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Semiquinones (or ubisemiquinones, if
their origin is ubiquinone) are free
radicals resulting from the
removal of one
hydrogen atom with its
electron during...
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exist in four
redox states,
which are the flavin-N(5)-oxide, quinone,
semiquinone, and hydroquinone. FAD is
converted between these states by accepting...
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neutral (
semiquinone) state, and
colourless when
totally reduced. The
oxidized and
reduced forms are in fast
equilibrium with the
semiquinone (radical)...
- protein' and to the bL heme. This
oxidation reaction produces a
transient semiquinone before complete oxidation to ubiquinone,
which then
leaves the Qo site...
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three redox states,
fully oxidized (ubiquinone),
partially reduced (
semiquinone or ubisemiquinone), and
fully reduced (ubiquinol). The
redox functions...
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first ubiquinol (now
oxidised to ubiquinone) is released,
whilst the
semiquinone remains bound.
Round 2: A
second ubiquinol is
bound by
cytochrome b....
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catalytic cycle, a
reversible interconversion of the
oxidized (FMN),
semiquinone (FMNH•), and
reduced (FMNH2)
forms occurs in the
various oxidoreductases...
- protons. In the
first step, a short-lived
semiquinone intermediate is formed. In the
second step, the
semiquinone is
reduced into a
quinone dianion. 9,10-Anthraquinone-2...
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convert to the
semiquinone radical. At pH = 7, this
conversion occurs at 100 mV:[citation needed] C6H4(OH)2 → C6H4(O)(OH) + ½ H2 The
semiquinone radical can...
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electron results in the free-radical (
semiquinone) form of Q, and
transfer of the
second electron reduces the
semiquinone form to the
ubiquinol form, QH2....
