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Rhett C. Smith - One of the best experts on this subject based on the ideXlab platform.
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dizinc phosphohydrolase model built on a m terphenyl scaffold and its use in indicator displacement assays for pyrophosphate under physiological conditions
European Journal of Organic Chemistry, 2009Co-Authors: Michael K. Coggins, Austa M. Parker, Anshuman Mangalum, Gabriela A. Galdamez, Rhett C. SmithAbstract:A dinucleating ligand {1,3-bis[2-(di-2-picolylaminomethyl)phenyl]benzene, L2} built on a m-terphenyl scaffold was prepared. The dissociation constants for the dizinc complex of L2 (Zn2L2) binding to phosphate, pyrophosphate and commercially available complexometric indicators were determined under physiological pH [10 mMN-(2-hydroxyethyl)piperazine-N′-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4]. Colorimetric and fluorescence-based indicator displacement assays with selectivity for pyrophosphate over other anions were achieved with Zn2L2 as the receptor component. These assays show good response characteristics for quantification of pyrophosphate concentrations as low as 2.5 × 10–6M, suggesting their utility for measuring pyrophosphate levels in synovial fluid. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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dizinc enzyme model complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions
Inorganic Chemistry, 2007Co-Authors: Brad P Morgan, Susan He, Rhett C. SmithAbstract:A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N‘-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator−Zn2L1 complexes, spanning 2 orders of magnitude from 2.8 × 10-4 M (alizarin red S) to 2.7 × 10-6 M (bromo pyrogallol red). Phosphate and pyrophosphate were tested for their ability to displace bound indicator and produce a detectable colorimetric response. Three indicators (bromo pyrogallol red, mordant blue 9, and zincon) complex to Zn2L1 to form an indicator displacement assay selective for pyrophosphate over phosphate. Because selection of an indicator/analyte pair having appropriate re...
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dizinc enzyme model complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions
Inorganic Chemistry, 2007Co-Authors: Brad P Morgan, Susan He, Rhett C. SmithAbstract:A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N‘-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator−Zn2L1 complexes, spanning 2 orders of magnitude from 2.8 × 10-4 M (alizarin red S) to 2.7 × 10-6 M (bromo pyrogallol red). Phosphate and pyrophosphate were tested for their ability to displace bound indicator and produce a detectable colorimetric response. Three indicators (bromo pyrogallol red, mordant blue 9, and zincon) complex to Zn2L1 to form an indicator displacement assay selective for pyrophosphate over phosphate. Because selection of an indicator/analyte pair having appropriate re...
Brad P Morgan - One of the best experts on this subject based on the ideXlab platform.
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dizinc enzyme model complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions
Inorganic Chemistry, 2007Co-Authors: Brad P Morgan, Susan He, Rhett C. SmithAbstract:A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N‘-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator−Zn2L1 complexes, spanning 2 orders of magnitude from 2.8 × 10-4 M (alizarin red S) to 2.7 × 10-6 M (bromo pyrogallol red). Phosphate and pyrophosphate were tested for their ability to displace bound indicator and produce a detectable colorimetric response. Three indicators (bromo pyrogallol red, mordant blue 9, and zincon) complex to Zn2L1 to form an indicator displacement assay selective for pyrophosphate over phosphate. Because selection of an indicator/analyte pair having appropriate re...
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dizinc enzyme model complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions
Inorganic Chemistry, 2007Co-Authors: Brad P Morgan, Susan He, Rhett C. SmithAbstract:A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N‘-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator−Zn2L1 complexes, spanning 2 orders of magnitude from 2.8 × 10-4 M (alizarin red S) to 2.7 × 10-6 M (bromo pyrogallol red). Phosphate and pyrophosphate were tested for their ability to displace bound indicator and produce a detectable colorimetric response. Three indicators (bromo pyrogallol red, mordant blue 9, and zincon) complex to Zn2L1 to form an indicator displacement assay selective for pyrophosphate over phosphate. Because selection of an indicator/analyte pair having appropriate re...
