014-01-01

    The host response against foreign materials designates the biocompatibility of intravenously administered microcapsules and thus, widely affects their potential for subsequent clinical use as artificial oxygen/drug carriers. Therefore, body distribution and systemic parameters, as well as markers of inflammation and indicators of organ damage were carefully evaluated after administration of short-chained poly (vinyl alcohol, (PVA)) solution or poly (ethylene glycol (PEG))-shielded perfluorodecalin-filled poly (d,l-lactide-co-glycolide, PFD-filled PLGA) microcapsules into Wistar rats. Whereas PVA infusion was well tolerated, all animals survived the selected dose of 1247 mg microcapsules/kg body weight but showed marked toxicity (increased enzyme activities, rising pro-inflammatory cytokines and complement factors) and developed a mild metabolic acidosis. The observed hypotension emerging immediately after start of capsule infusion was transient and mean arterial blood pressure restored to baseline within 70 min. Microcapsules accumulated in spleen and liver (but not in other organs) and partly occluded hepatic microcirculation reducing sinusoidal perfusion rate by about 20%. Intravenous infusion of high amounts of PFD-filled PLGA microcapsules was tolerated temporarily but associated with severe side effects such as hypotension and organ damage. Short-chained PVA displays excellent biocompatibility and thus, can be utilized as emulsifier for the preparation of drug carriers designed for intravenous use. PMID:25756002

  18. An overview on alcohol oxidases and their potential applications.

    PubMed

    Goswami, Pranab; Chinnadayyala, Soma Sekhar R; Chakraborty, Mitun; Kumar, Adepu Kiran; Kakoti, Ankana

    2013-05-01

    Alcohol oxidases (Alcohol: O₂ Oxidoreductase; EC 1.1.3.x) are flavoenzymes that catalyze the oxidation of alcohols to the corresponding carbonyl compounds with a concomitant release of hydrogen peroxide. Based on substrate specificity, alcohol oxidases may be categorized broadly into four different groups namely, (a) short chain alcohol oxidase (SCAO), (b) long chain alcohol oxidase (LCAO), (c) aromatic alcohol oxidase (AAO), and (d) secondary alcohol oxidase (SAO). The sources reported for these enzymes are mostly limited to bacteria, yeast, fungi, plant, insect, and mollusks. However, the quantum of reports for each category of enzymes considerably varies across these sources. The enzymes belonging to SCAO and LCAO are intracellular in nature, whereas AAO and SAO are mostly secreted to the medium. SCAO and LCAO are invariably reported as multimeric proteins with very high holoenzyme molecular masses, but the molecular characteristics of these enzymes are yet to be clearly elucidated. One of the striking features of the alcohol oxidases that make them distinct from the widely known alcohol dehydrogenase is the avidly bound cofactor to the redox center of these enzymes that obviate the need to supplement cofactor during the catalytic reaction. These flavin-based redox enzymes have gained enormous importance in the development of various industrial processes and products primarily for developing biosensors and production of various industrially useful carbonyl compounds. The present review provides an overview on alcohol oxidases from different categories focusing research on these oxidases during the last decade along with their potential industrial applications. PMID:23525937

  19. Impact of high pressure processing on color, bioactive compounds, polyphenol oxidase activity, and microbiological attributes of pumpkin purée.

    PubMed

    González-Cebrino, Francisco; Durán, Rocío; Delgado-Adámez, Jonathan; Contador, Rebeca; Bernabé, Rosario Ramírez

    2016-04-01

    Physicochemical parameters, bioactive compounds' content (carotenoids and total phenols), total antioxidant activity, and enzymatic activity of polyphenol oxidase (PPO) were evaluated after high pressure processing (HPP) on a pumpkin purée (cv. 'Butternut'). Three pressure levels (400, 500, and 600 MPa) were combined with three holding times (200, 400, and 600 s). The applied treatments reduced the levels of total aerobic mesophilic (TAM), total psychrophilic and psychrotrophic bacteria (TPP), and molds and yeasts (M&Y). All applied treatments did not affect enzymatic activity of PPO. Pressure level increased CIE L* values, which could enhance the lightness perception of high pressure (HP)-treated purées. No differences were found between the untreated and HP-treated purées regarding total phenols and carotenoids content (lutein, α-carotene, and β-carotene) and total antioxidant activity. HPP did not affect most quality parameters and maintained the levels of bioactive compounds. However, it did not achieve the complete inhibition of PPO, which could reduce the shelf-life of the pumpkin purée. PMID:26123635

  20. Aldehyde oxidase 1 is highly abundant in hepatic steatosis and is downregulated by adiponectin and fenofibric acid in hepatocytes in vitro

    SciTech Connect

    Neumeier, Markus; Weigert, Johanna; Schaeffler, Andreas; Weiss, Thomas S.; Schmidl, Christian; Buettner, Roland; Bollheimer, Cornelius; Aslanidis, Charalampos; Schoelmerich, Juergen; Buechler, Christa . E-mail: christa.buechler@klinik.uni-regensburg.de

    2006-11-24

    Adiponectin protects the liver from steatosis caused by obesity or alcohol and therefore the influence of adiponectin on human hepatocytes was analyzed. GeneChip experiments indicated that recombinant adiponectin downregulates aldehyde oxidase 1 (AOX1) expression and this was confirmed by real-time RT-PCR and immunoblot. AOX1 is a xenobiotic metabolizing protein and produces reactive oxygen species (ROS), that promote cell damage and fibrogenesis. Adiponectin and fenofibric acid activate peroxisome proliferator-activated receptor-{alpha} (PPAR-{alpha}) and both suppress AOX1 protein and this is blocked by the PPAR-{alpha} antagonist RU486. Obesity is associated with low adiponectin, reduced hepatic PPAR-{alpha} activity and fatty liver, and AOX1 was found induced in the liver of rats on a high-fat diet when compared to controls. Free fatty acids and leptin, that are elevated in obesity, failed to upregulate AOX1 in vitro. The current data indicate that adiponectin reduces AOX1 by activating PPAR-{alpha} whereas fatty liver disease is associated with elevated hepatic AOX1. High AOX1 may be associated with higher ROS well described to induce fibrogenesis in liver tissue but may also influence drug metabolism and activity.

  1. Effects of High Pressure Homogenization on the Activity, Stability, Kinetics and Three-Dimensional Conformation of a Glucose Oxidase Produced by Aspergillus niger

    PubMed Central

    Tribst, Alline Artigiani Lima; Cota, Júnio; Murakami, Mario Tyago; Cristianini, Marcelo

    2014-01-01

    High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5–6.0 and a remarkable activity increase (30–300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO. PMID:25061935

  2. A high-performance glucose biosensor using covalently immobilised glucose oxidase on a poly(2,6-diaminopyridine)/carbon nanotube electrode.

    PubMed

    Ali Kamyabi, Mohammad; Hajari, Nasim; Turner, Anthony P F; Tiwari, Ashutosh

    2013-11-15

    A highly-sensitive glucose biosensor amenable to ultra-miniaturisation was fabricated by immobilisation of glucose oxidase (GOx), onto a poly(2,6-diaminopyridine)/multi-walled carbon nanotube/glassy carbon electrode (poly(2,6-DP)/MWNT/GCE). Cyclic voltammetry was used for both the electrochemical synthesis of poly-(2,6-DP) on the surface of a MWNT-modified GC electrode, and characterisation of the polymers deposited on the GC electrode. The synergistic effect of the high active surface area of both the conducting polymer, i.e., poly-(2,6-DP) and MWNT gave rise to a remarkable improvement in the electrocatalytic properties of the biosensor. The transfer coefficient (α), heterogeneous electron transfer rate constant and Michaelis-Menten constant were calculated to be 0.6, 4 s(-1) and 0.20 mM at pH 7.4, respectively. The GOx/poly(2,6-DP)/MWNT/GC bioelectrode exhibited two linear responses to glucose in the concentration ranging from 0.42 μM to 8.0 mM with a correlation coefficient of 0.95, sensitivity of 52.0 μA mM(-1) cm(-2), repeatability of 1.6% and long-term stability, which could make it a promising bioelectrode for precise detection of glucose in the biological samples. PMID:24148477

  3. Inactivation, aggregation, secondary and tertiary structural changes of germin-like protein in Satsuma mandarine with high polyphenol oxidase activity induced by ultrasonic processing.

    PubMed

    Huang, Nana; Cheng, Xi; Hu, Wanfeng; Pan, Siyi

    2015-02-01

    The inhibition of Polyphenol oxidase (PPO) in plants has been widely researched for their important roles in browning reaction. A newly found germin-like protein (GLP) with high PPO activity in Satsuma mandarine was inactivated by low-frequency high-intensity ultrasonic (20 kHz) processing. The effects of ultrasound on PPO activity and structure of GLP were investigated using dynamic light scattering (DLS) analysis, transmission electron microscopy (TEM), circular dichroism (CD) spectral measurement and fluorescence spectral measurement. The lowest PPO activity achieved was 27.4% following ultrasonication for 30 min at 400 W. DLS analysis showed ultrasound caused both aggregation and dissociation of GLP particles. TEM images also demonstrated protein aggregation phenomena. CD spectra exhibited a certain number of loss in α-helix structure content. Fluorescence spectra showed remarkable increase in fluorescence intensity with tiny blue-shift following ultrasonication. In conclusion, ultrasound applied in this study induced structural changes of GLP and eventually inactivated PPO activity. PMID:25522206

  4. Highly sensitive poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] brush-based flow-through microarray immunoassay device.

    PubMed

    Liu, Yingshuai; Wang, Wei; Hu, Weihua; Lu, Zhisong; Zhou, Xiaoqun; Li, Chang Ming

    2011-08-01

    Flow-through immunoassay is an attractive method for fast, inexpensive and high-throughput protein analyses. However, its practical application is limited by low sensitivity. In this work, a highly sensitive flow-through microarray immunoassay device is developed, in which a poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] (P(GMA-co-PEGMA)) brush as a flexible matrix is uniformly coated on a glass slide through a purge-free surface-initiated atom transfer radical polymerization (SI-ATRP) to immobilize capture proteins for a larger loading capacity and higher bioactivity while allowing easy target access to the brush-attached probes for efficient antibody-antigen (Ab-Ag) bindings. The integrated device is then constructed by simply laminating the protein-arrayed slide onto a ready-for-bonding double-sided adhesive tape-attached poly(methyl methacrylate) (PMMA) microfluidic structure. As a demonstration, a parallel microarray panel is designed to perform flow-through immunoassays for good detection flexibility and simultaneous analysis of various samples. The limit of detection (LOD) of 1-10 pg/mL for detected target proteins is achieved, which is one to two orders better than those of reported flow-through immunoassays. The device also demonstrates significantly reduced total assay time over the static microarray immunoassay. The rapid and sensitive detection can be mainly ascribed to the P(GMA-co-PEGMA) brushed substrate, of which both the hydrophilicity from its PEG component and the binding capability from its GMA moiety result in higher protein loading capacity, lower nonspecific adsorption, and higher Ab-Ag binding efficiency. The integrated microfluidic device was further used to detect an important cancer biomarker carcinoembryonic antigen (CEA) in serum and achieved a LOD of 10 pg/mL, demonstrating its great potential for clinical applications. PMID:21547537

  5. Green tea extract with polyethylene glycol-3350 reduces body weight and improves glucose tolerance in db/db and high-fat diet mice.

    PubMed

    Park, Jae-Hyung; Choi, Yoon Jung; Kim, Yong Woon; Kim, Sang Pyo; Cho, Ho-Chan; Ahn, Shinbyoung; Bae, Ki-Cheor; Im, Seung-Soon; Bae, Jae-Hoon; Song, Dae-Kyu

    2013-08-01

    Green tea extract (GTE) is regarded to be effective against obesity and type 2 diabetes, but definitive evidences have not been proven. Based on the assumption that the gallated catechins (GCs) in GTE attenuate intestinal glucose and lipid absorption, while enhancing insulin resistance when GCs are present in the circulation through inhibiting cellular glucose uptake in various tissues, this study attempted to block the intestinal absorption of GCs and prolong their residence time in the lumen. We then observed whether GTE containing the nonabsorbable GCs could ameliorate body weight (BW) gain and glucose intolerance in db/db and high-fat diet mice. Inhibition of the intestinal absorption of GCs was accomplished by co-administering the nontoxic polymer polyethylene glycol-3350 (PEG). C57BLKS/J db/db and high-fat diet C57BL/6 mice were treated for 4 weeks with drugs as follows: GTE, PEG, GTE+PEG, voglibose, or pioglitazone. GTE mixed with meals did not have any ameliorating effects on BW gain and glucose intolerance. However, the administration of GTE plus PEG significantly reduced BW gain, insulin resistance, and glucose intolerance, without affecting food intake and appetite. The effect was comparable to the effects of an α-glucosidase inhibitor and a peroxisome proliferator-activated receptor-γ/α agonist. These results indicate that prolonging the action of GCs of GTE in the intestinal lumen and blocking their entry into the circulation may allow GTE to be used as a prevention and treatment for both obesity and obesity-induced type 2 diabetes. PMID:23620335

  6. High aspect ratio nanoimprinted grooves of poly(lactic-co-glycolic acid) control the length and direction of retraction fibers during fibroblast cell division.

    PubMed

    Su, Yi-Hsuan; Chiang, Po-Chieh; Cheng, Li-Jing; Lee, Chau-Hwang; Swami, Nathan S; Chou, Chia-Fu

    2015-01-01

    Retraction fibers (RFs) determine orientation of the cell division axis and guide the spreading of daughter cells. Long and unidirectional RFs, which are especially apparent during mitosis of cells in three-dimensional (3D) environments, enable improved control over cell fate, following division. However, 3D gel environments lack the cues necessary for predetermining the orientation of RFs to direct tissue architecture. While patterning of focal adhesion regions by microcontact printing can determine orientation of the RFs through enhancing focal adhesion numbers along particular directions, the RFs remain short due to the two-dimensional culture environment. Herein, the authors demonstrate that nanoimprinted grooves of polylactic acid glycolic acid (PLGA) with a high aspect ratio (A.R. of 2.0) can provide the cues necessary to control the direction of RFs, as well as enable the maintenance of long and unidirectional RFs as observed within 3D cultures, while the same is not possible with PLGA grooves of lower A.R. (1.0 or lower). Based on enhanced levels of contact guidance of premitotic fibroblast protrusions at high A.R. grooves and deeper levels of focal adhesion due to filopodia extensions into these grooves, it is suggested that submicron (800 nm width) PLGA grooves with A.R. of 2 are capable of supporting mechanical forces from cell protrusions to a greater depth, thereby enabling the maintenance of the protrusions as long and unidirectional RFs during cell division. Given the scalability and versatility of nanoimprint techniques, the authors envision a platform for designing nanostructures to direct tissue regeneration and developmental biology. PMID:26652706

  7. High resolution crystal structure of rat long chain hydroxy acid oxidase in complex with the inhibitor 4-carboxy-5-[(4-chlorophenyl)sulfanyl]-1, 2, 3-thiadiazole. Implications for inhibitor specificity and drug design

    SciTech Connect

    Chen, Zhi-wei; Vignaud, Caroline; Jaafar, Adil; Lévy, Bernard; Guéritte, Françoise; Guénard, Daniel; Lederer, Florence; Mathews, F. Scott

    2012-05-24

    Long chain hydroxy acid oxidase (LCHAO) is responsible for the formation of methylguanidine, a toxic compound with elevated serum levels in patients with chronic renal failure. Its isozyme glycolate oxidase (GOX), has a role in the formation of oxalate, which can lead to pathological deposits of calcium oxalate, in particular in the disease primary hyperoxaluria. Inhibitors of these two enzymes may have therapeutic value. These enzymes are the only human members of the family of FMN-dependent L-2-hydroxy acid-oxidizing enzymes, with yeast flavocytochrome b{sub 2} (Fcb2) among its well studied members. We screened a chemical library for inhibitors, using in parallel rat LCHAO, human GOX and the Fcb2 flavodehydrogenase domain (FDH). Among the hits was an inhibitor, CCPST, with an IC{sub 50} in the micromolar range for all three enzymes. We report here the crystal structure of a complex between this compound and LCHAO at 1.3 {angstrom} resolution. In comparison with a lower resolution structure of this enzyme, binding of the inhibitor induces a conformational change in part of the TIM barrel loop 4, as well as protonation of the active site histidine. The CCPST interactions are compared with those it forms with human GOX and those formed by two other inhibitors with human GOX and spinach GOX. These compounds differ from CCPST in having the sulfur replaced with a nitrogen in the five-membered ring as well as different hydrophobic substituents. The possible reason for the {approx}100-fold difference in affinity between these two series of inhibitors is discussed. The present results indicate that specificity is an issue in the quest for therapeutic inhibitors of either LCHAO or GOX, but they may give leads for this quest.

  8. Enhanced incorporation of tritium into glycolate during photosynthesis by tobacco leaf tissue in the presence of tritiated water

    SciTech Connect

    Peterson, R.B.

