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Theoretical and experimental study of the complexation of valinomycin with ammonium cation
Author(s) -
Dybal Jiří,
Ehala Sille,
Kašička Václav,
Makrlík Emanuel
Publication year - 2008
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.21034
Subject(s) - valinomycin , chemistry , ionophore , hydrogen bond , ammonium , gramicidin , density functional theory , inorganic chemistry , electrolyte , computational chemistry , molecule , ion , membrane , organic chemistry , biochemistry , electrode
The interactions of valinomycin, macrocyclic depsipeptide antibiotic ionophore, with ammonium cation NH 4 + have been investigated. Using quantum mechanical density functional theory (DFT) calculations, the most probable structure of the valinomycin‐NH 4 + complex species was predicted. In this complex, the ammonium cation is bound partly by three strong hydrogen bonds to three ester carbonyl oxygen atoms of valinomycin and partly by somewhat weaker hydrogen bonds to the remaining three ester carbonyl groups of the valinomycin ligand. The strength of the valinomycin‐NH 4 + complex was evaluated experimentally by capillary affinity electrophoresis. From the dependence of valinomycin effective electrophoretic mobility on the ammonium ion concentration in the background electrolyte, the apparent binding (association, stability) constant ( K b ) of the valinomycin‐NH 4 + complex in methanol was evaluated as log K b = 1.52 ± 0.22. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1055–1060, 2008. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com