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- Tonning, E, et al.
(författare)
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Chemometric exploration of an amperometric biosensor array for fast determination of wastewater quality
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 21:4, s. 608-617
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Tidskriftsartikel (refereegranskat)abstract
- Four wastewater samples of different treatment qualities; untreated, alarm, alert and normal, from a Swedish chen-ti-thermo-mechanical pulp mill and pure water were investigated using an amperometric bioelectronic tongue in a batch cell. The aim was to explore enzymatically modified screen-printed amperometric sensors for the discrimination of wastewater quality and to counteract the inherent drift. Seven out of eight platinum electrodes on the array were modified with four different enzymes; tyrosinase, horseradish peroxidase, acetyl cholinesterase and butyryl cholinesterase. At a constant potential the current intensity on each sensor was measured for 200s, 100s before injection and 100s after injection of the sample. The dynamic biosensor response curves from the eight sensors were used for principal component analysis (PCA). A simple baseline and sensitivity correction equivalent to multiplicative drift correction (MDC), using steady state intensities of reference sample (catechol) recordings, was employed. A clear pattern emerged in perfect agreement with prior knowledge of the samples explaining 97% of the variation in the data by two principal components (PCs). The first PC described the treatment quality of the samples and the second PC described the difference between treated and untreated samples. Horseradish peroxidase and pure platinum sensors were found to be the determinant sensors, while the rest did not contribute much to the discrimination. The wastewater samples were characterized by the chemical oxygen demand (COD), biological oxygen demand (BOD), total organic carbon (TOC), inhibition of nitrification, inhibition of respiration and toxicity towards Vibrio fischeri using Microtox (R), the freshwater alga Pseudokirchneriella subcapita and the freshwater crustacean Daphnia magna. (c) 2005 Elsevier B.V. All rights reserved.
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- Valencia-Sanchez, M. I., et al.
(författare)
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Structural Insights into the Polyphyletic Origins of Glycyl tRNA Synthetases
- 2016
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 291:28, s. 14430-14446
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Tidskriftsartikel (refereegranskat)abstract
- Glycyl tRNA synthetase (GlyRS) provides a unique case among class II aminoacyl tRNA synthetases, with two clearly widespread types of enzymes: a dimeric ((2)) species present in some bacteria, archaea, and eukaryotes; and a heterotetrameric form ((22)) present in most bacteria. Although the differences between both types of GlyRS at the anticodon binding domain level are evident, the extent and implications of the variations in the catalytic domain have not been described, and it is unclear whether the mechanism of amino acid recognition is also dissimilar. Here, we show that the -subunit of the (22) GlyRS from the bacterium Aquifex aeolicus is able to perform the first step of the aminoacylation reaction, which involves the activation of the amino acid with ATP. The crystal structure of the -subunit in the complex with an analog of glycyl adenylate at 2.8 angstrom resolution presents a conformational arrangement that properly positions the cognate amino acid. This work shows that glycine is recognized by a subset of different residues in the two types of GlyRS. A structural and sequence analysis of class II catalytic domains shows that bacterial GlyRS is closely related to alanyl tRNA synthetase, which led us to define a new subclassification of these ancient enzymes and to propose an evolutionary path of (22) GlyRS, convergent with (2) GlyRS and divergent from AlaRS, thus providing a possible explanation for the puzzling existence of two proteins sharing the same fold and function but not a common ancestor.
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