    1982-01-01

    Tobacco (Nicotiana tabacum var. Havana Seed) leaf discs were allowed to photosynthesize for 3 to 20 minutes in the present of /sup 14/CO/sub 2/ and /sup 3/H/sub 2/O. Several metabolites of the Calvin cycle and photorespiratory pathway were isolated and purified and the /sup 3/H:/sup 14/C values measured. Glycolate had a 5- to 10-fold higher /sup 3/H:/sup 14/C than the Calvin cycle intermediate 3- phosphoglyceric acid, or its end product sucrose. The glycolate oxidase inhibitor ..cap alpha..-hydroxy-2-pyridinemethanesulfonic acid caused glycolate to accumulate in the tissue and lowered the /sup 3/H:/sup 14/C in glycolate to a value similar to that in 3-phosphoglyceric acid. Phosphoglycolate, a possible precursor of glycolate arising from the Calvin cycle, exhibited a /sup 3/H:/sup 14/C value similar 3-phosphoglyceric acid under all conditions. The finding of a /sup 3/H enrichment in glycolate suggests that another source of glycolate, possibly the reduction of glyoxylate, exists in leaf tissue. Analyses of incorporation of /sup 3/H into the pro-2R and pro-2S hydrogens of glycolate, in the presence and absence of ..cap alpha..-hydroxy-2-pyridinemethanesulfonic acid, suggest an alternative source of glycolate. Biochemical mechanisms to account for /sup 3/H enrichment into glycolate are evaluated.

  9. Glycol Ethers As Groundwater Contaminants

    NASA Astrophysics Data System (ADS)

    Ross, Benjamin; Johannson, Gunnar; Foster, Gregory D.; Eckel, William P.

    1992-01-01

    Ether derivatives of dihydroxy alcohols, which are formed from ethylene or propylene, comprise an important group of groundwater contaminants known as glycol ethers. Compounds in this group are used as solvents, cleaning agents, and emulsifiers in many chemical products and manufacturing operations. Glycol ethers have been associated with a variety of toxic effects, and some compounds in the group are relatively potent teratogens. The limited information available suggests that glycol ethers are contaminants in groundwater, especially in anaerobic plumes emanating from disposal of mixed industrial and household waste. Most methods used to analyze groundwater samples cannot adequately detect μg/? (ppb) concentrations of glycol ethers, and the existing methods perform worst for the most widely used and toxic species. A new method capable of analyzing μg/? concentrations of glycol ethers was recently developed, and its use is recommended for groundwater samples where glycol ethers are likely to be present.

  10. NADPH oxidases: new actors in thyroid cancer?

    PubMed

    Ameziane-El-Hassani, Rabii; Schlumberger, Martin; Dupuy, Corinne

    2016-08-01

    Hydrogen peroxide (H2O2) is a crucial substrate for thyroid peroxidase, a key enzyme involved in thyroid hormone synthesis. However, as a potent oxidant, H2O2 might also be responsible for the high level of oxidative DNA damage observed in thyroid tissues, such as DNA base lesions and strand breakages, which promote chromosomal instability and contribute to the development of tumours. Although the role of H2O2 in thyroid hormone synthesis is well established, its precise mechanisms of action in pathological processes are still under investigation. The NADPH oxidase/dual oxidase family are the only oxidoreductases whose primary function is to produce reactive oxygen species. As such, the function and expression of these enzymes are tightly regulated. Thyrocytes express dual oxidase 2, which produces most of the H2O2 for thyroid hormone synthesis. Thyrocytes also express dual oxidase 1 and NADPH oxidase 4, but the roles of these enzymes are still unknown. Here, we review the structure, expression, localization and function of these enzymes. We focus on their potential role in thyroid cancer, which is characterized by increased expression of these enzymes. PMID:27174022

  11. Smart surface coating of drug nanoparticles with cross-linkable polyethylene glycol for bio-responsive and highly efficient drug delivery

    NASA Astrophysics Data System (ADS)

    Wei, Weijia; Zhang, Xiujuan; Chen, Xianfeng; Zhou, Mengjiao; Xu, Ruirui; Zhang, Xiaohong

    2016-04-01

    Many drug molecules can be directly used as nanomedicine without the requirement of any inorganic or organic carriers such as silica and liposome nanostructures. This new type of carrier-free drug nanoparticles (NPs) has great potential in clinical treatment because of its ultra-high drug loading capacity and biodegradability. For practical applications, it is essential for such nanomedicine to possess robust stability and minimal premature release of therapeutic molecules during circulation in the blood stream. To meet this requirement, herein, we develop GSH-responsive and crosslinkable amphiphilic polyethylene glycol (PEG) molecules to modify carrier-free drug NPs. These PEG molecules can be cross-linked on the surface of the NPs to endow them with greater stability and the cross-link is sensitive to intracellular environment for bio-responsive drug release. With this elegant design, our experimental results show that the liberation of DOX from DOX-cross-linked PEG NPs is dramatically slower than that from DOX-non-cross-linked PEG NPs, and the DOX release profile can be controlled by tuning the concentration of the reducing agent to break the cross-link between PEG molecules. More importantly, in vivo studies reveal that the DOX-cross-linked PEG NPs exhibit favorable blood circulation half-life (>4 h) and intense accumulation in tumor areas, enabling effective anti-cancer therapy. We expect this work will provide a powerful strategy for stabilizing carrier-free nanomedicines and pave the way to their successful clinical applications in the future.Many drug molecules can be directly used as nanomedicine without the requirement of any inorganic or organic carriers such as silica and liposome nanostructures. This new type of carrier-free drug nanoparticles (NPs) has great potential in clinical treatment because of its ultra-high drug loading capacity and biodegradability. For practical applications, it is essential for such nanomedicine to possess robust stability

  12. Polyethylene Glycol Propionaldehydes

    NASA Technical Reports Server (NTRS)

    Harris, Joe M.; Sedaghat-Herati, Mohammad R.; Karr, Laurel J.

    1992-01-01

    New class of compounds derived from polyethylene glycol (PEG's) namely, PEG-propionaldehydes, offers two important advantages over other classes of PEG aldehyde derivatives: compounds exhibit selective chemical reactivity toward amino groups and are stable in aqueous environment. PEG's and derivatives used to couple variety of other molecules, such as, to tether protein molecules to surfaces. Biotechnical and biomedical applications include partitioning of two phases in aqueous media; immobilization of such proteins as enzymes, antibodies, and antigens; modification of drugs; and preparation of protein-rejecting surfaces. In addition, surfaces coated with PEG's and derivatives used to control wetting and electroosmosis. Another potential application, coupling to aminated surfaces.

  13. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings

    SciTech Connect

    Wang, Yapei; Pitet, Louis M.; Finlay, John A.; Brewer, Lenora H.; Cone, Gemma; Betts, Douglas E.; Callow, Maureen E.; Callow, James A.; Wendt, Dean E.; Hillmyer, Marc A.; DeSimone, Joseph M.

    2013-03-07

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M{sub w} = 1500 g mol{sup -1}) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M{sub w} = 300, 475, 1100 g mol{sup -1}), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  14. The composition of milk xanthine oxidase

    PubMed Central

    Hart, L. I.; McGartoll, Mary A.; Chapman, Helen R.; Bray, R. C.

    1970-01-01

    The composition of milk xanthine oxidase has been reinvestigated. When the enzyme is prepared by methods that include a selective denaturation step in the presence of sodium salicylate the product is obtained very conveniently and in high yield, and is homogeneous in the ultracentrifuge and in recycling gel filtration. It has specific activity higher than previously reported preparations of the enzyme and its composition approximates closely to 2mol of FAD, 2g-atoms of Mo and 8g-atoms of Fe/mol of protein (molecular weight about 275000). In contrast, when purely conventional preparative methods are used the product is also homogeneous by the above criteria but has a lower specific activity and is generally comparable to the crystallized enzyme described previously. Such samples also contain 2mol of FAD/mol of protein but they have lower contents of Mo (e.g. 1.2g-atom/mol). Amino acid compositions for the two types of preparation are indistinguishable. These results confirm the previous conclusion that conventional methods give mixtures of xanthine oxidase with an inactive modification of the enzyme now termed `de-molybdo-xanthine oxidase', and show that salicylate can selectively denature the latter. The origin of de-molybdo-xanthine oxidase was investigated. FAD/Mo ratios show that it is present not only in enzyme purified by conventional methods but also in `milk microsomes' (Bailie & Morton, 1958) and in enzyme samples prepared without proteolytic digestion. We conclude that it is secreted by cows together with the active enzyme and we discuss its occurrence in the preparations of other workers. Studies on the milks of individual cows show that nutritional rather than genetic factors determine the relative amounts of xanthine oxidase and de-molybdo-xanthine oxidase. A second inactive modification of the enzyme, now termed `inactivated xanthine oxidase', causes variability in activity relative to E450 or to Mo content and formation of it decreases these ratios

  15. Novel biotreatment process for glycol waters

    SciTech Connect

    Raja, L.M.V.; Elamvaluthy, G.; Palaniappan, R.; Krishnan, R.M.

    1991-12-31

    Propylene oxide (PO), propylene glycol (PG), and polyols are produced from propylene via propylene chlorohydrin. Effluents from these plants contain biological oxygen demand/chemical oxygen demand (BOD/COD) loads besides high chloride concentrations. The high salinity poses severe problem to adopt conventional methods like activated sludge processes. Presently, a simple, economically viable and versatile microbiological process has been developed to get more than 90% biodegradation in terms of BOD/COD, utilizing specially developed Pseudomonas and Aerobacter. The process can tolerate high salinity up to 10 wt% NaCl or 5 wt% CaCl{sub 2} and can withstand wide variations in pH (5.5-11.0) and temperature (15-45{degrees}C). The biodegradation of glycols involves two steps. The enzymatic conversion of glycols to carboxylic and hydroxycarboxylic acids is aided by Pseudoomonas. Further degradation to CO{sub 2} and H{sub 2}O by carboxylic acid utilizing Aerobacter, and possible metabolic degradative pathway of glycols are discussed. Various process parameters obtained in the lab scale (50 L bioreactor) and pilot scale (20 m{sup 3} bioreactor), and unique features of our process are also discussed.

  16. High-performance glucose biosensor based on chitosan-glucose oxidase immobilized polypyrrole/Nafion/functionalized multi-walled carbon nanotubes bio-nanohybrid film.

    PubMed

    Shrestha, Bishnu Kumar; Ahmad, Rafiq; Mousa, Hamouda M; Kim, In-Gi; Kim, Jeong In; Neupane, Madhav Prasad; Park, Chan Hee; Kim, Cheol Sang

    2016-11-15

    A highly electroactive bio-nanohybrid film of polypyrrole (PPy)-Nafion (Nf)-functionalized multi-walled carbon nanotubes (fMWCNTs) nanocomposite was prepared on the glassy carbon electrode (GCE) by a facile one-step electrochemical polymerization technique followed by chitosan-glucose oxidase (CH-GOx) immobilization on its surface to achieve a high-performance glucose biosensor. The as-fabricated nanohybrid composite provides high surface area for GOx immobilization and thus enhances the enzyme-loading efficiency. The structural characterization revealed that the PPy-Nf-fMWCNTs nanocomposite films were uniformly formed on GCE and after GOx immobilization, the surface porosities of the film were decreased due to enzyme encapsulation inside the bio-nanohybrid composite materials. The electrochemical behavior of the fabricated biosensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. The results indicated an excellent catalytic property of bio-nanohybrid film for glucose detection with improved sensitivity of 2860.3μAmM(-1)cm(-2), the linear range up to 4.7mM (R(2)=0.9992), and a low detection limit of 5μM under a signal/noise (S/N) ratio of 3. Furthermore, the resulting biosensor presented reliable selectivity, better long-term stability, good repeatability, reproducibility, and acceptable measurement of glucose concentration in real serum samples. Thus, this fabricated biosensor provides an efficient and highly sensitive platform for glucose sensing and can open up new avenues for clinical applications. PMID:27485503

  17. Ascorbic acid and L-gulonolactone oxidase in lagomorphs.

    PubMed

    Jenness, R; Birney, E C; Ayaz, K L

    1978-01-01

    1. The activity of L-gulonolactone oxidase (EC 1.1.3.8) in the liver of eastern cottontail rabbits (Sylvilagus floridanus) is about 10-fold greater in winter than in summer. 2. L-gulonolactone oxidase activity is low and tissue ascorbate high during all seasons in snowshoe hares (Lepus americanus). 3. Liver contents of ascorbate fall to low levels in L. americanus fed on rabbit chow in the laboratory. 4. The activity of L-gulonolactone oxidase in liver of Sylvilagus and Oryctolagus is depressed by feeding high levels of L-ascorbic acid. 5. The New Zealand White breed of domestic rabbit (Oryctolagus cuniculus) has considerably higher levels of L-gulonolactone oxidase and liver ascorbate than does the Dutch breed. 6. In a wild population of Oryctolagus sampled in Australia L-gulonolactone oxidase levels were intermediate between those of the two domestic breeds and more variable than either. PMID:318384

  18. Interstellar Antifreeze: Ethylene Glycol

    NASA Astrophysics Data System (ADS)

    Hollis, J. M.; Lovas, F. J.; Jewell, P. R.; Coudert, L. H.

    2002-05-01

    Interstellar ethylene glycol (HOCH2CH2OH) has been detected in emission toward the Galactic center source Sagittarius B2(N-LMH) by means of several millimeter-wave rotational torsional transitions of its lowest energy conformer. The types and kinds of molecules found to date in interstellar clouds suggest a chemistry that favors aldehydes and their corresponding reduced alcohols-e.g., formaldehyde (H2CO)/methanol (CH3OH), acetaldehyde (CH3CHO)/ethanol (CH3CH2OH). Similarly, ethylene glycol is the reduced alcohol of glycolaldehyde (CH2OHCHO), which has also been detected toward Sgr B2(N-LMH). While there is no consensus as to how any such large complex molecules are formed in the interstellar clouds, atomic hydrogen (H) and carbon monoxide (CO) could form formaldehyde on grain surfaces, but such surface chemistry beyond that point is uncertain. However, laboratory experiments have shown that the gas-phase reaction of atomic hydrogen (H) and solid-phase CO at 10-20 K can produce formaldehyde and methanol and that alcohols and other complex molecules can be synthesized from cometary ice analogs when subject to ionizing radiation at 15 K. Thus, the presence of aldehyde/reduced alcohol pairs in interstellar clouds implies that such molecules are a product of a low-temperature chemistry on grain surfaces or in grain ice mantles. This work suggests that aldehydes and their corresponding reduced alcohols provide unique observational constraints on the formation of complex interstellar molecules.

  19. Interstellar Antifreeze: Ethylene Glycol

    NASA Technical Reports Server (NTRS)

    Hollis, J. M.; Lovas, F. J.; Jewell, P. R.; Coudert, L. H.

    2002-01-01

    Interstellar ethylene glycol (HOCH2CH2,OH) has been detected in emission toward the Galactic center source Sagittarius B2(N-LMH) by means of several millimeter-wave rotational torsional transitions of its lowest energy conformer. The types and kinds of molecules found to date in interstellar clouds suggest a chemistry that favors aldehydes and their corresponding reduced alcohols-e.g., formaldehyde (H2CO)/methanol (CH3OH), acetaldehyde (CH3CHO)/ethanol (CH3CH2OH). Similarly, ethylene glycol is the reduced alcohol of glycolaldehyde (CH2OHCHO), which has also been detected toward Sgr B2(N-LMH). While there is no consensus as to how any such large complex molecules are formed in the interstellar clouds, atomic hydrogen (H) and carbon monoxide (CO) could form formaldehyde on grain surfaces, but such surface chemistry beyond that point is uncertain. However, laboratory experiments have shown that the gas-phase reaction of atomic hydrogen (H) and solid-phase CO at 10-20 K can produce formaldehyde and methanol and that alcohols and other complex molecules can be synthesized from cometary ice analogs when subject to ionizing radiation at 15 K. Thus, the presence of aldehyde/ reduced alcohol pairs in interstellar clouds implies that such molecules are a product of a low-temperature chemistry on grain surfaces or in grain ice mantles. This work suggests that aldehydes and their corresponding reduced alcohols provide unique observational constraints on the formation of complex interstellar molecules.

  20. Glycolic acid production in the engineered yeasts Saccharomyces cerevisiae and Kluyveromyces lactis

    PubMed Central

    2013-01-01

    Background Glycolic acid is a C2 hydroxy acid that is a widely used chemical compound. It can be polymerised to produce biodegradable polymers with excellent gas barrier properties. Currently, glycolic acid is produced in a chemical process using fossil resources and toxic chemicals. Biotechnological production of glycolic acid using renewable resources is a desirable alternative. Results The yeasts Saccharomyces cerevisiae and Kluyveromyces lactis are suitable organisms for glycolic acid production since they are acid tolerant and can grow in the presence of up to 50 g l-1 glycolic acid. We engineered S. cerevisiae and K. lactis for glycolic acid production using the reactions of the glyoxylate cycle to produce glyoxylic acid and then reducing it to glycolic acid. The expression of a high affinity glyoxylate reductase alone already led to glycolic acid production. The production was further improved by deleting genes encoding malate synthase and the cytosolic form of isocitrate dehydrogenase. The engineered S. cerevisiae strain produced up to about 1 g l-1 of glycolic acid in a medium containing d-xylose and ethanol. Similar modifications in K. lactis resulted in a much higher glycolic acid titer. In a bioreactor cultivation with d-xylose and ethanol up to 15 g l-1 of glycolic acid was obtained. Conclusions This is the first demonstration of engineering yeast to produce glycolic acid. Prior to this work glycolic acid production through the glyoxylate cycle has only been reported in bacteria. The benefit of a yeast host is the possibility for glycolic acid production also at low pH, which was demonstrated in flask cultivations. Production of glycolic acid was first shown in S. cerevisiae. To test whether a Crabtree negative yeast would be better suited for glycolic acid production we engineered K. lactis in the same way and demonstrated it to be a better host for glycolic acid production. PMID:24053654

  1. Bacterial Utilization of Ether Glycols

    PubMed Central

    Fincher, Edward L.; Payne, W. J.

