4-oxo-4H-quinolizine-3-carboxylic acids as Mg2+ selective, fluorescent indicators.
In this paper, we present the synthesis of a new series of substituted 4-oxo-4H-quinolizine-3-carboxylic acids and the evaluation of their fluorescent response upon complexation with Mg2+ and Ca2+. This has led to the development of the first Mg2+-selective, ratioable fluorescent indicators. We found that 4-oxo-4H-quinolizine-3-carboxylates are excellent fluorophores which show a strong fluorescent response to Mg2+ but not to Ca2; the latter metal ion often causing interference during Mg2+ measurements with previously described indicators. The dissociation constants of the studied fluorophores-around 1.0 mM-are of the same order of magnitude as is usually observed for intracellular Mg2+.
Otten
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National Institute of Environmental Health Sciences, Laboratory of Structural Biology, P.O. Box 12233, MR-03, RTP, North Carolina 27709, USA.
London
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Levy
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D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D002264:Carboxylic Acids / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D011807:Quinolizines / Q000737:chemistry*; D013057:Spectrum Analysis
D002264:Carboxylic Acids; D005456:Fluorescent Dyes; D011807:Quinolizines; D008274:Magnesium; D002118:Calcium