The use of hypercrosslinked polymer sorbents and composites based on them in the sorption of toxic and bad-smelling substances
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Polystyrene
Plasticizer
With the discovery of hydrogen sulfide as a signaling molecule and a potential therapeutic, measurement of free sulfide in blood – as hydrogen sulfide or hydrosulfide anion – has taken on importance. Here, we demonstrate and validate a method of free sulfide measurement whereby the free sulfide in whole blood is derivatized with excess monobromobimane. The resulting sulfide‐dibimane is subsequently extracted into ethyl acetate, followed by quantitation of sulfide‐dibimane via reverse‐phase HPLC with fluorescence detection. Reaction conditions are validated through 1) characterization of rate of conversion from sulfide to sulfide‐dibimane, 2) analysis of reaction in the presence of potential interferants, and 3) recovery of standard samples from a whole‐blood matrix. We found that reaction conditions of a mixture of acetonitrile and HEPES buffer (50 mM pH 8) gave rapid, clean conversion of sulfide to sulfide‐dibimane in the presence of excess monobromobimane. For whole blood, a 1:1:1 reaction mixture of 200 μl each acetonitrile:HEPES:blood proved optimal. Using this protocol, standard samples were consistently recovered in approximately 76% yield over the range of the assay. Baseline levels of free sulfide in rat blood were found to be about 0.3 – 0.5 μM. Subsequent work has proved the method effective in generating whole‐blood sulfide PK data in multiple species.
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A five carbon linear chain diamine, cadaverine (1,5-diaminopentane), is an important platform chemical having many applications in chemical industry. Bio-based production of cadaverine from renewable feedstock is a promising and sustainable alternative to the petroleum-based chemical synthesis. Here, we report development of a metabolically engineered strain of Escherichia coli that overproduces cadaverine in glucose mineral salts medium. First, cadaverine degradation and utilization pathways were inactivated. Next, L-lysine decarboxylase, which converts L-lysine directly to cadaverine, was amplified by plasmid-based overexpression of the cadA gene under the strong tac promoter. Furthermore, the L-lysine biosynthetic pool was increased by the overexpression of the dapA gene encoding dihydrodipicolinate synthase through the replacement of the native promoter with the strong trc promoter in the genome. The final engineered strain was able to produce 9.61 g L(-1) of cadaverine with a productivity of 0.32 g L(-1) h(-1) by fed-batch cultivation. The strategy reported here should be useful for the bio-based production of cadaverine from renewable resources.
Lysine decarboxylase
Metabolic Engineering
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Carbonyl sulfide
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Cadaverine was found in bacteriophage T4 when the host cells of Escherichia coli K-12 were grown in complex media and aerated by agitation. Only traces of cadaverine were found if the host was grown and agitated in synthetic medium or was aerated by vigorous bubbling in a complex medium. When the host cells were grown anaerobically in a complex medium, cadaverine became the major polyamine in the progeny phage. The polyamine content comprised 80% cadaverine, 14% spermidine (or its recently discovered homologue, N-3-aminopropyl-1, 5-diaminopentane), and the remainder putrescine. The conditions that favored appearance of cadaverine are known to be required for induction of lysine decarboxylase. It was shown that lysine was the sole source of bacterial cadaverine.
Lysine decarboxylase
Polyamine
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Polyamine content in testes of various vertebrates was studied extensively. Putrescine, spermidine and spermine were detected in all the animals examined, although the distribution pattern varied greatly from animal to animal. Cadaverine was detected only in amphibian testes; sym-homospermidine was found not only in testes but also in various other tissues of amphibians and of some reptiles.In the newt testis the concentration of cadaverine was lower than that of any other polyamines in summer, but there was a great increase in cadaverine content from autumn to winter. The testicular content of cadaverine was greater than that of other polyamines in winter. There was a gradual decrease in the cadaverine content in spring. The spermidine and spermine levels, which were rather low in winter, increased in spring and reached a peak in summer when spermatogenesis was active. The testicular concentration of putrescine that was much higher than that of spermidine or spermine throughout the year, increased only a little in summer. There was a significant negative correlation between the cadaverine levels and four other polyamine levels. Exogenous cadaverine decreased the testicular levels of putrescine. Mammalian gonadotropins decreased the cadaverine levels and increased the levels of other polyamines. A partially purified LH fraction from pituitaries of bullfrog, Rana catesbeiana, was also potent in depleting cadaverine of the testes of newts kept at 8°C. These results suggest that testicular cadaverine suppresses the biosynthesis of polyamines, especially spermidine and spermine which are closely associated with spermatogenesis.
Polyamine
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Cotyledon
Lysine decarboxylase
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A five carbon linear chain diamine, cadaverine (1,5-diaminopentane), is an important platform chemical having many applications in chemical industry. Bio-based production of cadaverine from renewable feedstock is a promising and sustainable alternative to the petroleum-based chemical synthesis. Here, we report development of a metabolically engineered strain of Escherichia coli that overproduces cadaverine in glucose mineral salts medium. First, cadaverine degradation and utilization pathways were inactivated. Next, L-lysine decarboxylase, which converts L-lysine directly to cadaverine, was amplified by plasmid-based overexpression of the cadA gene under the strong tac promoter. Furthermore, the L-lysine biosynthetic pool was increased by the overexpression of the dapA gene encoding dihydrodipicolinate synthase through the replacement of the native promoter with the strong trc promoter in the genome. The final engineered strain was able to produce 9.61 g L(-1) of cadaverine with a productivity of 0.32 g L(-1) h(-1) by fed-batch cultivation. The strategy reported here should be useful for the bio-based production of cadaverine from renewable resources.
Lysine decarboxylase
Metabolic Engineering
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Bacterial numbers, putrescine and cadaverine concentrations and pH were measured at regular intervals during the chill storage of vacuum packed beef. Odours on opening the packs were also assessed. Cadaverine concentration increased more rapidly than that of putrescine and measurable increases were evident before maximum bacterial numbers were attained and before any permanent off‐odours were detected. Diamine concentrations correlated better with total viable count (TVC) than with counts of Gram negative organisms.
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Tyramine
Biogenic amine
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