    1962-01-01

    A soil bacterium capable of using oligo- and polyethylene glycols and ether alcohols as sole sources of carbon for aerobic growth was isolated. The effects of substituent groups added to the ether bonds on the acceptability of the compounds as substrates were studied. Mechanisms for the incorporation of two-carbon compounds were demonstrated by the observation that acetate, glyoxylate, ethylene glycol, and a number of the tricarboxylic acid cycle intermediates served as growth substrates in minimal media. The rate of oxidation of the short-chained ethylene glycols by adapted resting cells varied directly with increasing numbers of two-carbon units in the chains from one to four. The amount of oxygen consumed per carbon atom of oligo- and polyethylene glycols was 100% of theoretical, but only 67% of theoretical for ethylene glycol. Resting cells oxidized oligo- and polyethylene glycols with 2 to 600 two-carbon units in the chains. Longer chained polyethylene glycols (up to 6,000) were oxidized at a very slow rate by these cells. Dehydrogenation of triethylene glycol by adapted cells was observed, coupling the reaction with methylene blue reduction. PMID:13945208

  2. Biodegradation of Ethylene Glycol by a Salt-Requiring Bacterium1

    PubMed Central

    Gonzalez, Carlos F.; Taber, Willard A.; Zeitoun, M. A.

    1972-01-01

    A gram-negative nonmotile rod which was capable of using 1,2-14C-ethylene glycol as a sole carbon source for growth was isolated from a brine pond, Great Salt Lake, Utah. The bacterium (ATCC 27042) required at least 0.85% NaCl for growth and, although the chloride ion was replaceable by sulfate ion, the sodium ion was not replaceable by potassium ion. The maximal concentration of salt tolerated for growth was approximately 12%. The bacterium was oxidase-negative when N,N-dimethyl-p-phenylenediamine was used and weakly positive when N,N,N′,N′-tetramethyl-p-phenylenediamine was used. It grows on many sugars but does not ferment them, it does not have an exogenous vitamin requirement, and it possesses a guanine plus cytosine ratio of 64.3%. Incorporation of ethylene glycol carbon into cell and respired CO2 was quantitated by use of radioactive ethylene glycol and a force-aerated fermentor. Glucose suppressed ethylene glycol metabolism. Cells grown on ethylene and propylene glycol respired ethylene glycol in a Warburg respirometer more rapidly than cells grown on glucose. Spectrophotometric evidence was obtained for oxidation of glycolate to glyoxylate by a dialyzed cell extract. PMID:4568254

  3. Simulated Waste Testing Of Glycolate Impacts On The 2H-Evaporator System

    SciTech Connect

    Martino, C. J.

    2013-08-13

    Glycolic acid is being studied as a total or partial replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste tank farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the tank farm were addressed via a literature review, but several outstanding issues remained. This report documents the non-radioactive simulant tests impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The testing for which non-radioactive simulants could be used involved the following: the partitioning of glycolate into the evaporator condensate, the impacts of glycolate on metal solubility, and the impacts of glycolate on the formation and dissolution of sodium aluminosilicate scale within the evaporator. The following are among the conclusions from this work: Evaporator condensate did not contain appreciable amounts of glycolate anion. Of all tests, the highest glycolate concentration in the evaporator condensate was 0.38 mg/L. A significant portion of the tests had glycolate concentration in the condensate at less than the limit of quantification (0.1 mg/L). At ambient conditions, evaporator testing did not show significant effects of glycolate on the soluble components in the evaporator concentrates. Testing with sodalite solids and silicon containing solutions did not show significant effects of glycolate on sodium aluminosilicate formation or dissolution.

  4. Symbiotic Burkholderia Species Show Diverse Arrangements of nif/fix and nod Genes and Lack Typical High-Affinity Cytochrome cbb3 Oxidase Genes.

    PubMed

    De Meyer, Sofie E; Briscoe, Leah; Martínez-Hidalgo, Pilar; Agapakis, Christina M; de-Los Santos, Paulina Estrada; Seshadri, Rekha; Reeve, Wayne; Weinstock, George; O'Hara, Graham; Howieson, John G; Hirsch, Ann M

    2016-08-01

    Genome analysis of fourteen mimosoid and four papilionoid beta-rhizobia together with fourteen reference alpha-rhizobia for both nodulation (nod) and nitrogen-fixing (nif/fix) genes has shown phylogenetic congruence between 16S rRNA/MLSA (combined 16S rRNA gene sequencing and multilocus sequence analysis) and nif/fix genes, indicating a free-living diazotrophic ancestry of the beta-rhizobia. However, deeper genomic analysis revealed a complex symbiosis acquisition history in the beta-rhizobia that clearly separates the mimosoid and papilionoid nodulating groups. Mimosoid-nodulating beta-rhizobia have nod genes tightly clustered in the nodBCIJHASU operon, whereas papilionoid-nodulating Burkholderia have nodUSDABC and nodIJ genes, although their arrangement is not canonical because the nod genes are subdivided by the insertion of nif and other genes. Furthermore, the papilionoid Burkholderia spp. contain duplications of several nod and nif genes. The Burkholderia nifHDKEN and fixABC genes are very closely related to those found in free-living diazotrophs. In contrast, nifA is highly divergent between both groups, but the papilionoid species nifA is more similar to alpha-rhizobia nifA than to other groups. Surprisingly, for all Burkholderia, the fixNOQP and fixGHIS genes required for cbb3 cytochrome oxidase production and assembly are missing. In contrast, symbiotic Cupriavidus strains have fixNOQPGHIS genes, revealing a divergence in the evolution of two distinct electron transport chains required for nitrogen fixation within the beta-rhizobia. PMID:27269511

  5. A high-performance liquid chromatography assay with a triazole-bonded column for evaluation of d-amino acid oxidase activity.

    PubMed

    Iwasaki, Megumi; Kashiwaguma, Yoshiyuki; Nagashima, Chihiro; Izumi, Mao; Uekusa, Ayano; Iwasa, Sumiko; Onozato, Mayu; Ichiba, Hideaki; Fukushima, Takeshi

    2016-03-01

    Elution profiles of kynurenic acid (KYNA) and 7-chlorokynurenic acid (Cl-KYNA) were examined by high-performance liquid chromatography (HPLC) using a triazole-bonded stationary phase column (Cosmosil® HILIC) under isocratic elution of a mobile phase consisting of CH3 CN-aqueous 10 mm ammonium formate between pH 3.0 and 6.0. The capacity factors of KYNA and Cl-KYNA varied with both the CH3 CN content and the pH of the mobile phase. The elution order of KYNA and Cl-KYNA was reversed between the CH3 CN- and H2 O-rich mobile phases, suggesting that hydrophilic interactions and anion-exchange interactions caused retention of KYNA and Cl-KYNA in the CH3 CN- and H2 O-rich mobile phases, respectively. The present HPLC method using a triazole-bonded column and fluorescence detection (excitation 250 nm, emission 398 nm) was applied to monitor in vitro production of KYNA from d-kynurenine (d-KYN) by d-amino acid oxidase (DAO) using Cl-KYNA as an internal standard. A single KYNA peak was clearly observed after enzymatic reaction of d-KYN with DAO. Production of KYNA from d-KYN was suppressed by the addition of commercial DAO inhibitors. The present HPLC method can be used to evaluate DAO activity and DAO inhibitory effects in candidate drugs for the treatment of schizophrenia. PMID:26174062

  6. Synthesis of ({sup 11}C) RO 19 6327, a highly selective and reversible monoamine oxidase B inhibitor potentially useful for treatment of Parkinson`s disease

    SciTech Connect

    Ding, Y.S.; Rehder, K.; Vassello, M.

    1994-05-01

    The potential neuroprotective effect of monoamine oxidase B (MAO B) inhibitors has stimulated intense interest in characterizing their modes of action and in developing new MAO B inhibitor drugs with different properties for clinical investigation in Parkinson`s disease and other enurodegenerative diseases. One of these drugs is Ro 19 6327 (N-(2-aminoethyl)-5-chloro-2-pyridine carboxamide {center_dot}HCl). Ro 19 6327 differs from the suicide inhibitor L-deprenyl in that it is more specific, greater than twenty times as potent in inhibiting MAO B, has no amphetamine metabolites, and is reversible. The recovery of MAO B activity 36 hours after Ro19 6327 treatment discontinuation is relevant in clinical studies since treatment can be withdrawn and changed without the complication of long term effects, as is seen with L-deprenyl. We report here a new synthetic approach to the precursor for Ro 19 6327 suitable for subsequent C-11 labeling for PET studies. Homolytic amidation of 3-chloropyridine afforded 5-chlor-2-pyridinecarboxamide which upon treatment with formaldehyde yielded 5-chlor-N-(hydroxymethyl)-2-pyridinecarboxamide. Conversion to the corresponding acetate afforded a substrate for the displacement reaction with ({sup 11}C) cyanide. Finding a highly selective reducing reagent for the following reduction step was crucial due t;o the presence of four reducible functional groups within the molecule, namely chlorine, pyridine ring, amide, and nitrile. Sodium borohydride in the presence of aluminum chloride was by far the most effective reagent. The final product was then purified by HPLC. The pharmacokinetics, regional distribution and metabolism of ({sup 11}C)Ro 19 6317 are currently under investigation with PET.

  7. A rapid analysis of plasma/serum ethylene and propylene glycol by headspace gas chromatography.

    PubMed

    Ehlers, Alexandra; Morris, Cory; Krasowski, Matthew D

    2013-12-01

    A rapid headspace-gas chromatography (HS-GC) method was developed for the analysis of ethylene glycol and propylene glycol in plasma and serum specimens using 1,3-propanediol as the internal standard. The method employed a single-step derivitization using phenylboronic acid, was linear to 200 mg/dL and had a lower limit of quantitation of 1 mg/dL suitable for clinical analyses. The analytical method described allows for laboratories with HS-GC instrumentation to analyze ethanol, methanol, isopropanol, ethylene glycol, and propylene glycol on a single instrument with rapid switch-over from alcohols to glycols analysis. In addition to the novel HS-GC method, a retrospective analysis of patient specimens containing ethylene glycol and propylene glycol was also described. A total of 36 patients ingested ethylene glycol, including 3 patients who presented with two separate admissions for ethylene glycol toxicity. Laboratory studies on presentation to hospital for these patients showed both osmolal and anion gap in 13 patients, osmolal but not anion gap in 13 patients, anion but not osmolal gap in 8 patients, and 1 patient with neither an osmolal nor anion gap. Acidosis on arterial blood gas was present in 13 cases. Only one fatality was seen; this was a patient with initial serum ethylene glycol concentration of 1282 mg/dL who died on third day of hospitalization. Propylene glycol was common in patients being managed for toxic ingestions, and was often attributed to iatrogenic administration of propylene glycol-containing medications such as activated charcoal and intravenous lorazepam. In six patients, propylene glycol contributed to an abnormally high osmolal gap. The common presence of propylene glycol in hospitalized patients emphasizes the importance of being able to identify both ethylene glycol and propylene glycol by chromatographic methods. PMID:23741644

  8. The effect of high polyphenol oxidase grass silage on metabolism of polyunsaturated fatty acids and nitrogen across the rumen of beef steers.

    PubMed

    Lee, M R F; Theobald, V J; Gordon, N; Leyland, M; Tweed, J K S; Fychan, R; Scollan, N D

    2014-11-01

    Polyphenol oxidase (PPO) activity in red clover (Trifolium pratense) has been reported to reduce both proteolysis and lipolysis, resulting in greater N use efficiency and protection of PUFA across the rumen. Although high levels of PPO have been reported in grasses such as cocksfoot (orchard grass; Dactylis glomerata), no in vivo research has determined whether grass PPO elicits the same response as red clover PPO. To test the hypothesis that silage ensiled from grass with high levels of PPO protects N and PUFA across the rumen, 6 steers with ruminal and duodenal cannulas were offered cocksfoot silage (CO; high-PPO grass), perennial ryegrass silage (PR; Lolium perenne; low-PPO grass), or red clover silage (RC; high-PPO control) at 16 g DM/kg BW daily with the experiment consisting of two 3 × 3 Latin squares with 21-d periods, consisting of 12 d of diet adaptation, 6 d of duodenal marker infusion, 2 d of duodenal sampling, and 1 d of ruminal sampling. All silages were well preserved, with DM of 34.4, 55.3, and 45.4% for CO, PR, and RC. Activity of PPO in silages was low due to deactivation but was greater in CO than either PR or RC (0.15 vs. 0.05 and 0.08 μkatal/g DM). Protein-bound phenol (mg/g DM) as a measure of the degree of oxidation and an indication of PPO protection was greatest for RC (15.9) but comparable for PR (10.1) and CO (12.2). Biohydrogenation of C18 PUFA was significantly lower on RC compared to the 2 grass silages with CO greater than PR. Despite lower levels of total fatty acid intake and subsequent duodenal flow, CO resulted in greater levels of phytanic acid and total branched and odd chain fatty acids in duodenal digesta than RC or PR. Ruminal ammonia concentration was greatest for RC, with no difference between the grasses. Duodenal flow of microbial N and efficiency of microbial protein synthesis were lowest for CO and comparable for RC and PR. The CO (high-grass PPO) did not result in elevated levels of C18 PUFA escaping the rumen or

  9. Oxidative stress, NADPH oxidases, and arteries.

    PubMed

    Sun, Qi-An; Runge, Marschall S; Madamanchi, Nageswara R

    2016-05-10

    Atherosclerosis and its major complications - myocardial infarction and stroke - remain major causes of death and disability in the United States and world-wide. Indeed, with dramatic increases in obesity and diabetes mellitus, the prevalence and public health impact of cardiovascular diseases (CVD) will likely remain high. Major advances have been made in development of new therapies to reduce the incidence of atherosclerosis and CVD, in particular for treatment of hypercholesterolemia and hypertension. Oxidative stress is the common mechanistic link for many CVD risk factors. However, only recently have the tools existed to study the interface between oxidative stress and CVD in animal models. The most important source of reactive oxygen species (and hence oxidative stress) in vascular cells are the multiple forms of enzymes nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase). Recently published and emerging studies now clearly establish that: 1) NADPH oxidases are of critical importance in atherosclerosis and hypertension in animal models; 2) given the tissue-specific expression of key components of NADPH oxidase, it may be possible to target vascular oxidative stress for prevention of CVD. PMID:25649240

  10. Concentration of Nicotine and Glycols in 27 Electronic Cigarette Formulations.

    PubMed

    Peace, Michelle R; Baird, Tyson R; Smith, Nathaniel; Wolf, Carl E; Poklis, Justin L; Poklis, Alphonse

    2016-07-01

    Personal battery-powered vaporizers or electronic cigarettes were developed to deliver a nicotine vapor such that smokers could simulate smoking tobacco without the inherent pathology of inhaled tobacco smoke. Electronic cigarettes and their e-cigarette liquid formulations are virtually unregulated. These formulations are typically composed of propylene glycol and/or glycerin, flavoring components and an active drug, such as nicotine. Twenty-seven e-cigarette liquid formulations that contain nicotine between 6 and 22 mg/L were acquired within the USA and analyzed by various methods to determine their contents. They were screened by Direct Analysis in Real Time™ Mass Spectrometry (DART-MS). Nicotine was confirmed and quantitated by high-performance liquid chromatography-tandem mass spectrometry, and the glycol composition was confirmed and quantitated by gas chromatography-mass spectrometry. The DART-MS screening method was able to consistently identify the exact mass peaks resulting from the protonated molecular ion of nicotine, glycol and a number of flavor additives within 5 mmu. Nicotine concentrations were determined to range from 45 to 131% of the stated label concentration, with 18 of the 27 have >10% variance. Glycol composition was generally accurate to the product description, with only one exception where the propylene glycol to glycerin percentage ratio was stated as 50:50 and the determined concentration of propylene glycol to glycerin was 81:19 (% v/v). No unlabeled glycols were detected in these formulations. PMID:27165804

  11. Crystallization of Mitochondrial Cytochrome Oxidase

    NASA Astrophysics Data System (ADS)

    Ozawa, Takayuki; Tanaka, Masashi; Wakabayashi, Takashi

    1982-12-01

    Cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) was purified from beef heart mitochondria. By washing the oxidase with detergent on a hydrophobic interaction column, phospholipids were depleted to the level of 1 mol of cardiolipin per mol of heme a. Hydrophobic impurities and partially denatured oxidase were separated from the intact oxidase on an affinity column with cytochrome c as the specific ligand. The final preparation of the oxidase contained seven distinct polypeptides. The molecular weight of the oxidase was estimated to be 130,000 from its specific heme a and copper content and from the subunit composition. Crystals of the oxidase were obtained by slow removal of the detergent from the buffer in which the oxidase was dissolved. The needle-shaped crystals were 100 μ m in average length and 5 μ m in width, and they strongly polarized visible light. Electron diffraction patterns were obtained with an unstained glutaraldehyde-fixed single crystal by electron microscopy using 1,000-kV electrons. From electron micrographs and the diffraction patterns of the crystal, it was concluded that the crystal is monoclinic in the space group P21, with unit cell dimensions a = 92 angstrom, b = 84 angstrom, and c = 103 angstrom, and α =β 90 degrees, γ = 126 degrees.

