Apparent Mg2+-adenosine 5-triphosphate dissociation constant measured with Mg2+ macroelectrodes under conditions pertinent to 31P NMR ionized magnesium determinations

Détails

ID Serval
serval:BIB_B581E0C3FACD
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Apparent Mg2+-adenosine 5-triphosphate dissociation constant measured with Mg2+ macroelectrodes under conditions pertinent to 31P NMR ionized magnesium determinations
Périodique
Analytical Biochemistry
Auteur(s)
Zhang  W., Truttmann  A. C., Luthi  D., McGuigan  J. A.
ISSN
0003-2697 (Print)
Statut éditorial
Publié
Date de publication
09/1997
Volume
251
Numéro
2
Pages
246-50
Notes
Journal Article --- Old month value: Sep 5
Résumé
Using Mg2+ macroelectrodes based on the sensor ETH 7025 and accurate Mg2+-EDTA buffer solutions, the apparent Mg2+-ATP dissociation constant (Kapp) was measured at 25 and 37 degrees C in background solutions mimicking the cationic intracellular milieu of muscle cells. The mean +/- SD (in microM) at 25 degrees C was 157.0 +/- 13 (n = 4), 127.5 +/- 12.0 (n = 11), 101.0 +/- 9.0 (n = 4) and at 37 degrees C was 106.6 +/- 9.6 (n = 4), 87.4 +/- 4.9 (n = 4), 78.1 +/- 2.0 (n = 4) at pH values of 6.7, 7.2, and 7.7, respectively. The dependence of Kapp at 25 degrees C on the ionic strength was also measured, the mean +/- SD (microM) being 61.9 +/- 2.2 (n = 3), 127.5 +/- 12 (n = 11), and 243.0 +/- 11.8 (n = 3) at ionic strengths of 0. 087, 0.156 (normal background), and 0.3 m, respectively. These values are larger than the Kapp values most commonly used in the literature (87.4 microM compared to 38 microM at pH 7.2 and 37 degrees C) to estimate the [Mg2+]i in 31P NMR experiments, attributed to the difficulties in setting the [Mg2+]i without the use of Mg2+ buffer solutions. If these new values are used, the literature values for [Mg2+]i estimated by 31P NMR increase by a factor of around 1.5, making them similar to values obtained by direct Mg2+ microelectrode measurements.
Mots-clé
Adenosine Triphosphate/*metabolism Animals Chlorides Electrodes Kinetics Magnesium/*metabolism Magnetic Resonance Spectroscopy Osmolar Concentration Solutions
Pubmed
Web of science
Création de la notice
28/01/2008 13:50
Dernière modification de la notice
20/08/2019 15:23
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