Redox Chemistry of Ca-Transporter 2-Palmitoylhydroquinone in an Artificial Thin Organic Film Membrane

Mirceski, Valentin and Gulaboski, Rubin and Bogeski, Ivan and Hoth, Markus (2007) Redox Chemistry of Ca-Transporter 2-Palmitoylhydroquinone in an Artificial Thin Organic Film Membrane. Journal of Physical Chemistry C, 111 (16). pp. 6068-6076. ISSN 1932-7447

[thumbnail of pdf PUBLICATIONS_JPC2007-Ca-Quinone.pdf]
Text pdf PUBLICATIONS_JPC2007-Ca-Quinone.pdf

Download (393kB) | Preview


The redox chemistry of 2-palmitoylhydroquinone (H2Q), a recently introduced synthetic transmembrane Ca2+
transporter, was studied with cyclic and square-wave voltammetry in an artificial thin organic-film membrane
sandwiched between a pyrolytic graphite electrode and an aqueous solution. The membrane has a micrometer
dimension and consists of the water immiscible organic solvent nitrobenzene, which contains suitable electrolyte
and H2Q as a redox active compound. The potential drop at the electrode/membrane interface is controlled
by the potentiostat, whereas the potential drop at the membrane/water interface is dependent on the ClO4
concentration, which is present in a large excess in both liquid phases. The redox transformation of H2Q at
the electrode/membrane interface is accompanied by a corresponding ion-transfer reaction at the other side
of the membrane. Proton transfer at the membrane/water interface is critical for the redox transformation of
H2Q in the interior of the membrane, as a strong dependence of the voltammetric response on the pH of the
aqueous medium was observed. H2Q undergoes two oxidation processes due to existence of two distinctive
redox forms of H2Q. The electrochemical mechanism can be explained with two tautomer forms of H2Q
formed by migration of a proton between the 1-hydroxyl group and the adjacent carbonyl group of the palmitoyl
residue. Both tautomers undergo 2e/2H+ distinctive redox transformations to form the quinone form of the
studied compound. In the presence of Ca2+ in the aqueous phase, voltammetric experiments confirmed the
capability of both tautomers to form 1:1 complexes with Ca2+ and to extract it into the organic membrane.
Upon the oxidation of the complexes, Ca2+ is expelled back to the aqueous phase. The studied compound
exhibits very similar complexing affinity toward Mg2+, implying that it is not highly selective for transmembrane
Ca2+ transport.

Item Type: Article
Uncontrolled Keywords: calcium transporter, quinones, ion transfer, complexation, liquid-liquid interface, voltammetry
Subjects: Medical and Health Sciences > Basic medicine
Natural sciences > Biological sciences
Natural sciences > Chemical sciences
Natural sciences > Physical sciences
Divisions: Faculty of Agriculture
Depositing User: Rubin Gulaboski
Date Deposited: 31 Oct 2012 13:14
Last Modified: 15 Aug 2013 13:54

Actions (login required)

View Item View Item