Frank Roesch - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic radiochemical and theoretical studies of the ga3 n 2 hydroxyethyl piperazine n 2 Ethanesulfonic Acid hepes buffer system evidence for the formation of ga3 hepes complexes in 68 ga labeling reactions
Contrast Media & Molecular Imaging, 2013Co-Authors: André F. Martins, M I M Prata, S P J Rodrigues, A Amorcoarasa, Carsten Burchardt, C Kroll, Patrick J Riss, Carlos F G C Geraldes, Frank RoeschAbstract:Recent reports have claimed a superior performance of HEPES buffer in comparison to alternative buffer systems for 67/68 Ga labeling in aqueous media. In this paper we report spectroscopic (1H and 71 Ga NMR), radiochemical, mass spectrometry and theoretical modeling studies on the Ga3+/HEPES system (HEPES = N-2-hydroxyethylpiperazine-N′-2-Ethanesulfonic Acid) performed with the aim of elucidating a potential contribution of HEPES in the 68/67 Ga radiolabeling process. Our results demonstrate that HEPES acts as a weakly but competitive chelator of Ga3+ and that this interaction depends on the relative Ga3+: HEPES concentration. A by-product formed in the labeling mixture has been identified as a [68 Ga]Ga(HEPES) complex via chromatographic comparison with the nonradioactive analog. The formation of this complex was verified to compete with [68 Ga]Ga(NOTA) complexation at low NOTA concentration. Putative chelation of Ga3+ by the hydroxyl and adjacent ring nitrogen of HEPES is proposed on the basis of 1H NMR shifts induced by Ga3+ and theoretical modeling studies. Copyright © 2013 John Wiley & Sons, Ltd.
Susan He - One of the best experts on this subject based on the ideXlab platform.
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dizinc enzyme model complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions
Inorganic Chemistry, 2007Co-Authors: Brad P Morgan, Susan He, Rhett C. SmithAbstract:A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N‘-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator−Zn2L1 complexes, spanning 2 orders of magnitude from 2.8 × 10-4 M (alizarin red S) to 2.7 × 10-6 M (bromo pyrogallol red). Phosphate and pyrophosphate were tested for their ability to displace bound indicator and produce a detectable colorimetric response. Three indicators (bromo pyrogallol red, mordant blue 9, and zincon) complex to Zn2L1 to form an indicator displacement assay selective for pyrophosphate over phosphate. Because selection of an indicator/analyte pair having appropriate re...
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dizinc enzyme model complexometric indicator pairs in indicator displacement assays for inorganic phosphates under physiological conditions
Inorganic Chemistry, 2007Co-Authors: Brad P Morgan, Susan He, Rhett C. SmithAbstract:A dizinc phosphohydrolase enzyme model complex employing the dinucleating ligand 2,6-bis-[(bis-pyridin-2-ylmethyl-amino)methyl]-4-methylphenol (L1) was tested for binding to a series of 11 commercially available complexometric indicators in aqueous N-2-hydroxyethylpiperazine-N‘-2-Ethanesulfonic Acid (HEPES) buffer at pH 7.4, with the aim of determining the applicability of these indicators in indicator displacement assays (IDAs) under physiological conditions. Dissociation constants (Kd) were determined for 11 indicator−Zn2L1 complexes, spanning 2 orders of magnitude from 2.8 × 10-4 M (alizarin red S) to 2.7 × 10-6 M (bromo pyrogallol red). Phosphate and pyrophosphate were tested for their ability to displace bound indicator and produce a detectable colorimetric response. Three indicators (bromo pyrogallol red, mordant blue 9, and zincon) complex to Zn2L1 to form an indicator displacement assay selective for pyrophosphate over phosphate. Because selection of an indicator/analyte pair having appropriate re...
A Amorcoarasa - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic radiochemical and theoretical studies of the ga3 n 2 hydroxyethyl piperazine n 2 Ethanesulfonic Acid hepes buffer system evidence for the formation of ga3 hepes complexes in 68 ga labeling reactions
Contrast Media & Molecular Imaging, 2013Co-Authors: André F. Martins, M I M Prata, S P J Rodrigues, A Amorcoarasa, Carsten Burchardt, C Kroll, Patrick J Riss, Carlos F G C Geraldes, Frank RoeschAbstract:Recent reports have claimed a superior performance of HEPES buffer in comparison to alternative buffer systems for 67/68 Ga labeling in aqueous media. In this paper we report spectroscopic (1H and 71 Ga NMR), radiochemical, mass spectrometry and theoretical modeling studies on the Ga3+/HEPES system (HEPES = N-2-hydroxyethylpiperazine-N′-2-Ethanesulfonic Acid) performed with the aim of elucidating a potential contribution of HEPES in the 68/67 Ga radiolabeling process. Our results demonstrate that HEPES acts as a weakly but competitive chelator of Ga3+ and that this interaction depends on the relative Ga3+: HEPES concentration. A by-product formed in the labeling mixture has been identified as a [68 Ga]Ga(HEPES) complex via chromatographic comparison with the nonradioactive analog. The formation of this complex was verified to compete with [68 Ga]Ga(NOTA) complexation at low NOTA concentration. Putative chelation of Ga3+ by the hydroxyl and adjacent ring nitrogen of HEPES is proposed on the basis of 1H NMR shifts induced by Ga3+ and theoretical modeling studies. Copyright © 2013 John Wiley & Sons, Ltd.