  12. A Density Functional Study for the Bridged Dinuclear Center Based on a High Resolution X-ray Crystal Structure of ba3 Cytochrome c Oxidase from Thermus thermophilus

    PubMed Central

    Du, Wen-Ge Han; Noodleman, Louis

    2014-01-01

    Strong electron density for a peroxide type dioxygen species bridging the Fea3 and CuB dinuclear center (DNC) was observed in the high resolution (1.8 Å) X-ray crystal structures (PDB entries: 3S8G and 3S8F) of ba3 cytochrome c oxidase (CcO) from Thermus thermophilus (Tiefenbrunn et al. PLos ONE 2011, 7, e22348). The crystals represent the as-isolated X-ray photoreduced CcO structures. The bridging peroxide was proposed to arise from the recombination of two radiation produced HO· radicals formed either very near to or even in the space between the two metals of the DNC. It is unclear whether this peroxide species is in the O22−, O2·−, HO2−, or in the H2O2 form, and what is the detailed electronic structure and binding geometry including the DNC. In order to answer what form of this dioxygen species was observed in the DNC of the 1.8 Å X-ray CcO crystal structure (3S8G), we have applied broken-symmetry density functional theory (BS-DFT) geometric and energetic calculations (using OLYP potential) on large DNC cluster models with different Fea3-CuB oxidation and spin states and with either O22−, O2·−, HO2−, or H2O2 in the bridging position. By comparing the DFT optimized geometries with the X-ray crystal structure (3S8G), we propose that the bridging peroxide is HO2−. The X-ray crystal structure is likely to represent the superposition of the Fea32+-(HO2−)-CuB1+ DNC’s in different states (Fe2+ in low-spin (LS), intermediate-spin (IS), or high-spin (HS)) with the majority species having the proton of the HO2− residing on the oxygen atom (O1) which is closer to the Fea32+ site in the Fea32+-(HO-O)−-CuB1+ conformation. Our calculations show that the sidechain of Tyr237 is likely trapped in the deprotonated Tyr237− anion form in the 3S8G X-ray crystal structure. PMID:24262070

  13. A Phase IIb, Multicenter, Open-Label, Safety, and Efficacy Study of High-Dose, Propylene Glycol-Free Melphalan Hydrochloride for Injection (EVOMELA) for Myeloablative Conditioning in Multiple Myeloma Patients Undergoing Autologous Transplantation.

    PubMed

    Hari, Parameswaran; Aljitawi, Omar S; Arce-Lara, Carlos; Nath, Rajneesh; Callander, Natalie; Bhat, Gajanan; Allen, Lee F; Stockerl-Goldstein, Keith

    2015-12-01

    Autologous stem cell transplantation (ASCT) after high-dose melphalan conditioning is considered a standard of care procedure for patients with multiple myeloma (MM). Current formulations of melphalan (eg, Alkeran for Injection [melphalan hydrochloride]; GlaxoSmithKline, Research Triangle Park, NC, USA) have marginal solubility and limited chemical stability upon reconstitution. Alkeran requires the use of propylene glycol as a co-solvent, which itself has been reported to cause such complications as metabolic/renal dysfunction and arrhythmias. EVOMELA (propylene glycol-free melphalan HCl; Spectrum Pharmaceuticals, Inc., Irvine, CA, USA) is a new i.v. melphalan formulation that incorporates Captisol (Ligand Pharmaceuticals, Inc., La Jolla, CA, USA), a specially modified cyclodextrin that improves the solubility and stability of melphalan and eliminates the need for propylene glycol. This new formulation has been shown to be bioequivalent to Alkeran. EVOMELA (200 mg/m(2)) was administered as 2 doses of 100 mg/m(2) each in a phase IIb, open-label, multicenter study to confirm its safety and efficacy as a high-dose conditioning regimen for patients with MM undergoing ASCT. At 5 centers, 61 patients (26 women) with a median age of 62 years (range, 32-73) were enrolled. All patients achieved myeloablation with a median time of 5 days post-ASCT, and all successfully achieved neutrophil and platelet engraftment with median times of 12 days post-ASCT and 13 days post-ASCT, respectively; treatment-related mortality on day 100 was 0%. Overall response rate (according to independent, blinded review) was high (100%), with an overall complete response rate of 21% (13% stringent complete response; 8% complete response) and overall partial response rate of 79% (61% very good partial response; 18% partial response). The incidence of grade 3 mucositis and stomatitis was low (10% and 5%, respectively) with no grade 4 mucositis or stomatitis reported (graded according to National

  14. An oxidase-based electrochemical fluidic sensor with high-sensitivity and low-interference by on-chip oxygen manipulation.

    PubMed

    Radhakrishnan, Nitin; Park, Jongwon; Kim, Chang-Soo

    2012-01-01

    Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide). Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc.) to implement a viable component for in-line fluidic sensor systems. PMID:23012527

  15. Absorption of some glycol ethers through human skin in vitro.

    PubMed Central

    Dugard, P H; Walker, M; Mawdsley, S J; Scott, R C

    1984-01-01

    To assist evaluation of the hazards of skin contact with selected undiluted glycol ethers, their absorption across isolated human abdominal epidermis was measured in vitro. Epidermal membranes were set up in glass diffusion cells and, following an initial determination of permeability to tritiated water, excess undiluted glycol ether was applied to the outer surface for 8 hr. The appearance of glycol ether in an aqueous "receptor" phase bathing the underside of the epidermis was quantified by a gas chromatographic technique. A final determination of tritiated water permeability was compared with initial values to establish any irreversible alterations in epidermal barrier function induced by contact with the glycol ethers. 2-methoxyethanol (EM) was most readily absorbed (mean steady rate 2.82 mg/cm2/hr), and a relatively high absorption rate (1.17 mg/cm2/hr) was also apparent for 1-methoxypropan-2-ol (PM). There was a trend of reducing absorption rate with increasing molecular weight or reducing volatility for monoethylene glycol ethers (EM, 2.82 mg/cm2/hr; 2-ethoxyethanol, EE, 0.796 mg/cm2/hr; 2-butoxyethanol, EB, 0.198 mg/cm2/hr) and also within the diethylene glycol series: 2-(2-methoxyethoxy) ethanol (DM, 0.206 mg/cm2/hr); 2-(2-ethoxyethoxy) ethanol (DE, 0.125 mg/cm2/hr) and 2-(2-butoxyethoxy) ethanol (DB, 0.035 mg/cm2/hr). The rate of absorption of 2-ethoxyethyl acetate (EEAc) was similar to that of the parent alcohol, EE. Absorption rates of diethylene glycol ethers were slower than their corresponding monoethylene glycol equivalents. Combination of intrinsic toxicity and ability to pass across skin contribute to assessment of hazards of contact with undiluted glycol ethers. PMID:6499804

  16. Photorespiratory glycolate-glyoxylate metabolism.

    PubMed

    Dellero, Younès; Jossier, Mathieu; Schmitz, Jessica; Maurino, Veronica G; Hodges, Michael

    2016-05-01

    Photorespiration is one of the major carbon metabolism pathways in oxygen-producing photosynthetic organisms. This pathway recycles 2-phosphoglycolate (2-PG), a toxic metabolite, to 3-phosphoglycerate when ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) uses oxygen instead of carbon dioxide. The photorespiratory cycle is in competition with photosynthetic CO2 fixation and it is accompanied by carbon, nitrogen and energy losses. Thus, photorespiration has become a target to improve crop yields. Moreover, during the photorespiratory cycle intermediate metabolites that are toxic to Calvin-Benson cycle and RuBisCO activities, such as 2-PG, glycolate and glyoxylate, are produced. Thus, the presence of an efficient 2-PG/glycolate/glyoxylate 'detoxification' pathway is required to ensure normal development of photosynthetic organisms. Here we review our current knowledge concerning the enzymes that carry out the glycolate-glyoxylate metabolic steps of photorespiration from glycolate production in the chloroplasts to the synthesis of glycine in the peroxisomes. We describe the properties of the proteins involved in glycolate-glyoxylate metabolism in Archaeplastida and the phenotypes observed when knocking down/out these specific photorespiratory players. Advances in our understanding of the regulation of glycolate-glyoxylate metabolism are highlighted. PMID:26994478

  17. Evaluation of oxalate decarboxylase and oxalate oxidase for industrial applications.

    PubMed

    Cassland, Pierre; Sjöde, Anders; Winestrand, Sandra; Jönsson, Leif J; Nilvebrant, Nils-Olof

    2010-05-01

    Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching. PMID:19763895

  18. Synthesis of glycolate from pyruvate via isocitrate lyase by tobacco leaves in light. [Nicotiana tabacum var Havana Seed

    SciTech Connect

    Zelitch, I. )

    1988-02-01

    Tobacco (Nicotiana tabacum var Havana Seed) leaf discs were supplied tracer quantities of (2-{sup 14}C)- and (3-{sup 14}C) pyruvate for 60 minutes in steady state photosynthesis with 21% or 1% O{sub 2}, and the glycolate oxidase inhibitor {alpha}-hydroxy-2-pyridinemethanesulfonic acid was then added for 5 or 10 minutes to cause glycolate to accumulate. The (3-{sup 14}C) pyruvate was converted directly to glycolate as shown by a 50% greater than equal-labeled {sup 14}C in C-2 of glycolate, and the fraction of {sup 14}C in C-2 increased in 1% O{sub 2} to 80% greater than equal-labeled. This suggests the pathway using pyruvate is less O{sub 2}-dependent than the oxygenase reaction producing glycolate from the Calvin cycle. The formation of glycolate from pyruvate in the leaf discs was time-dependent and with (2-{sup 14}C)- and (3-{sup 14}C) pyruvate supplied leaf discs the C-2 of glyoxylate derived from C-2 of isocitrate was labeled asymmetrically in a manner similar to the asymmetrical labeling of C-2 of glycolate under a number of conditions. Thus glycolate was probably formed by the reduction of glyoxylate. Isocitric lyase activity of tobacco leaves was associated with leaf mitochondria, through most of the activity was in the supernatant fraction after differential centrifugation of leaf homogenates.

  19. Expression of terminal oxidases under nutrient-starved conditions in Shewanella oneidensis: detection of the A-type cytochrome c oxidase

    PubMed Central

    Le Laz, Sébastien; kpebe, Arlette; Bauzan, Marielle; Lignon, Sabrina; Rousset, Marc; Brugna, Myriam

    2016-01-01

    Shewanella species are facultative anaerobic bacteria that colonize redox-stratified habitats where O2 and nutrient concentrations fluctuate. The model species Shewanella oneidensis MR-1 possesses genes coding for three terminal oxidases that can perform O2 respiration: a bd-type quinol oxidase and cytochrome c oxidases of the cbb3-type and the A-type. Whereas the bd- and cbb3-type oxidases are routinely detected, evidence for the expression of the A-type enzyme has so far been lacking. Here, we investigated the effect of nutrient starvation on the expression of these terminal oxidases under different O2 tensions. Our results reveal that the bd-type oxidase plays a significant role under nutrient starvation in aerobic conditions. The expression of the cbb3-type oxidase is also modulated by the nutrient composition of the medium and increases especially under iron-deficiency in exponentially growing cells. Most importantly, under conditions of carbon depletion, high O2 and stationary-growth, we report for the first time the expression of the A-type oxidase in S. oneidensis, indicating that this terminal oxidase is not functionally lost. The physiological role of the A-type oxidase in energy conservation and in the adaptation of S. oneidensis to redox-stratified environments is discussed. PMID:26815910

  20. Expression of terminal oxidases under nutrient-starved conditions in Shewanella oneidensis: detection of the A-type cytochrome c oxidase.

    PubMed

    Le Laz, Sébastien; Kpebe, Arlette; Bauzan, Marielle; Lignon, Sabrina; Rousset, Marc; Brugna, Myriam

    2016-01-01

    Shewanella species are facultative anaerobic bacteria that colonize redox-stratified habitats where O2 and nutrient concentrations fluctuate. The model species Shewanella oneidensis MR-1 possesses genes coding for three terminal oxidases that can perform O2 respiration: a bd-type quinol oxidase and cytochrome c oxidases of the cbb3-type and the A-type. Whereas the bd- and cbb3-type oxidases are routinely detected, evidence for the expression of the A-type enzyme has so far been lacking. Here, we investigated the effect of nutrient starvation on the expression of these terminal oxidases under different O2 tensions. Our results reveal that the bd-type oxidase plays a significant role under nutrient starvation in aerobic conditions. The expression of the cbb3-type oxidase is also modulated by the nutrient composition of the medium and increases especially under iron-deficiency in exponentially growing cells. Most importantly, under conditions of carbon depletion, high O2 and stationary-growth, we report for the first time the expression of the A-type oxidase in S. oneidensis, indicating that this terminal oxidase is not functionally lost. The physiological role of the A-type oxidase in energy conservation and in the adaptation of S. oneidensis to redox-stratified environments is discussed. PMID:26815910

  1. Dielectric secondary relaxations in polypropylene glycols.

    PubMed

    Grzybowska, K; Grzybowski, A; Zioło, J; Paluch, M; Capaccioli, S

    2006-07-28

    Broadband dielectric measurements of polypropylene glycol of molecular weight M(w)=400 g / mol (PPG 400) were carried out at ambient pressure over the wide temperature range from 123 to 353 K. Three relaxation processes were observed. Besides the structural alpha relaxation, two secondary relaxations, beta and gamma, were found. The beta process was identified as the true Johari-Goldstein relaxation by using a criterion based on the coupling model prediction. The faster gamma relaxation, well separated from the primary process, undoubtedly exhibits the anomalous behavior near the glass transition temperature (T(g)) which is reflected in the presence of a minimum of the temperature dependence of the gamma-relaxation time. We successfully applied the minimal model [Dyre and Olsen, Phys. Rev. Lett. 91, 155703 (2003)] to describe the entire temperature dependence of the gamma-relaxation time. The asymmetric double-well potential parameters obtained by Dyre and Olsen for the secondary relaxation of tripropylene glycol at ambient pressure were modified by fitting to the minimal model at lower temperatures. Moreover, we showed that the effect of the molecular weight of polypropylene glycol on the minimal model parameters is significantly larger than that of the high pressure. Such results can be explained by the smaller degree of hydrogen bonds formed by longer chain molecules of PPG at ambient pressure than that created by shorter chains of PPG at high pressure. PMID:16942189

  2. NADPH Oxidase and Neurodegeneration

    PubMed Central

    Hernandes, Marina S; Britto, Luiz R G

    2012-01-01

    NADPH oxidase (Nox) is a unique, multi-protein, electron transport system that produces large amounts of superoxide via the reduction of molecular oxygen. Nox-derived reactive oxygen species (ROS) are known to be involved in a variety of physiological processes, including host defense and signal transduction. However, over the past decade, the involvement of (Nox)-dependent oxidative stress in the pathophysiology of several neurodegenerative diseases has been increasingly recognized. ROS produced by Nox proteins contribute to neurodegenerative diseases through distinct mechanisms, such as oxidation of DNA, proteins, lipids, amino acids and metals, in addition to activation of redox-sensitive signaling pathways. In this review, we discuss the recent literature on Nox involvement in neurodegeneration, focusing on Parkinson and Alzheimer diseases. PMID:23730256

  3. Preparation and electrochemical properties of gel polymer electrolytes using triethylene glycol diacetate-2-propenoic acid butyl ester copolymer for high energy density lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Fan, Huanhuan; Li, Hongxiao; Fan, Li-Zhen; Shi, Qiao

    2014-03-01

    Gel polymer electrolytes (GPE) composed of triethylene glycol diacetate (TEGDA)-2-propenoic acid butyl ester (BA) copolymer and commercial used liquid organic electrolyte are prepared via in situ polymerization. The ionic conductivity of the as-prepared GPE can reach 5.5 × 10-3 S cm-1 with 6 wt% monomers and 94 wt% liquid electrolyte at 25 °C. Additionally, the temperature dependence of the ionic conductivity is consistent with an Arrhenius temperature behavior in a temperature range of 20-90 °C. Furthermore, the electrochemical stability window of the GPE is 5 V at 25 °C. A Li|GPE|(Li[Li1/6Ni1/4Mn7/12]O2) cell has been fabricated, which shows good charge-discharge properties and stable cycle performance compared to liquid electrolyte under the same test conditions.

