抄録
A sensitive method for magnesium determination which utilized the fluorescence of magnesium-8-hydroxyquinoline complex made estimation of the magnesium binding constant of adenosine triphosphate possible to be carried out in solutions containing both adenosine triphosphate and magnesium ion in concent-rations as low as 10-5M. The constant for Mg2+-ATP4- was thus found to be 6-8×104 (M)-1 in 0.1M tris-(hydroxy)-methyl-amino-methane buffer (pH 8.0-8.3) and 3-5×104 (M)-1 in 0.1M triethanolamine buffer (pH 8.0-8.3) at 25°C.
The magnesium binding constants of ITP, ADP, pyrophosphate, orthophosphate, citrate, and oxalate were also estimated by the same method. It was then found that the constants for all the phosphate compounds tested were higher in Tris-buffer than in triethanolamine buffer but that the constants for citrate and oxalate were independent of the difference in buffer.
