Ca2D Binding and Transport: A Novel Function for Coenzyme Q

Bogeski, Ivan and Gulaboski, Rubin and Mirceski, Valentin and Reinhard, Kappl and Hoth, Markus (2011) Ca2D Binding and Transport: A Novel Function for Coenzyme Q. In: Symposium 18: The Alternating Access Mechanism in the Era of Transporter Structures, 7-11 March, Baltimore, USA.

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Coenzyme Q10 (CoQ10) is one of the essential components of the mitochondrial
electron-transport chain (ETC) with a primary function to transfer electrons
along and protons across the inner mitochondrial membrane (IMM).
The concomitant proton gradient across the IMM is essential for the process
of oxidative phosphorylation and consequently ATP production.
We report that CoQ10 and its analog CoQ1 have an as-of-yet unknown potential
in Ca2þ binding and transport. Using voltammetry, UV-VIS spectrometry,
electron paramagnetic resonance (EPR) and nuclear magnetic resonance
(NMR) we show that the native form of both CoQ10 and its analog CoQ1 neither
bind nor transport Ca2þ ions. However, when exposed to alkaline media or
monoxygenase enzymes such as cytochrome P450, both CoQs undergo structural
changes through a complex reaction pathway and form quinone structures
with distinct properties. In a time dependent manner, one or both methoxy
groups at position 2 and 3 on the quinone ring are replaced by a hydroxyl group.
Contrary to the native form, the new hydroxylated products (of CoQ1 or
CoQ10), depending on its redox transformation, are effectively chelating and
transporting Ca2þ across artificial biomimetic membranes.
Our results open new perspectives about the physiological importance of
CoQ10, not only as electron and proton transporter, but also as a potential regulator
of mitochondrial Ca2þ homeostasis.

Item Type: Conference or Workshop Item (Poster)
Subjects: Natural sciences > Biological sciences
Natural sciences > Chemical sciences
Natural sciences > Physical sciences
Divisions: Faculty of Agriculture
Depositing User: Rubin Gulaboski
Date Deposited: 18 Nov 2012 21:30
Last Modified: 18 Nov 2012 21:30

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