  4. Glycolic acid peel therapy - a current review.

    PubMed

    Sharad, Jaishree

    2013-01-01

    Chemical peels have been time-tested and are here to stay. Alpha-hydroxy peels are highly popular in the dermatologist's arsenal of procedures. Glycolic acid peel is the most common alpha-hydroxy acid peel, also known as fruit peel. It is simple, inexpensive, and has no downtime. This review talks about various studies of glycolic acid peels for various indications, such as acne, acne scars, melasma, postinflammatory hyperpigmentation, photoaging, and seborrhea. Combination therapies and treatment procedure are also discussed. Careful review of medical history, examination of the skin, and pre-peel priming of skin are important before every peel. Proper patient selection, peel timing, and neutralization on-time will ensure good results, with no side effects. Depth of the glycolic acid peel depends on the concentration of the acid used, the number of coats applied, and the time for which it is applied. Hence, it can be used as a very superficial peel, or even a medium depth peel. It has been found to be very safe with Fitzpatrick skin types I-IV. All in all, it is a peel that is here to stay. PMID:24399880

  5. High temperature proton exchange membranes with enhanced proton conductivities at low humidity and high temperature based on polymer blends and block copolymers of poly(1,3-cyclohexadiene) and poly(ethylene glycol)

    SciTech Connect

    Deng, Shawn; Hassan, Mohammad K.; Nalawade, Amol; Perry, Kelly A.; More, Karren L.; Mauritz, Kenneth A.; McDonnell, Marshall T.; Keffer, David J.; Mays, Jimmy W.

    2015-09-16

    Hot (at 120 °C) and dry (20% relative humidity) operating conditions benefit fuel cell designs based on proton exchange membranes (PEMs) and hydrogen due to simplified system design and increasing tolerance to fuel impurities. In this paper, presented are preparation, partial characterization, and multi-scale modeling of such PEMs based on cross-linked, sulfonated poly(1,3-cyclohexadiene) (xsPCHD) blends and block copolymers with poly(ethylene glycol) (PEG). These low cost materials have proton conductivities 18 times that of current industry standard Nafion at hot, dry operating conditions. Among the membranes studied, the blend xsPCHD-PEG PEM displayed the highest proton conductivity, which exhibits a morphology with higher connectivity of the hydrophilic domain throughout the membrane. Simulation and modeling provide a molecular level understanding of distribution of PEG within this hydrophilic domain and its relation to proton conductivities. Finally, this study demonstrates enhancement of proton conductivity at high temperature and low relative humidity by incorporation of PEG and optimized sulfonation conditions.

  6. High temperature proton exchange membranes with enhanced proton conductivities at low humidity and high temperature based on polymer blends and block copolymers of poly(1,3-cyclohexadiene) and poly(ethylene glycol)

    DOE PAGESBeta

    Deng, Shawn; Hassan, Mohammad K.; Nalawade, Amol; Perry, Kelly A.; More, Karren L.; Mauritz, Kenneth A.; McDonnell, Marshall T.; Keffer, David J.; Mays, Jimmy W.

    2015-09-16

    Hot (at 120 °C) and dry (20% relative humidity) operating conditions benefit fuel cell designs based on proton exchange membranes (PEMs) and hydrogen due to simplified system design and increasing tolerance to fuel impurities. In this paper, presented are preparation, partial characterization, and multi-scale modeling of such PEMs based on cross-linked, sulfonated poly(1,3-cyclohexadiene) (xsPCHD) blends and block copolymers with poly(ethylene glycol) (PEG). These low cost materials have proton conductivities 18 times that of current industry standard Nafion at hot, dry operating conditions. Among the membranes studied, the blend xsPCHD-PEG PEM displayed the highest proton conductivity, which exhibits a morphology withmore » higher connectivity of the hydrophilic domain throughout the membrane. Simulation and modeling provide a molecular level understanding of distribution of PEG within this hydrophilic domain and its relation to proton conductivities. Finally, this study demonstrates enhancement of proton conductivity at high temperature and low relative humidity by incorporation of PEG and optimized sulfonation conditions.« less

  7. Inhibition of plant and mammalian diamine oxidase by substrate analogues.

    PubMed

    Biegański, T; Osińska, Z; Masliński, C

    1982-04-01

    Imidazoles, aliphatic substrate analogues and the natural dipeptides, carnosine and anserine, were investigated as inhibitors of diamine oxidase from the pig kidney, human pregnancy plasma and pea seedlings. Imidazole, methylimidazoles, N-acetylimidazole, histamine and N tau-methylhistamine are relatively potent inhibitors of mammalian diamine oxidase showing no influence on plant enzymes. Anserine and carnosine are inhibitors of pig kidney and pea seedling enzymes. Ki values are 2 microM and 10 microM respectively. Investigated natural derivatives of putrescine and cadaverine have no influence on diamine oxidase of different origin. In conclusion, we present some evidence to suggest that mammalian diamine oxidase, despite a high reaction rate with putrescine, is better adapted to histamine oxidation, whereas for plant enzymes the diamines are preferred substrates. PMID:6805264

  8. Activation of Cytosolic Pyruvate Kinase by Polyethylene Glycol.

    PubMed Central

    Podesta, F. E.; Plaxton, W. C.

    1993-01-01

    Homogeneous cytosolic pyruvate kinase from endosperm of germinating castor oil (Ricinus communis L. cv Hale) seeds was potently activated by polyethylene glycol. The addition of 5% (w/v) polyethylene glycol to the pyruvate kinase reaction mixture caused a 2.6-fold increase in maximal velocity and 12.5- and 2-fold reductions in Km values for phosphoenolpyruvate and ADP, respectively. Glycerol, ethylene glycol, and bovine serum albumin also enhanced pyruvate kinase activity, albeit to a lesser extent than polyethylene glycol. The addition of 5% (w/v) polyethylene glycol to the elution buffer during high-performance gel filtration chromatography of purified cytosolic pyruvate kinase helped to stabilize the active heterotetrameric native structure of the enzyme. A higher degree of inhibition by MgATP, but lower sensitivity to the inhibitors 3-phosphoglycerate and fructose- 1,6-bisphosphate, was also observed in the presence of 5% (w/v) polyethylene glycol. It is concluded that (a) plant cytosolic pyruvate kinase activity and regulation, like that of other regulatory pyruvate kinases, is modified by extreme dilution in the assay medium, probably as a result of deaggregation of the native tetrameric enzyme, and (b) ATP is probably the major metabolic effector of germinating castor endosperm cytosolic pyruvate kinase in vivo. PMID:12231936

  9. Activation of Cytosolic Pyruvate Kinase by Polyethylene Glycol.

    PubMed

    Podesta, F. E.; Plaxton, W. C.

    1993-09-01

    Homogeneous cytosolic pyruvate kinase from endosperm of germinating castor oil (Ricinus communis L. cv Hale) seeds was potently activated by polyethylene glycol. The addition of 5% (w/v) polyethylene glycol to the pyruvate kinase reaction mixture caused a 2.6-fold increase in maximal velocity and 12.5- and 2-fold reductions in Km values for phosphoenolpyruvate and ADP, respectively. Glycerol, ethylene glycol, and bovine serum albumin also enhanced pyruvate kinase activity, albeit to a lesser extent than polyethylene glycol. The addition of 5% (w/v) polyethylene glycol to the elution buffer during high-performance gel filtration chromatography of purified cytosolic pyruvate kinase helped to stabilize the active heterotetrameric native structure of the enzyme. A higher degree of inhibition by MgATP, but lower sensitivity to the inhibitors 3-phosphoglycerate and fructose- 1,6-bisphosphate, was also observed in the presence of 5% (w/v) polyethylene glycol. It is concluded that (a) plant cytosolic pyruvate kinase activity and regulation, like that of other regulatory pyruvate kinases, is modified by extreme dilution in the assay medium, probably as a result of deaggregation of the native tetrameric enzyme, and (b) ATP is probably the major metabolic effector of germinating castor endosperm cytosolic pyruvate kinase in vivo. PMID:12231936

  10. Bactericidal activity of propylene glycol, glycerine, polyethylene glycol 400, and polyethylene glycol 1000 against selected microorganisms

    PubMed Central

    Nalawade, Triveni Mohan; Bhat, Kishore; Sogi, Suma H. P.

    2015-01-01

    Aim: The aim of the present study was to evaluate the bactericidal activity of propylene glycol, glycerine, polyethylene glycol 400 (PEG 400), and polyethylene glycol 1000 (PEG 1000) against selected microorganisms in vitro. Materials and Methods: Five vehicles, namely propylene glycol, glycerine, PEG 400, PEG 1000, and combination of propylene glycol with PEG 400, were tested for their bactericidal activity. The minimum bactericidal concentration was noted against four standard strains of organisms, i.e. Streptococcus mutans American Type Culture Collection (ATCC) 25175, Streptococcus mutans ATCC 12598, Enterococcus faecalis ATCC 35550, and Escherichia coli ATCC 25922, using broth dilution assay. Successful endodontic therapy depends upon thorough disinfection of root canals. In some refractory cases, routine endodontic therapy is not sufficient, so intracanal medicaments are used for proper disinfection of canals. Intracanal medicaments are dispensed with vehicles which aid in increased diffusion through the dentinal tubules and improve their efficacy. Among the various vehicles used, glycerine is easily available, whereas others like propylene glycol and polyethylene glycol have to be procured from appropriate sources. Also, these vehicles, being viscous, aid in sustained release of the medicaments and improve their handling properties. The most commonly used intracanal medicaments like calcium hydroxide are ineffective on many microorganisms, while most of the other medicaments like MTAD (Mixture of Tetracycline, an Acid, and a Detergent) and Triple Antibiotic Paste (TAP) consist of antibiotics which can lead to development of antibiotic resistance among microorganisms. Thus, in order to use safer and equally effective intracanal medicaments, newer alternatives like chlorhexidine gluconate, ozonized water, etc., are being explored. Similarly, the five vehicles mentioned above are being tested for their antimicrobial activity in this study. Results: All vehicles

  11. [Respiratory oxidases: the enzymes which use most of the oxygen which living things breathe].

    PubMed

    Toledo-Cuevas, E M

    1997-01-01

    The respiratory oxidases are the last enzymes of the aerobic respiratory chain. They catalize the reduction of molecular oxygen to water, with generation of an electrochemical gradient useful for the energy demanding cellular processes. Most of the oxidases belong to the heme-copper superfamily. They possess a heme-copper center, constituted of a high spin heme and a CuB center, where the reduction of oxygen takes place and probably where the link to proton pumping is located. The superfamily is divided in two classes: the quinol- and the cytochrome c-oxidases. The latter are divided in the aa3 and the cbb3-type cytochrome c oxidases. The main difference between quinol- and the aa3-type cytochrome c-oxidases is the CuA center, which is absent in the quinol oxidases. The cbb3-type cytochrome oxidases have the binuclear center, but lack the CuA center. They also does not have the classical subunits II and III. These differences seem not to affect the oxygen reduction or the proton pumping. Probably the oxidases have evolved from some denitrification enzymes and prior the photosynthetic process. Also is possible that the cbb3-type cytochrome oxidases or others very similar have been the first oxidases to appear. PMID:10932727

  12. Colorometric detection of ethylene glycol vapor

    NASA Technical Reports Server (NTRS)

    Helm, C.; Mosier, B.; Verostko, C. E.

    1970-01-01

    Very low concentrations of ethylene glycol in air or other gases are detected by passing a sample through a glass tube with three partitioned compartments containing reagents which successively convert the ethylene glycol vapor into a colored compound.

  13. The remarkable activity and stability of a highly dispersive beta-brass Cu-Zn catalyst for the production of ethylene glycol

    PubMed Central

    Li, Molly Meng-Jung; Zheng, Jianwei; Qu, Jin; Liao, Fenglin; Raine, Elizabeth; Kuo, Winson C. H.; Su, Shei Sia; Po, Pang; Yuan, Youzhu; Tsang, Shik Chi Edman

    2016-01-01

    Incorporation of Zn atoms into a nanosize Cu lattice is known to alter the electronic properties of Cu, improving catalytic performance in a number of industrially important reactions. However the structural influence of Zn on the Cu phase is not well studied. Here, we show that Cu nano-clusters modified with increasing concentration of Zn, derived from ZnO support doped with Ga3+, can dramatically enhance their stability against metal sintering. As a result, the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol, an important reaction well known for deactivation from copper nanoparticle sintering, can show greatly enhanced activity and stability with the CuZn alloy catalysts due to no noticeable sintering. HRTEM, nano-diffraction and EXAFS characterization reveal the presence of a small beta-brass CuZn alloy phase (body-centred cubic, bcc) which appears to greatly stabilise Cu atoms from aggregation in accelerated deactivation tests. DFT calculations also indicate that the small bcc CuZn phase is more stable against Cu adatom migration than the fcc CuZn phase with the ability to maintain a higher Cu dispersion on its surface. PMID:26856760

  14. The remarkable activity and stability of a highly dispersive beta-brass Cu-Zn catalyst for the production of ethylene glycol

    NASA Astrophysics Data System (ADS)

    Li, Molly Meng-Jung; Zheng, Jianwei; Qu, Jin; Liao, Fenglin; Raine, Elizabeth; Kuo, Winson C. H.; Su, Shei Sia; Po, Pang; Yuan, Youzhu; Tsang, Shik Chi Edman

    2016-02-01

    Incorporation of Zn atoms into a nanosize Cu lattice is known to alter the electronic properties of Cu, improving catalytic performance in a number of industrially important reactions. However the structural influence of Zn on the Cu phase is not well studied. Here, we show that Cu nano-clusters modified with increasing concentration of Zn, derived from ZnO support doped with Ga3+, can dramatically enhance their stability against metal sintering. As a result, the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol, an important reaction well known for deactivation from copper nanoparticle sintering, can show greatly enhanced activity and stability with the CuZn alloy catalysts due to no noticeable sintering. HRTEM, nano-diffraction and EXAFS characterization reveal the presence of a small beta-brass CuZn alloy phase (body-centred cubic, bcc) which appears to greatly stabilise Cu atoms from aggregation in accelerated deactivation tests. DFT calculations also indicate that the small bcc CuZn phase is more stable against Cu adatom migration than the fcc CuZn phase with the ability to maintain a higher Cu dispersion on its surface.

  15. The remarkable activity and stability of a highly dispersive beta-brass Cu-Zn catalyst for the production of ethylene glycol.

    PubMed

    Li, Molly Meng-Jung; Zheng, Jianwei; Qu, Jin; Liao, Fenglin; Raine, Elizabeth; Kuo, Winson C H; Su, Shei Sia; Po, Pang; Yuan, Youzhu; Tsang, Shik Chi Edman

    2016-01-01

    Incorporation of Zn atoms into a nanosize Cu lattice is known to alter the electronic properties of Cu, improving catalytic performance in a number of industrially important reactions. However the structural influence of Zn on the Cu phase is not well studied. Here, we show that Cu nano-clusters modified with increasing concentration of Zn, derived from ZnO support doped with Ga(3+), can dramatically enhance their stability against metal sintering. As a result, the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol, an important reaction well known for deactivation from copper nanoparticle sintering, can show greatly enhanced activity and stability with the CuZn alloy catalysts due to no noticeable sintering. HRTEM, nano-diffraction and EXAFS characterization reveal the presence of a small beta-brass CuZn alloy phase (body-centred cubic, bcc) which appears to greatly stabilise Cu atoms from aggregation in accelerated deactivation tests. DFT calculations also indicate that the small bcc CuZn phase is more stable against Cu adatom migration than the fcc CuZn phase with the ability to maintain a higher Cu dispersion on its surface. PMID:26856760

  16. Propylene glycol monomethyl ether (PGME)

    Integrated Risk Information System (IRIS)

    Propylene glycol monomethyl ether ( PGME ) ; CASRN 107 - 98 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assess

  17. GLYCOLIC - FORMIC ACID FLOWSHEET DEVELOPMENT

    SciTech Connect

    Pickenheim, B.; Stone, M.; Newell, J.

    2010-11-08

    Flowsheet testing was performed to further develop the nitric/glycolic/formic acid flowsheet as an alternative to the nitric/formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be removed in the Sludge Receipt and Adjustment Tank (SRAT) with minimal hydrogen generation. All other processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Eight runs were performed in total, including the baseline run. The baseline nitric/formic flowsheet run was extremely difficult to process under existing DWPF acceptance criteria with this simulant at the HM levels of noble metals. While nitrite was destroyed and mercury was removed to near the DWPF limit, the rheology of the SRAT and SME products were well above design basis and hydrogen generation far exceeded the DWPF limit. In addition, mixing during the SME cycle was very poor. In this sense, the nitric/glycolic/formic acid flowsheet represents a significant upgrade over the current flowsheet. In the nitric/glycolic/formic flowsheet runs, mercury was successfully removed with almost no hydrogen generation and the SRAT and SME products yield stresses were within process limits or previously processed ranges. It is recommended that DWPF continue to support development of the nitric/glycolic/formic flowsheet. Although experience is limited at this time, this flowsheet meets or outperforms the current flowsheet in many regards, including off-gas generation, mercury removal, product rheology and general ease of processing. Additional flowsheet testing will allow for a more thorough understanding of the chemistry and effectiveness of the flowsheet over a range of sludge compositions and formic/glycolic ratios. This testing will also show whether the REDOX and metal solubility concerns with this change in the flowsheet can be addressed by just adjusting the volumes of

  18. 21 CFR 184.1666 - Propylene glycol.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol. 184.1666 Section 184.1666 Food... GRAS § 184.1666 Propylene glycol. (a) Propylene glycol (C3H8O2, CAS Reg. No. 57-55-6) is known as 1,2-propanediol. It does not occur in nature. Propylene glycol is manufactured by treating propylene...

