Ramasamy R, Lazar I, Brucher E, Sherry A D, Malloy C R
Department of Chemistry, University of Texas at Dallas, Richardson 75083-0688.
FEBS Lett. 1991 Mar 11;280(1):121-4. doi: 10.1016/0014-5793(91)80218-r.
1,4,7-Triazacyclononane-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 characteristic resonances for the free chelate, Mg(NOTPME)-, Zn(NOTPME)-, and Ca(NOTPME)-. The Kd 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 washings shows resonances characteristic 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 concentrations and cell energetics simultaneously.
1,4,7-三氮杂环壬烷-N,N',N''-三（亚甲基膦酸单乙酯）（NOTPME）已被合成、表征并分析，用作细胞内镁离子（Mg2+）和锌离子（Zn2+）的31P核磁共振指示剂。该螯合物在金属离子存在下的31P核磁共振谱显示了游离螯合物、Mg(NOTPME)-、Zn(NOTPME)-和Ca(NOTPME)-的特征共振峰。解离常数（Kd）值表明，在生理pH值下，该螯合物对Mg2+的亲和力比对Ca2+高10倍。在Mg2+存在的情况下，NOTPME很容易被载入红细胞。多次洗涤后采集的红细胞的31P核磁共振谱显示了截留的NOTPME和Mg(NOTPME)-络合物的特征共振峰，其相对面积表明细胞内游离Mg2+浓度为0.32 mM。游离螯合物及其金属络合物的31P化学位移比生物系统中观察到的典型含磷代谢物的化学位移远在低场，因此可以同时监测细胞内阳离子浓度和细胞能量代谢。
