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Magnesium-25 nuclear magnetic resonance in aqueous phosphate solutions

1972; Elsevier BV; Volume: 6; Issue: 2 Linguagem: Inglês

10.1016/0022-2364(72)90123-0

1557-8968

Robert G. Bryant,

Solid-state spectroscopy and crystallography

Magnesium-25 nuclear magnetic resonance is studied in aqueous solutions of molecules containing phosphate groups which bind magnesium ion. The line width of magnesium ion in 1.5 M magnesium chloride solutions is 3.8 ± 0.5 Hz and is significantly broadened by the addition of phosphate-containing molecules such as ATP. The line broadening is shown to contain effects due to the nuclear electric quadrupole interaction as well as effects due to chemical exchange of the magnesium ion between complexed and uncomplexed sites in solution. The chemical exchange rate of magnesium ion with ATP is measured to be 2 × 10° sec−1 at 25°C, an ionic strength of 4.5 and pH of 7.9. The possibility of using magnesium-25 nuclear magnetic resonance to study magnesium ion interactions with enzymes is examined.