  19. 21 CFR 184.1666 - Propylene glycol.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Propylene glycol. 184.1666 Section 184.1666 Food... Specific Substances Affirmed as GRAS § 184.1666 Propylene glycol. (a) Propylene glycol (C3H8O2, CAS Reg. No. 57-55-6) is known as 1,2-propanediol. It does not occur in nature. Propylene glycol is...

  20. 21 CFR 184.1666 - Propylene glycol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Propylene glycol. 184.1666 Section 184.1666 Food... Specific Substances Affirmed as GRAS § 184.1666 Propylene glycol. (a) Propylene glycol (C3H8O2, CAS Reg. No. 57-55-6) is known as 1,2-propanediol. It does not occur in nature. Propylene glycol is...

  1. RUMINAL FERMENTATION OF PROPYLENE GLYCOL AND GLYCEROL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine rumen fluid was fermented anaerobically with 25 mM R-propylene glycol, S-propylene glycol, or glycerol added. After 24 h all of the propylene glycol enantiomers and approximately 80% of the glycerol were metabolized. Acetate, propionate, butyrate, valerate, and caproate concentrations, in dec...

  2. Glycolate transporter of the pea chloroplast envelope

    SciTech Connect

    Howitz, K.T.

    1985-01-01

    The discovery of a glycolate transporter in the pea (Pisum sativum) chloroplast envelope is described. Several novel silicone oil centrifugation methods were developed to resolve the initial rate kinetics of (/sup 14/C)glycolate transport by isolated, intact pea chloroplasts. Chloroplast glycolate transport was found to be carrier mediated. Transport rates saturated with increasing glycolate concentration. N-Ethylmaleimide (NEM) pretreatment of chloroplasts inhibited transport, an inhibition prevented by glycolate. Glycolate distributed across the envelope in a way which equalized stromal and medium glycolic acid concentrations, limiting possible transport mechanisms to facilitated glycolic acid diffusion, proton symport or hydroxyl antiport. The effects of stomal and medium pH's on the K/sub m/ and V/sub max/ fit the predictions of mobile carrier kinetic models of hydroxyl antiport or proton symport (H/sup +/ binds first). The carrier mediated transport was fast enough to be consistent with in vivo rates of photorespiration. The 2-hydroxymonocarboxylates, glycerate, lactate and glyoxylate are competitive inhibitors of chloroplast glycolate uptake. Glyoxylate, D-lactate and D-glycerate cause glycolate counterflow, indicating that they are also substrates of the glycolate carrier. This finding was confirmed for D-glycerate by studies on glycolate effects on (1-/sup 14/C)D-glycerate transport.

  3. 21 CFR 582.1666 - Propylene glycol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This...

  4. 21 CFR 582.4666 - Propylene glycol.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is...

  5. 21 CFR 582.4666 - Propylene glycol.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is...

  6. 21 CFR 582.1666 - Propylene glycol.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This...

  7. Pumping glycol solutions in the HVAC industry

    SciTech Connect

    Rishel, J.B.; Schlachter, J.P.

    1997-12-31

    Ethylene and propylene glycols are used in heating, ventilating, and airconditioning (HVAC) water systems for operations that can occur below the freezing point of pure water. Typical applications are for generating ice storage and preventing freezing in coils that are exposed to outside air. The type of glycol and the percentage of solution to be used are decisions that are made by the designer of the water system utilizing the glycols. The purpose of this paper is to (1) present the basic procedures required for the selection of piping and pumps for the glycol that has been selected for a particular water system and (2) to demonstrate the effect that the specific gravity and the viscosity of the glycol solution can have on pipe friction and pump performance. Although much of this information has been presented in other ASHRAE technical documents, it is repeated here in the hopes that a relatively simple procedure will be provided for determining the effect of glycol solution viscosity and specific gravity upon piping design and pump operation. A brief review will be made of a glycol`s characteristics followed by the procedures for calculation of piping friction for a glycol system and computation of pump performance. Review also will be made of the use of variable-speed pumping on glycol systems. All of the information will be based upon ethylene glycol; similar data and calculations could be generated for propylene glycol.

  8. 21 CFR 582.1666 - Propylene glycol.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This...

  9. 21 CFR 582.1666 - Propylene glycol.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This...

  10. 21 CFR 582.4666 - Propylene glycol.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is...

  11. 21 CFR 582.4666 - Propylene glycol.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is...

  12. 21 CFR 582.4666 - Propylene glycol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Propylene glycol. 582.4666 Section 582.4666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This substance is...

  13. 21 CFR 582.1666 - Propylene glycol.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Propylene glycol. 582.1666 Section 582.1666 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1666 Propylene glycol. (a) Product. Propylene glycol. (b) Conditions of use. This...

  14. Heme/copper terminal oxidases

    SciTech Connect

    Ferguson-Miller, S.; Babcock, G.T.

    1996-11-01

    Spatially well-organized electron-transfer reactions in a series of membrane-bound redox proteins form the basis for energy conservation in both photosynthesis and respiration. The membrane-bound nature of the electron-transfer processes is critical, as the free energy made available in exergonic redox chemistry is used to generate transmembrane proton concentration and electrostatic potential gradients. These gradients are subsequently used to drive ATP formation, which provides the immediate energy source for constructive cellular processes. The terminal heme/copper oxidases in respiratory electron-transfer chains illustrate a number of the thermodynamic and structural principles that have driven the development of respiration. This class of enzyme reduces dioxygen to water, thus clearing the respiratory system of low-energy electrons so that sustained electron transfer and free-energy transduction can occur. By using dioxygen as the oxidizing substrate, free-energy production per electron through the chain is substantial, owing to the high reduction potential of O{sub 2} (0.815 V at pH 7). 122 refs.

  15. Promoter isolation and characterization of GhAO-like1, a Gossypium hirsutum gene similar to multicopper oxidases that is highly expressed in reproductive organs.

    PubMed

    Lambret-Frotté, Julia; Artico, Sinara; Muniz Nardeli, Sarah; Fonseca, Fernando; Brilhante Oliveira-Neto, Osmundo; Grossi-de-Sá, Maria Fatima; Alves-Ferreira, Marcio

    2016-01-01

    Cotton is one of the most economically important cultivated crops. It is the major source of natural fiber for the textile industry and an important target for genetic modification for both biotic stress and herbicide tolerance. Therefore, the characterization of genes and regulatory regions that might be useful for genetic transformation is indispensable. The isolation and characterization of new regulatory regions is of great importance to drive transgene expression in genetically modified crops. One of the major drawbacks in cotton production is pest damage; therefore, the most promising, cost-effective, and sustainable method for pest control is the development of genetically resistant cotton lines. Considering this scenario, our group isolated and characterized the promoter region of a MCO (multicopper oxidase) from Gossypium hirsutum, named GhAO-like1 (ascorbate oxidase-like1). The quantitative expression, together with the in vivo characterization of the promoter region reveals that GhAO-like1 has a flower- and fruit-specific expression pattern. The GUS activity is mainly observed in stamens, as expected considering that the GhAO-like1 regulatory sequence is enriched in cis elements, which have been characterized as a target of reproductive tissue specific transcription factors. Both histological and quantitative analyses in Arabidopsis thaliana have confirmed flower (mainly in stamens) and fruit expression of GhAO-like1. In the present paper, we isolated and characterized both in silico and in vivo the promoter region of the GhAO-like1 gene. The regulatory region of GhAO-like1 might be useful to confer tissue-specific expression in genetically modified plants. PMID:26692462

  16. Nuclear-encoded cytochrome c oxidase subunit 4 regulates BMI1 expression and determines proliferative capacity of high-grade gliomas

    PubMed Central

    Oliva, Claudia R.; Markert, Tahireh; Gillespie, G. Yancey; Griguer, Corinne E.

    2015-01-01

    Nuclear-encoded cytochrome c oxidase subunit 4 (COX4) is a key regulatory subunit of mammalian cytochrome c oxidase, and recent studies have demonstrated that COX4 isoform 1 (COX4-1) could have a role in glioma chemoresistance. The Polycomb complex protein BMI1 is a stem cell regulatory gene implicated in the pathogenesis of many aggressive cancers, including glioma. This study sought to determine if COX4 regulates BMI1 and modulates tumor cell proliferation. Using The Cancer Genome Atlas database and a retrospective data set from patients with glioblastoma multiforme, we found that BMI1 expression levels positively correlated with COX4-1 expression and overall survival. Whereas COX4-1 promoted cell growth by increasing BMI1 expression, COX4-2 inhibited cell growth even in cells overexpressing BMI1. We also demonstrate that COX4-1 attenuates mitochondrial reactive oxygen species (ROS) production, which is required for COX4-1-mediated effects on BMI1 expression and cell proliferation. Notably, mice bearing COX4-1-expressing glioma cell xenografts quickly developed invasive tumors characterized by the presence of multiple lesions positive for Ki-67, BMI1, and COX4-1, whereas mice bearing COX4-2-expressing xenografts rarely developed tumors by this point. COX4-1 also promoted the self-renewal of glioma stem-like cells, consistent with the reported role of BMI1 in stem cell growth. Taken together, these findings identify a novel COX4-1-mitochondrial ROS axis, in which differential expression of COX4 isoforms regulates mitochondrial ROS production and controls BMI1 expression. PMID:25726526

  17. Coupling in cytochrome c oxidase

    PubMed Central

    Kessler, R. J.; Blondin, G. A.; Zande, H. Vande; Haworth, R. A.; Green, D. E.

    1977-01-01

    Cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase; EC 1.9.3.1) can be resolved into an electron transfer complex (ETC) and an ionophore transfer complex (ITC). Coupling requires an interaction between the moving electron in the ETC and a moving, positively charged ionophore-cation adduct in the ITC. The duplex character of cytochrome oxidase facilitates this interaction. The ITC mediates cyclical cation transport. It can be replaced as the coupling partner by the combination of valinomycin and nigericin in the presence of K+ when cytochrome oxidase is incorporated into liposomes containing acidic phospholipids or by the combination of lipid cytochrome c and bile acids in an ITC-resolved preparation of the ETC. Respiratory control can be induced by incorporating cytochrome oxidase into vesicles of unfractionated whole mitochondrial lipid. The activity of the ITC is suppressed by such incorporation and this suppression leads to the emergence of respiratory control. The ionophoroproteins of the ITC can be extracted into organic solvents; some 50% of the total protein of cytochrome oxidase is extractable. The release of free ionophore is achieved by tryptic digestion of the ionophoroprotein. Preliminary to this release the ionophoroprotein is degraded to an ionophoropeptide. Electrogenic ionophores, as well as uncoupler, are liberated by such proteolysis. The ITC contains a set of ionophoroproteins imbedded in a matrix of phospholipid. Images PMID:198794

  18. Final report on the safety assessment of PEG-25 propylene glycol stearate, PEG-75 propylene glycol stearate, PEG-120 propylene glycol stearate, PEG-10 propylene glycol, PEG-8 propylene glycol cocoate, and PEG-55 propylene glycol oleate.

    PubMed

    Johnson, W

    2001-01-01

    The ingredients considered in this safety assessment are polyethylene glycol ethers of either propylene glycol itself, propylene glycol stearate, propylene glycol oleate, or propylene glycol cocoate. They function in cosmetic formulations as surfactant--cleansing agents; surfactant-solubilizing agents; surfactant--emulsifying agents; skin conditioning agents--humectant; skin-conditioning agents--emollient; and solvents. Those in current use are used in only a small number of cosmetic formulations. Some are not currently used. Polyethylene Glycol (PEG) Propylene Glycol Cocoates and PEG Propylene Glycol Oleates are produced by the esterification of polyoxyalkyl alcohols with lauric acid and oleic acid, respectively. Although there is no information available on the method of manufacture of the other polymers, information was available describing impurities, including ethylene oxide (maximum 1 ppm), 1,4-dioxane (maximum 5 ppm), polycyclic aromatic compounds (maximum 1 ppm), and heavy metals-lead, iron, cobalt, nickel, cadmium, and arsenic included (maximum 10 ppm combined). In an acute oral toxicity study, PEG-25 Propylene Glycol Stearate was not toxic. An antiperspirant product containing 2.0% PEG-25 Propylene Glycol Stearate was nonirritating to mildly irritating to the eyes of rabbits. This product was also practically nonirritating to the skin of rabbits in single-insult occlusive patch tests. In a guinea pig sensitization test, PEG-25 Propylene Glycol Stearate was classified as nonallergenic at challenge concentrations of 25% and 50% in petrolatum. PEG-25 Propylene Glycol Stearate and PEG-55 Propylene Glycol Oleate were negative in clinical patch tests. Based on the available data, it was concluded that these ingredients are safe as used (concentrations no greater than 10%) in cosmetic formulations. Based on evidence of sensitization and nephrotoxicity in burn patients treated with a PEG-based antimicrobial preparation, the ingredients included in this review

  19. Expression of alternative oxidase in tomato

    SciTech Connect

    Kakefuda, M.; McIntosh, L. )

    1990-05-01

    Tomato fruit ripening is characterized by an increase in ethylene biosynthesis, a burst in respiration (i.e. the climacteric), fruit softening and pigmentation. As whole tomatoes ripened from mature green to red, there was an increase in the alternative oxidase capacity. Aging pink tomato slices for 24 and 48 hrs also showed an increase of alternative oxidase and cytochrome oxidase capacities. Monoclonal antibodies prepared to the Sauromatum guttatum alternative oxidase were used to follow the appearance of alternative oxidase in tomato fruits. There is a corresponding increase in a 36kDa protein with an increase in alternative oxidase capacity. Effects of ethylene and norbornadiene on alternative oxidase capacity were also studied. We are using an alternative oxidase cDNA clone from potato to study the expression of mRNA in ripening and wounded tomatoes to determine if the gene is transcriptionally regulated.

  20. Ethylene glycol poisoning in sheep.

    PubMed

    2015-05-16

    Oxalate toxicity in sheep as a consequence of exposure to ethylene glycol. Chlamydophila abortus infection in a dairy cow. Neosporosis diagnosed in a newborn lamb with deformities. Yersiniosis affecting a 1000-strong goat herd. Porcine reproductive and respiratory syndrome causing blue ears in 14-week-old pigs. Avian tuberculosis diagnosed in an adult Mandarin duck. These are among matters discussed in the Animal and Plant Health Agency's (APHA's) disease surveillance report for January and February 2015. PMID:25977491

  1. Polyethylene glycol plus ascorbic acid for bowel preparation in chronic kidney disease.

    PubMed

    Lee, Jae Min; Keum, Bora; Yoo, In Kyung; Kim, Seung Han; Choi, Hyuk Soon; Kim, Eun Sun; Seo, Yeon Seok; Jeen, Yoon Tae; Chun, Hoon Jai; Lee, Hong Sik; Um, Soon Ho; Kim, Chang Duck; Kim, Myung Gyu; Jo, Sang Kyung

    2016-09-01

    The safety of polyethylene glycol plus ascorbic acid has not been fully investigated in patients with renal insufficiency. High-dose ascorbic acid could induce hyperoxaluria, thereby causing tubule-interstitial nephritis and renal failure. This study aims to evaluate the safety and efficacy of polyethylene glycol plus ascorbic acid in patients with chronic kidney disease.We retrospectively reviewed prospectively collected data on colonoscopy in patients with impaired renal function. Patients were divided into 2 groups: 2 L polyethylene glycol plus ascorbic acid (n = 61) and 4 L polyethylene glycol (n = 80). The safety of the 2 groups was compared by assessing the differences in laboratory findings before and after bowel cleansing.The laboratory findings were not significantly different before and after the administration of 2 L polyethylene glycol plus ascorbic acid or 4 L polyethylene glycol. In both groups, the estimated glomerular filtration rate was not influenced by the administration of the bowel-cleansing agent. Patients' reports on tolerance and acceptability were better in the 2 L polyethylene glycol plus ascorbic acid group than in the 4 L polyethylene glycol group.The 2 L polyethylene glycol plus ascorbic acid solution is a safe choice for bowel preparation before colonoscopy in patients with impaired renal function. PMID:27603372

  2. Measuring exposures to glycol ethers.

    PubMed

    Clapp, D E; Zaebst, D D; Herrick, R F

    1984-08-01

    In 1981, NIOSH began investigating the potential reproductive health effects resulting from exposures to a class of organic solvents known generically as glycol ethers (GE). This research was begun as a result of the NIOSH criteria document development program which revealed little data available on the health effects of glycol ether exposure. Toxicologic research was begun by NIOSH and other researchers which suggested substantial reproductive effects in animals. These animal data motivated a study of human exposures in the occupational setting. In 1981 and 1982 NIOSH conducted several walk-through surveys which included preliminary measurements of exposures in a variety of industries including painting trades, coal mining, production blending and distribution facilities, aircraft fueling, and communications equipment repair facilities. The human exposure data from these surveys is summarized in this paper with most results well below 1 parts per million (ppm) and only a few values approaching 10 ppm. Blood samples were collected at one site resulting in GE concentrations below the limit of detection. Exposures to airborne glycol ethers, in the industries investigated during the collection of this data, revealed several problems in reliably sampling GE at low concentrations. It became apparent, from the data and observations of work practices, that air monitoring alone provided an inadequate index of GE exposure. Further field studies of exposure to GE are anticipated, pending location of additional groups of exposed workers and development of more reliable methods for characterizing exposure, especially biological monitoring. PMID:6499824

  3. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth

    PubMed Central

    Forte, Elena; Borisov, Vitaliy B.; Falabella, Micol; Colaço, Henrique G.; Tinajero-Trejo, Mariana; Poole, Robert K.; Vicente, João B.; Sarti, Paolo; Giuffrè, Alessandro

    2016-01-01

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed. PMID:27030302

  4. MCF-7 cells expressing nuclear associated lysyl oxidase-like 2 (LOXL2) exhibit an epithelial-to-mesenchymal transition (EMT) phenotype and are highly invasive in vitro.

