ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract— Quantitative studies on the interactions of adenosine-triphosphate and several biogenic amines with magnesium ion have been carried out in an attempt to correlate the thermodynamic stabilities of the metal-binding of the amines with the in vivo affinities of the amines for granule-binding. Equilibrium data indicate that in each of the ternary chelate systems (viz. Mg2+-ATP-amine), the predominant reaction in the pH range 3.0–7.0 is the formation of a magnesium-ATP chelate with a stability constant, log KML=3.22 ± 0.02. Each of the biogenic amines coordinates with Mg2+-ATP system in the pH range 7.0–10.5 to form the mixed ligand chelate (or ternary chelate), Mg2+-ATP-amine(1:1:1). The stability constants for the binding of the amines with Mg2+-ATP are: (i) norepinephrine (NE) = 2.34 ± 0.32; (ii) epinephrine (E) = 2.95 ± 0.08; (iii) dopamine (DA) = 3.05 ± 0.06; (iv) octopamine (OA) = 1.93 ± 0.12; (v) 6-hydroxydopamine (6-HDA) = 2.42 ± 0.14; (vi) 3-methoxynorephedrine (MeN) =2.76 ± 0.09; (vii) amphetamine (AA) =2.09 ± 0.05; (viii) tyramine (TA) = 2.60 ± 0.04; (ix) phenylethylamine (PEA) = 0.A general correlation is indicated between the stability constants (binding strengths) of the amine chelates and the metal-binding functionalities of the amines on the one hand and their vesicular binding characteristics in in vivo systems on the other (Carlsson and Waldeck, 1966). The Mg2+-ATP-dependant amine storage mechanism of KIRSHNER (1962a;b) and Carlsson, Hillårp and Waldeck (1963) is discussed both in the light of the data on metal chelate stability and of a significant modification of metal coordination hypothesis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1972.tb01430.x
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