A macrocyclic reporter ligand for Mg2+: Analytical implications for clinical magnesium determinations

Ronald Corbett, Ana Batista, Abbot Laptook, A. Dean Sherry

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

A new approach is presented for measuring Mg in plasma using the macrocyclic reporter ligand, NOTMP (1, 4, 7-triazacyclononane- 1, 4, 7-tris (methylene methylphosphinate)) and 31P nuclear magnetic resonance spectroscopy (NMR). By virtue of its intermediate binding constant for Mg (Kd = 0.35 mM), measurements of Mg using NOTMP allows one to discriminate between Mg bound to the high and low affinity ligands present in plasma, when combined with more conventional measurements of Mg. We used this approach in conjunction with measurements of total Mg using atomic absorption spectroscopy (AAS) and ionized Mg using an ion selective electrode (ISE) to characterize the distribution of Mg in the plasma of 16 normal adults. The percentage of Mg distributed among high and low affinity ligands and in an ionized fraction was 31, 14 and 55 per cent respectively. Similar measurements on plasma following equilibrium dialysis suggest that the high and low affinity ligands in plasma correspond to high and low molecular weight compounds, respectively. Measurement of Mg by NOTMP, AAS and ISE were not affected by the storage of blood samples for up to 48 h at 4°C. The addition of MgSO4 to plasma and its subsequent analysis by these three methods suggests that the added Mg is primarily distributed among the high affinity ligands (mostly likely proteins) and ionized fractions. The approach presented here may offer novel insights into assessing the distribution of Mg in clinical samples.

Original languageEnglish (US)
Pages (from-to)79-88
Number of pages10
JournalMagnesium Research
Volume12
Issue number2
StatePublished - 1999

Fingerprint

Magnesium
Ligands
Plasmas
Ion-Selective Electrodes
Ion selective electrodes
Atomic spectroscopy
Absorption spectroscopy
Spectrum Analysis
Dialysis
Nuclear magnetic resonance spectroscopy
Blood
Magnetic Resonance Spectroscopy
Molecular Weight
Molecular weight
1,4,7-triazacyclononane-1,4,7-tris(methylene methylphosphinic acid)
Proteins

Keywords

  • p nmr
  • Blood
  • Macrocyclic ligands
  • Magnesium

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

A macrocyclic reporter ligand for Mg2+ : Analytical implications for clinical magnesium determinations. / Corbett, Ronald; Batista, Ana; Laptook, Abbot; Dean Sherry, A.

In: Magnesium Research, Vol. 12, No. 2, 1999, p. 79-88.

Research output: Contribution to journalArticle

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