    PubMed

    Moon, Hee-Jung; Finney, Joel; Xu, Li; Moore, David; Welch, Danny R; Mure, Minae

    2013-10-18

    LOXL2 is a copper- and lysine tyrosylquinone-dependent amine oxidase that has been proposed to function both extracellularly and intracellularly to activate oncogenic signaling pathways leading to EMT and invasion of breast cancer cells. In this study, we selected MCF-7 cells that stably express forms of recombinant LOXL2 differing in their subcellular localizations and catalytic competencies. This enabled us to dissect the molecular functions of intracellular and extracellular LOXL2s and examine their contributions to breast cancer metastasis/invasion. We discovered that secreted LOXL2 (~100-kDa) is N-glycosylated at Asn-455 and Asn-644, whereas intracellular LOXL2 (~75-kDa) is nonglycosylated and N-terminally processed, and is primarily associated with the nucleus. Both forms of LOXL2 can oxidize lysine in solution. However, we found that expression of intracellular LOXL2 is more strongly associated with EMT and invasiveness than secreted LOXL2 in vitro. The results indicate that nuclear associated LOXL2 contributes to the stabilization of Snail1 transcription factor at the protein level to induce EMT and promote invasion in vitro, through repression of E-cadherin, occludin, and estrogen receptor-α, and up-regulation of vimentin, fibronectin, and MT1-MMP. PMID:24014025

  5. Lysyl Oxidase Gene G473A Polymorphism and Cigarette Smoking in Association with a High Risk of Lung and Colorectal Cancers in a North Chinese Population

    PubMed Central

    Wang, Guoli; Shen, Yanqing; Cheng, Guang; Bo, Haimei; Lin, Jia; Zheng, Maogen; Li, Jianmin; Zhao, Yinzhi; Li, Wande

    2016-01-01

    The relationship among the lysyl oxidase (LOX) G473A single nucleotide polymorphism (SNP), cigarette smoking and lung, colorectal, colon and rectum cancer susceptibility was studied in 200 cases of lung cancer, 335 cases of colorectal cancer including 130 cases of colon cancer and 205 cases of rectum cancer, and 335 healthy people in Tangshan, China. Peripheral blood DNA samples were collected, DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) performed, followed by multivariate logistic regression analysis. In comparison to LOX473GG genotype carriers, individuals with LOX473AA exhibited a higher susceptibility to lung, colon-rectum, colon, and rectum cancers with OR values amounting to 3.84-, 2.74-, 2.75-, and 2.74-fold of the control, respectively. In the LOX 473AA-positive population, females were more susceptible than males to carcinogenesis with OR values (female vs. male): 5.25 vs. 3.23, 2.29 vs. 1.51, 2.27 vs. 1.45, and 2.25 vs. 1.53, respectively, for lung, colon-rectum combined, colon, and rectum cancers. LOX G473A polymorphism apparently elevated human sensitivity to cigarette smoking carcinogens for eliciting cancers in the lung and colon only. Thus, LOX G473A polymorphism positively correlates with carcinogenesis and it may be used as an ideal intrinsic biomarker for prediction or diagnosis of carcinogenesis in humans. PMID:27367711

  6. Assessing gibberellins oxidase activity by anion exchange/hydrophobic polymer monolithic capillary liquid chromatography-mass spectrometry.

    PubMed

    Chen, Ming-Luan; Su, Xin; Xiong, Wei; Liu, Jiu-Feng; Wu, Yan; Feng, Yu-Qi; Yuan, Bi-Feng

    2013-01-01

    Bioactive gibberellins (GAs) play a key regulatory role in plant growth and development. In the biosynthesis of GAs, GA3-oxidase catalyzes the final step to produce bioactive GAs. Thus, the evaluation of GA3-oxidase activity is critical for elucidating the regulation mechanism of plant growth controlled by GAs. However, assessing catalytic activity of endogenous GA3-oxidase remains challenging. In the current study, we developed a capillary liquid chromatography--mass spectrometry (cLC-MS) method for the sensitive assay of in-vitro recombinant or endogenous GA3-oxidase by analyzing the catalytic substrates and products of GA3-oxidase (GA1, GA4, GA9, GA20). An anion exchange/hydrophobic poly([2-(methacryloyloxy)ethyl]trimethylammonium-co-divinylbenzene-co-ethylene glycol dimethacrylate)(META-co-DVB-co-EDMA) monolithic column was successfully prepared for the separation of all target GAs. The limits of detection (LODs, Signal/Noise = 3) of GAs were in the range of 0.62-0.90 fmol. We determined the kinetic parameters (K m) of recombinant GA3-oxidase in Escherichia coli (E. coli) cell lysates, which is consistent with previous reports. Furthermore, by using isotope labeled substrates, we successfully evaluated the activity of endogenous GA3-oxidase that converts GA9 to GA4 in four types of plant samples, which is, to the best of our knowledge, the first report for the quantification of the activity of endogenous GA3-oxidase in plant. Taken together, the method developed here provides a good solution for the evaluation of endogenous GA3-oxidase activity in plant, which may promote the in-depth study of the growth regulation mechanism governed by GAs in plant physiology. PMID:23922762

  7. Assessing Gibberellins Oxidase Activity by Anion Exchange/Hydrophobic Polymer Monolithic Capillary Liquid Chromatography-Mass Spectrometry

    PubMed Central

    Liu, Jiu-Feng; Wu, Yan; Feng, Yu-Qi; Yuan, Bi-Feng

    2013-01-01

    Bioactive gibberellins (GAs) play a key regulatory role in plant growth and development. In the biosynthesis of GAs, GA3-oxidase catalyzes the final step to produce bioactive GAs. Thus, the evaluation of GA3-oxidase activity is critical for elucidating the regulation mechanism of plant growth controlled by GAs. However, assessing catalytic activity of endogenous GA3-oxidase remains challenging. In the current study, we developed a capillary liquid chromatography – mass spectrometry (cLC-MS) method for the sensitive assay of in-vitro recombinant or endogenous GA3-oxidase by analyzing the catalytic substrates and products of GA3-oxidase (GA1, GA4, GA9, GA20). An anion exchange/hydrophobic poly([2-(methacryloyloxy)ethyl]trimethylammonium-co-divinylbenzene-co-ethylene glycol dimethacrylate)(META-co-DVB-co-EDMA) monolithic column was successfully prepared for the separation of all target GAs. The limits of detection (LODs, Signal/Noise = 3) of GAs were in the range of 0.62–0.90 fmol. We determined the kinetic parameters (Km) of recombinant GA3-oxidase in Escherichia coli (E. coli) cell lysates, which is consistent with previous reports. Furthermore, by using isotope labeled substrates, we successfully evaluated the activity of endogenous GA3-oxidase that converts GA9 to GA4 in four types of plant samples, which is, to the best of our knowledge, the first report for the quantification of the activity of endogenous GA3-oxidase in plant. Taken together, the method developed here provides a good solution for the evaluation of endogenous GA3-oxidase activity in plant, which may promote the in-depth study of the growth regulation mechanism governed by GAs in plant physiology. PMID:23922762

  8. Protoporphyrinogen Oxidase-Inhibiting Herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protoporphyrinogen oxidase-inhibiting herbicides (also referred to as Protox- or PPO-inhibiting herbicides) were commercialized in the 1960s and their market share reached approximately 10% (total herbicide active ingredient output) in the late 1990’s. The wide-spread adoption of glyphosate-resista...

  9. Characterization of wheat germin (oxalate oxidase) expressed by Pichia pastoris

    SciTech Connect

    Pan, Heng-Yen; Whittaker, Mei M.; Bouveret, Romaric; Berna, Anne; Bernier, Francois; Whittaker, James W. . E-mail: jim@ebs.ogi.edu

    2007-05-18

    High-level secretory expression of wheat (Triticum aestivum) germin/oxalate oxidase was achieved in Pichia pastoris fermentation cultures as an {alpha}-mating factor signal peptide fusion, based on the native wheat cDNA coding sequence. The oxalate oxidase activity of the recombinant enzyme is substantially increased (7-fold) by treatment with sodium periodate, followed by ascorbate reduction. Using these methods, approximately 1 g (4 x 10{sup 4} U) of purified, activated enzyme was obtained following eight days of induction of a high density Pichia fermentation culture, demonstrating suitability for large-scale production of oxalate oxidase for biotechnological applications. Characterization of the recombinant protein shows that it is glycosylated, with N-linked glycan attached at Asn47. For potential biomedical applications, a nonglycosylated (S49A) variant was also prepared which retains essentially full enzyme activity, but exhibits altered protein-protein interactions.

  10. Why use glycols in HVAC systems?

    SciTech Connect

    Eppelheimer, D.M.

    1997-12-31

    Glycols are used to prevent damage to heating, ventilating, and airconditioning (HVAC) equipment due to freezing and corrosion. Two glycols enjoy wide acceptance--ethylene glycol and propylene glycol. Both glycols have lower heat transfer characteristics and increased pumping requirements when compared to water. The loss of heat transfer and the increase in pumping power are influenced by temperature and the concentration of the fluid. The physical effects of glycol are almost unnoticed in heating systems where higher temperatures prevail. However, in cooling applications, the effect of glycol on system capacity and pump power must be carefully considered. Capricious addition of glycol to cooling systems is inappropriate. The effects of glycol can be mitigated by careful selection of equipment. This paper illustrates methods by which to reduce the impact of glycols when selecting cooling coils and chillers. Techniques such as increasing log mean temperature difference (LMTD) and modifications in coil circuiting or tube geometry can have a dramatic effect. The benefits of these techniques will be reviewed.

  11. Different metabolic fate of two carbons of glycolate in its conversion to serine in Euglena gracilis z

    SciTech Connect

    Yokota, A.; Komura, H.; Kitaoka, S.

    1985-11-01

    In previons work, extensive decarboxylation of glycolate carboxyl carbon during its metabolism in Euglena gracilis suggested occurrence of a metabolic pathway of glycolate different from that of higher C/sub 3/ plants. In the present report, the authors establish the Euglena glycolate pathway from characteristics of the decarboxylation of the carboxyl carbon and from the metabolic fate of hydroxymethyl carbon of glycolate. The ratio of the decarboxylation of the carboxyl carbon of glycolate to the total metabolized carbon increased with increasing metabolic rate in an asymptotic fashion. Metabolic products were also changed depending on the rate of metabolism of glycolate; glycine was the main product at the low rate of glycolate metabolism and the contribution of glycine was reversed by the increased contribution of evolved CO/sub 2/ at the high rates. Experiments with (2-/sup 14/C)glycolate showed that exogenously added formate and methionine caused accumulation of radioactive formate. Based on these results, they have proposed that the glycolate metabolism of E. gracilis consists of glycine and formate pathways and that the relative contribution of both pathways to the glycolate metabolism depends on the metabolic rate of glycolate.

  12. Chromate reduction by rabbit liver aldehyde oxidase

    SciTech Connect

    Banks, R.B.; Cooke, R.T. Jr.

    1986-05-29

    Chromate was reduced during the oxidation of 1-methylnicotinamide chlorine by partially purified rabbit liver aldehyde oxidase. In addition to l-methylnicotinamide, several other electron donor substrates for aldehyde oxidase were able to support the enzymatic chromate reduction. The reduction required the presence of both enzyme and the electron donor substrate. The rate of the chromate reduction was retarded by inhibitors or aldehyde oxidase but was not affected by substrates or inhibitors of xanthine oxidase. These results are consistent with the involvement of aldehyde oxidase in the reduction of chromate by rabbit liver cytosolic enzyme preparations.

  13. [Amperometric enzyme biosensor with a glucose oxidase-polyaniline membrane].

    PubMed

    Dziadevich, S V; Doldatkin, A P; Rossokhatyĭ, V K; Shram, N F; Shul'ga, A A; Strikha, V I

    1994-01-01

    An amperometric glucose biosensor was made by electrochemical polymerization of aniline onto the gold electrodes in presence of the enzyme glucose oxidase in the phosphate buffer solution with pH 7.0. Aniline is easily polymerized forming a thin film, which adheres tightly on the electrodes surface. During the electropolymerization process glucose oxidase was entrapped into polyaniline film which then became the catalyst of the enzyme reaction of glucose hydrolysis. Experiments were performed to determine optimal conditions of polyaniline-glucose oxidase film preparation. Glucose was amperometrically determined with the electrochemically fabricated biosensor in the concentration range 10(-4) M to 2 x 10(-2) M. The linearity of the enzyme electrode response ranged from 2 x 10(-4) M to 6 x 10(-3) M. The electrochemical synthesis of a polyaniline-enzyme thin film a high-technologic one and this permits fabricating various microbiosensors and multisensors in the continuous technological cycle. PMID:7754558

  14. POLYAMINE OXIDASE 1 from rice (Oryza sativa) is a functional ortholog of Arabidopsis POLYAMINE OXIDASE 5

    PubMed Central

    Liu, Taibo; Wook Kim, Dong; Niitsu, Masaru; Berberich, Thomas; Kusano, Tomonobu

    2014-01-01

    POLYAMINE OXIDASE 1 (OsPAO1), from rice (Oryza sativa), and POLYAMINE OXIDASE 5 (AtPAO5), from Arabidopsis (Arabidopsis thaliana), are enzymes sharing high identity at the amino acid level and with similar characteristics, such as polyamine specificity and pH preference; furthermore, both proteins localize to the cytosol. A loss-of-function Arabidopsis mutant, Atpao5–2, was hypersensitive to low doses of exogenous thermospermine but this phenotype could be rescued by introduction of the wild-type AtPAO5 gene. Introduction of OsPAO1, under the control of a constitutive promoter, into Atpao5–2 mutants also restored normal thermospermine sensitivity, allowing growth in the presence of low levels of thermospermine, along with a concomitant decrease in thermospermine content in plants. By contrast, introduction of OsPAO3, which encodes a peroxisome-localized polyamine oxidase, into Atpao5–2 plants could not rescue any of the mutant phenotypes in the presence of thermospermine. These results suggest that OsPAO1 is the functional ortholog of AtPAO5. PMID:25763711

  15. POLYAMINE OXIDASE 1 from rice (Oryza sativa) is a functional ortholog of Arabidopsis POLYAMINE OXIDASE 5.

    PubMed

    Liu, Taibo; Wook Kim, Dong; Niitsu, Masaru; Berberich, Thomas; Kusano, Tomonobu

    2014-07-25

    POLYAMINE OXIDASE 1 (OsPAO1), from rice (Oryza sativa), and POLYAMINE OXIDASE 5 (AtPAO5), from Arabidopsis (Arabidopsis thaliana), are enzymes sharing high identity at the amino acid level and with similar characteristics, such as polyamine specificity and pH preference; furthermore, both proteins localize to the cytosol. A loss-of-function Arabidopsis mutant, Atpao5-2, was hypersensitive to low doses of exogenous thermospermine but this phenotype could be rescued by introduction of the wild-type AtPAO5 gene. Introduction of OsPAO1, under the control of a constitutive promoter, into Atpao5-2 mutants also restored normal thermospermine sensitivity, allowing growth in the presence of low levels of thermospermine, along with a concomitant decrease in thermospermine content in plants. By contrast, introduction of OsPAO3, which encodes a peroxisome-localized polyamine oxidase, into Atpao5-2 plants could not rescue any of the mutant phenotypes in the presence of thermospermine. These results suggest that OsPAO1 is the functional ortholog of AtPAO5. PMID:25061821

  16. Ethylene glycol, hazardous substance in the household.

    PubMed

    Patocka, Jirí; Hon, Zdenek

    2010-01-01

    Ethylene glycol is a colorless, odorless, sweet-tasting but poisonous type of alcohol found in many household products. The major use of ethylene glycol is as an antifreeze in, for example, automobiles, in air conditioning systems, in de-icing fluid for windshields, and else. People sometimes drink ethylene glycol mistakenly or on purpose as a substitute for alcohol. Ethylene glycol is toxic, and its drinking should be considered a medical emergency. The major danger from ethylene glycol is following ingestion. Due to its sweet taste, peoples and occasionally animals will sometimes consume large quantities of it if given access to antifreeze. While ethylene glycol itself has a relatively low degree of toxicity, its metabolites are responsible for extensive cellular damage to various tissues, especially the kidneys. This injury is caused by the metabolites, glycolic and oxalic acid and their respective salts, through crystal formation and possibly other mechanisms. Toxic metabolites of ethylene glycol can damage the brain, liver, kidneys, and lungs. The poisoning causes disturbances in the metabolism pathways, including metabolic acidosis. The disturbances may be severe enough to cause profound shock, organ failure, and death. Ethylene glycol is a common poisoning requiring antidotal treatment. PMID:20608228

  17. Cooling in the tropics: ethylene glycol overdose.

    PubMed

    Holyoak, Adam L; Fraser, Todd A; Gelperowicz, Pascal

    2011-03-01

    Ethylene glycol is the active ingredient used in radiator antifreeze. Severe ingestions of ethylene glycol are uncommon in Australia, but if untreated, can result in multiorgan dysfunction, particularly renal failure and cerebral oedema. We report on a patient who consumed a large quantity of ethylene glycol. He was treated with enteral ethanol and went on to make a full recovery, despite an initial moribund state. We briefly review the pathophysiology and current treatment strategies for ethylene glycol intoxication, and discuss issues surrounding enteral versus parenteral ethanol administration. PMID:21355826

  18. The fabrication of monolithic capillary column based on poly (bisphenol A epoxy vinyl ester resin-co-ethylene glycol dimethacrylate) and its applications for the separation of small molecules in high performance liquid chromatography.

