NOTPME: A31P NMR probe for measurementof divalent cations in biological systems
- 11 March 1991
- journal article
- Published by Wiley in FEBS Letters
- Vol. 280 (1), 121-124
- https://doi.org/10.1016/0014-5793(91)80218-r
Abstract
1, 4, 7-Triazacyclononame-N, N′,N′-tris(methylenephosphonate monoethylester) (NOTPME) has been synthesized, characterized and analyzed for use as a 31P NMR indicator of intracellular Mg2+ and Zn2+ ions. The 31P NMR spectrum of this chelate in the presence of metal ions shows characteristics resonances for the free chelate, Mg(NOTPME)−, Zn(NOTPME)− and Ca(NOTPME)−. The K??? values indicate that this chelate has a 10-fold higher affinity for Mg2+ than for Ca2+ at physiological pH values. In the presence of Mg2+, NOTPME is readily loaded into red blood cells. A 31P NMR spectrum of red cells taken after several washing shows resonances characteristics of entrapped NOTPME and the Mg(NOTPME)− complex, the relative areas of which report an intracellular free Mg2+ concentration of 0.32 mM. The 31P chemical shifts of the free chelate and its metal complexes are far downfield from the typical phosphorus-containing metabolites observed in biological systems, thus making it possible to monitor intracellular cation concentration and cell energetics simultaneouslyKeywords
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