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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription factors are modular entities built up of discrete domains, some devoted to DNA binding and others permitting transcriptional modulation. The structure of DNA binding domains has been thoroughly investigated and structural classes clearly defined. In sharp contrast, the structural constraints put on transactivating regions, if any, are mostly unknown. Our investigations focus on ERM, a eukaryotic transcription factor of the ETS family. We have previously shown that ERM harbours two transactivating domains (TADs) with distinct functional features: AD1 lies in the first 72 amino acids of ERM, while AD2 sits in the last 62. Here we show that AD1 is a bona fide acidic TAD, for it activated transcription in yeast cells, while AD2 did not. AD1 contains a 20 amino acid stretch predicted to form an alpha-helix that is found unchanged in the related PEA3 and ER81 transcription factors. Circular dichroism analysis revealed that a 32 amino acid peptide encompassing this region is unstructured in water but folds into a helix when the hydrophobic solvent trifluoroethanol is added. The isolated helix was sufficient to activate transcription and mutations predicted to disrupt it dramatically affected AD1-driven transactivation, whereas mutations decreasing its acidity had more gentle effects. A phenylalanine residue within the helix was particularly sensitive to mutations. Finally, we observed that ERM bound TAFII60 via AD1 and bound TBP and TAFII40, presumably via other activation domains.
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PMID:The ETS family member ERM contains an alpha-helical acidic activation domain that contacts TAFII60. 935 52

A simple and efficient method for the determination of ultra-trace amounts of inorganic mercury (iHg) and methylmercury (MeHg) in waters and fish tissues was developed using a micro-column filled with polyaniline (PANI) coupled online to flow injection-chemical vapour generation-inductively coupled plasma mass spectrometry (FI-CVG-ICPMS) system. Preliminary studies indicated that inorganic and methyl mercury species could be separated on PANI column in two different speciation approaches. At pH <3, only iHg could be sorbed and almost no adsorption of MeHg was found (speciation procedure 1). If the sample solution pH is approximately 7, both MeHg and iHg species could be sorbed on the PANI column. Subsequently both the Hg species were selectively eluted with 2% HCl and a mixture of 2% HCl and 0.02% thiourea respectively (speciation procedure 2). The adsorption percentage of iHg on the PANI column was unchanged even with acidity of the sample solution increased to 6 mol L(-1). Therefore, an acidic solution (5 mol L(-1) HCl), used for ultra-sound assisted extraction of the mercury species from biological samples, was used directly to separate MeHg from iHg in the fish tissues (tuna fish ERM-CE 463, ERM-CE 464 and IAEA-350) by PANI column using speciation procedure 1. The determined values were in good agreement with certified values. Under optimal conditions, the limits of detection (LODs) were 2.52 pg and 3.24 pg for iHg and MeHg (as Hg) respectively. The developed method was applied successfully to the direct determination of iHg and MeHg in various waters (tap water, lake water, ground water and sea-water) and the recoveries for the spiked samples were in the range of 96-102% for both the Hg species.
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PMID:On-line speciation of inorganic and methyl mercury in waters and fish tissues using polyaniline micro-column and flow injection-chemical vapour generation-inductively coupled plasma mass spectrometry (FI-CVG-ICPMS). 2018 47

An acid microwave closed vessel digestion method was used for the determination of inorganic contaminants (Sb, As, Pb, Cd, Cr, Co, Cu, Ni and Hg) in polyamide raw materials (pellets) and textiles by inductively coupled plasma optical emission spectrometry (ICP OES). The initial tests were carried out with samples of polyamide pellets, which is the main raw material used to manufacture sport textiles. The recovery factors obtained were 94.4-105.7% with relative standard deviation (RSD) of 0.5-2.2%. The proposed method was evaluated by addition and recovery tests and also using certified reference materials (ERM-BCR680 and ERM-BCR681) showing good accuracy. The residual acidity was about 4% HNO(3) (w/w) and the quantification limits were from 0.1 to 6.6 mg kg(-1). After the development of these parameters for the raw material, the method was applied to textile samples from different sport fabrics obtained from three different brands. The residual carbon after sample digestion was 0.2% (w/w) and the most significant result was obtained for chromium, 901 mg kg(-1), in black fabric. Lixiviation tests using synthetic sweat and temperature were carried out on two black samples, showing that only 0.3% of the initial concentration migrated to the solution.
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PMID:Determination of inorganic contaminants in polyamide textiles used for manufacturing sport T-shirts. 2226 32