    PubMed

    Niu, Wenjing; Wang, Lijuan; Bai, Ligai; Yang, Gengliang

    2013-07-01

    A new polymeric monolith was synthesized in fused-silica capillary by in situ polymerization technique. In the polymerization, bisphenol A epoxy vinyl ester resin (VER) was used as the functional monomer, ethylene glycol dimethacrylate (EDMA) as the crosslinking monomer, 1,4-butanediol, 1-propanol and water as the co-porogens, and azobisisobutyronitrile (AIBN) as the initiator. The conditions of polymerization have been optimized. Morphology of the prepared poly (VER-co-EDMA) monolith was investigated by the scanning electron microscopy (SEM); pore properties were assayed by mercury porosimetry and nitrogen adsorption. The optimized poly (VER-co-EDMA) monolith showed a uniform structure, good permeability and mechanical stability. Then, the column was used as the stationary phase of high performance liquid chromatography (HPLC) to separate the mixture of benzene derivatives. The best column efficiency achieved for phenol was 235790 theoretical plates per meter. Baseline separations of benzene derivatives and halogenated benzene compounds under optimized isocratic mode conditions were achieved with high column efficiency. The column showed good reproducibility: the relative standard deviation (RSD) values based on the retention times (n=3) for run-to-run, column-to-column and batch-to-batch were less than 0.98, 1.68, 5.48%, respectively. Compared with poly (BMA-co-EDMA) monolithic column, the proposed monolith exhibited more efficiency in the separation of small molecules. PMID:23726080

  19. Enhanced piezoelectricity and high temperature poling effect in (1-x)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3} ceramics via an ethylene glycol route

    SciTech Connect

    Tailor, H. N.; Ye, Z.-G.

    2010-05-15

    A solution chemical method utilizing ethylene glycol as solvent has been developed to prepare the ceramics of (1-x)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3}[(1-x)PMN-xPT] from a precursor powder that can be pressed and fired in one step to produce high quality ceramics with excellent piezoelectric properties. The ceramics reach a relative density of up to 97% of the theoretical value after direct calcinations. This high density is achieved without the need of additional sintering after calcination which is usually required in conventional solid state syntheses to produce ceramics. The ceramics exhibit a unipolar piezoelectric coefficient d{sub 33} of 848 pC/N, which is one of the highest values for any unmodified/untextured binary systems reported to date. Since the piezoelectric properties depend on composition and electric field, the effect of poling conditions was investigated. A critical temperature limit has been found, above which poling can dramatically impair the piezoelectric properties due to a field-induced increase in the monoclinic phase component around the morphotropic phase boundary.

  20. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol alginate. 172.858 Section 172.858... Propylene glycol alginate. The food additive propylene glycol alginate (CAS Reg. No. 9005-37-2) may be used... the act: (1) The name of the additive, “propylene glycol alginate” or “propylene glycol ester...

  1. Effect of Cheonggukjang supplementation upon hepatic acyl-CoA synthase, carnitine palmitoyltransferase I, acyl-CoA oxidase and uncoupling protein 2 mRNA levels in C57BL/6J mice fed with high fat diet

    PubMed Central

    Soh, Ju-Ryoun; Shin, Dong-Hwa; Kwon, Dae Young

    2007-01-01

    This study investigated the effect of Cheonggukjang on mRNA levels of hepatic acyl-CoA synthase (ACS), carnitine palmitoyltransferase I (CPT-I), acyl-CoA oxidase (ACO) and uncoupling protein 2 (UCP2), and on serum lipid profiles in C57BL/6J mice. Thirty male C57BL/6J mice were divided into three groups; normal diet (ND), high fat diet (HD) and high fat diet with 40% Cheonggukjang (HDC). Energy intake was significantly higher in the HDC group than in the ND and HD groups. The HDC group normalized in weight gain, epididymal and back fat (g/100 g) accumulation which are increased by high fat diet. Serum concentrations of triglyceride and total cholesterol in the HDC were significantly lower than those in the HD group. These results were confirmed by hepatic mRNA expression of enzymes and protein (ACS, CPT-1, ACO, UCP2) which is related with lipid metabolism by RT-PCR. Hepatic CPT-I, ACO and UCP2 mRNA expression was increased by Cheonggukjang supplementation. We demonstrated that Cheonggukjang supplement leads to increased mRNA expressions of enzymes and protein involved in fatty acid oxidation in liver, reduced accumulation of body fat and improvement of serum lipids in high fat diet fed mice. PMID:18850232

  2. Urate oxidase: primary structure and evolutionary implications.

    PubMed Central

    Wu, X W; Lee, C C; Muzny, D M; Caskey, C T

    1989-01-01

    Urate oxidase, or uricase (EC 1.7.3.3), is a peroxisomal enzyme that catalyzes the oxidation of uric acid to allantoin in most mammals. In humans and certain other primates, however, the enzyme has been lost by some unknown mechanism. To identify the molecular basis for this loss, urate oxidase cDNA clones were isolated from pig, mouse, and baboon, and their DNA sequences were determined. The mouse urate oxidase open reading frame encodes a 303-amino acid polypeptide, while the pig and baboon urate oxidase cDNAs encode a 304-amino acid polypeptide due to a single codon deletion/insertion event. The authenticity of this single additional codon was confirmed by sequencing the mouse and pig genomic copies of the gene. The urate oxidase sequence contains a domain similar to the type 2 copper binding motif found in other copper binding proteins, suggesting that the copper ion in urate oxidase is coordinated as a type 2 structure. Based upon a comparison of the NH2-terminal peptide and deduced sequences, we propose that the maturation of pig urate oxidase involves the posttranslational cleavage of a six-amino acid peptide. Two nonsense mutations were found in the human urate oxidase gene, which confirms, at the molecular level, that the urate oxidase gene in humans is nonfunctional. The sequence comparisons favor the hypothesis that the loss of urate oxidase in humans is due to a sudden mutational event rather than a progressive mutational process. Images PMID:2594778

  3. Polyphenol oxidase activity in co-ensiled temperate grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO) and its o-diphenol substrates have been shown to effectively decrease proteolytic activity during the ensiling of forages such as red clover. Orchardgrass and smooth bromegrass both contain high levels of PPO activity, but lack appropriate levels of o-diphenols to adequately...

  4. Water potential of aqueous polyethylene glycol.

    PubMed

    Steuter, A A

    1981-01-01

    Water potential (Psiomega) values were determined for aqueous colloids of four molecular sizes of polyethylene glycol (PEG) using freezing-point depression and vapor-pressure deficit methods. A significant third-order interaction exists between the method used to determine Psiomega, PEG molecular size, and concentration. At low PEG concentrations, freezing-point depression measurements result in higher (less negative) values for Psiomega than do vapor-pressure deficit measurements. The reverse is true at high concentrations. PEG in water does not behave according to van't Hoff's law. Psiomega is related to molality for a given PEG but not linearly. Moreover, Psiomega varies with the molecular size of the PEG. It is suggested that the Psiomega of PEG in water may be controlled primarily by the matric forces of ethylene oxide subunits of the PEG polymer. The term matricum is proposed for PEG in soil-plant-water relation studies. PMID:16661635

  5. Monoamine oxidase B levels are highly expressed in human gliomas and are correlated with the expression of HiF-1α and with transcription factors Sp1 and Sp3

    PubMed Central

    Sharpe, Martyn A.; Baskin, David S.

    2016-01-01

    Monoamine oxidases A and B (MAOA and MAOB) are highly expressed in many cancers. Here we investigated the level of MAOB in gliomas and confirmed its high expression. We found that MAOB levels correlated with tumor grade and hypoxia-inducible factor 1-alpha (HiF-1α) expression. HiF-1α was localized to the nuclei in high-grade gliomas, but it was primarily cytosolic in low-grade gliomas and normal human astrocytes. Expression of both glial fibrillary acidic protein (GFAP) and MAOB are correlated to HiF-1α expression levels. Levels of MAOB are correlated by the levels of transcription factor Sp3 in the majority of GBM examined, but this control of MAOB expression by Sp3 in low grade astrocytic gliomas is significantly different from control in the in the majority of glioblastomas. The current findings support previous suggestions that MAOB can be exploited for the killing of cancer cells. Selective cell toxicity can be achieved by designing non-toxic prodrugs that require MAOB for their catalytic conversion into mature cytotoxic chemotherapeutics. PMID:26689994

  6. High atmospheric carbon dioxide-dependent alleviation of salt stress is linked to RESPIRATORY BURST OXIDASE 1 (RBOH1)-dependent H2O2 production in tomato (Solanum lycopersicum)

    PubMed Central

    Yi, Changyu; Yao, Kaiqian; Cai, Shuyu; Li, Huizi; Zhou, Jie; Xia, Xiaojian; Shi, Kai; Yu, Jingquan; Foyer, Christine Helen; Zhou, Yanhong

    2015-01-01

    Plants acclimate rapidly to stressful environmental conditions. Increasing atmospheric CO2 levels are predicted to influence tolerance to stresses such as soil salinity but the mechanisms are poorly understood. To resolve this issue, tomato (Solanum lycopersicum) plants were grown under ambient (380 μmol mol–1) or high (760 μmol mol–1) CO2 in the absence or presence of sodium chloride (100mM). The higher atmospheric CO2 level induced the expression of RESPIRATORY BURST OXIDASE 1 (SlRBOH1) and enhanced H2O2 accumulation in the vascular cells of roots, stems, leaf petioles, and the leaf apoplast. Plants grown with higher CO2 levels showed improved salt tolerance, together with decreased leaf transpiration rates and lower sodium concentrations in the xylem sap, vascular tissues, and leaves. Silencing SlRBOH1 abolished high CO2 -induced salt tolerance and increased leaf transpiration rates, as well as enhancing Na+ accumulation in the plants. The higher atmospheric CO2 level increased the abundance of a subset of transcripts involved in Na+ homeostasis in the controls but not in the SlRBOH1-silenced plants. It is concluded that high atmospheric CO2 concentrations increase salt stress tolerance in an apoplastic H2O2 dependent manner, by suppressing transpiration and hence Na+ delivery from the roots to the shoots, leading to decreased leaf Na+ accumulation. PMID:26417022

  7. CotA, a Multicopper Oxidase from Bacillus pumilus WH4, Exhibits Manganese-Oxidase Activity

    PubMed Central

    Su, Jianmei; Bao, Peng; Bai, Tenglong; Deng, Lin; Wu, Hui; Liu, Fan; He, Jin

    2013-01-01

    Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85±1.17 mM, 3.01×10−6±0.21 M·min−1 and 0.32±0.02 s−1, respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a

  8. NADPH oxidase of human dendritic cells: role in Candida albicans killing and regulation by interferons, dectin-1 and CD206.

    PubMed

    Donini, Marta; Zenaro, Elena; Tamassia, Nicola; Dusi, Stefano

    2007-05-01

    Human monocyte-derived DC express the enzyme NADPH oxidase, responsible for ROS production. We show that Candida albicans did not activate NADPH oxidase in DC, and was poorly killed by these cells. However, Candida-killing activity increased upon DC stimulation with the NADPH oxidase activator PMA and was further enhanced by DC treatment with IFN-alpha or IFN-gamma. This fungicidal activity took place at high DC-to-Candida ratio, but decreased at low DC-to-yeast ratio, when Candida inhibited the NADPH oxidase by contrasting the assembly of the enzyme on DC plasma membrane. The NADPH oxidase inhibitor diphenyliodonium chloride abrogated the PMA-dependent DC candidacidal capacity. Engagement of beta-glucan receptor dectin-1 induced NADPH oxidase activation in DC that was depressed by mannose-binding receptor CD206 co-stimulation. Candida was internalized by DC through mannose-binding receptors, but not through dectin-1, thus explaining why Candida did not elicit NADPH oxidase activity. Our results indicate that NADPH oxidase is involved in DC Candida-killing activity, which is increased by IFN. However, Candida escapes the oxidative damage by inhibiting NADPH oxidase and by entering DC through receptors not involved in NADPH oxidase activation. PMID:17407098

  9. Incorporation of copper into lysyl oxidase.

    PubMed

    Kosonen, T; Uriu-Hare, J Y; Clegg, M S; Keen, C L; Rucker, R B

    1997-10-01

    Lysyl oxidase is a copper-dependent enzyme involved in extracellular processing of collagens and elastin. Although it is known that copper is essential for the functional activity of the enzyme, there is little information on the incorporation of copper. In the present study we examined the insertion of copper into lysyl oxidase using 67Cu in cell-free transcription/translation assays and in normal skin fibroblast culture systems. When a full-length lysyl oxidase cDNA was used as a template for transcription/translation reactions in vitro, unprocessed prolysyl oxidase appeared to bind copper. To examine further the post-translational incorporation of copper into lysyl oxidase, confluent skin fibroblasts were incubated with inhibitors of protein synthesis (cycloheximide, 10 microg/ml), glycosylation (tunicamycin, 10 microg/ml), protein secretion (brefeldin A, 10 microg/ml) and prolysyl oxidase processing (procollagen C-peptidase inhibitor, 2.5 microg/ml) together with 300 microCi of carrier-free 67Cu. It was observed that protein synthesis was a prerequisite for copper incorporation, but inhibition of glycosylation by tunicamycin did not affect the secretion of 67Cu as lysyl oxidase. Brefeldin A inhibited the secretion of 67Ci-labelled lysyl oxidase by 46%, but the intracellular incorporation of copper into lysyl oxidase was not affected. In addition, the inhibition of the extracellular proteolytic processing of prolysyl oxidase to lysyl oxidase had minimal effects on the secretion of protein-bound 67Cu. Our results indicate that, similar to caeruloplasmin processing [Sato and Gitlin (1991) J. Biol. Chem. 266, 5128-5134], copper is inserted into prolysyl oxidase independently of glycosylation. PMID:9355764

  10. Arsenite Oxidase Also Functions as an Antimonite Oxidase

    PubMed Central

    Wang, Qian; Warelow, Thomas P.; Kang, Yoon-Suk; Romano, Christine; Osborne, Thomas H.; Lehr, Corinne R.; Bothner, Brian; McDermott, Timothy R.

    2015-01-01

    Arsenic and antimony are toxic metalloids and are considered priority environmental pollutants by the U.S. Environmental Protection Agency. Significant advances have been made in understanding microbe-arsenic interactions and how they influence arsenic redox speciation in the environment. However, even the most basic features of how and why a microorganism detects and reacts to antimony remain poorly understood. Previous work with Agrobacterium tumefaciens strain 5A concluded that oxidation of antimonite [Sb(III)] and arsenite [As(III)] required different biochemical pathways. Here, we show with in vivo experiments that a mutation in aioA [encoding the large subunit of As(III) oxidase] reduces the ability to oxidize Sb(III) by approximately one-third relative to the ability of the wild type. Further, in vitro studies with the purified As(III) oxidase from Rhizobium sp. strain NT-26 (AioA shares 94% amino acid sequence identity with AioA of A. tumefaciens) provide direct evidence of Sb(III) oxidation but also show a significantly decreased Vmax compared to that of As(III) oxidation. The aioBA genes encoding As(III) oxidase are induced by As(III) but not by Sb(III), whereas arsR gene expression is induced by both As(III) and Sb(III), suggesting that detection and transcriptional responses for As(III) and Sb(III) differ. While Sb(III) and As(III) are similar with respect to cellular extrusion (ArsB or Acr3) and interaction with ArsR, they differ in the regulatory mechanisms that control the expression of genes encoding the different Ars or Aio activities. In summary, this study documents an enzymatic basis for microbial Sb(III) oxidation, although additional Sb(III) oxidation activity also is apparent in this bacterium. PMID:25576601