7.1.1.6
plastoquinol-plastocyanin reductase
:= BRENDA,
:= KEGG,
:= MetaCyc,
:= SABIO-RK
:= amino acid sequences
: The reaction catalyzed by EC-7.1.1.6 is achieved by the Q-cycle. The Q-cycle can be divided into two halves. In the first half, a molecule of Plastoquinols plastoquinol transfers its electrons via bifurcation to two acceptors: the first electron is transferred to Plastocyanin-Reduced, releasing a proton to the thylakoid lumen and forming a radical Semiplastoquinones semiplastoquinone. The semiquinone radical donates the second electron to cytochrome b6, where it is transferred to a different PLASTOQUINONE plastoquinone molecule, forming another semiplastoquinone radical. This sequence of events can be summarized by the following reaction: RXN-22952 In the second half of the cycle, another Plastoquinols plastoquinol is processed in a similar manner. It too transfers its electrons via bifurcation to Plastocyanin-Reduced, releasing a second proton to the thylakoid lumen and forming a radical Semiplastoquinones semiplastoquinone. This radical transfers the second electron to cytochrome b6. However, at this point the second cycle differs from the first one, since the second electron reaches the semiquinone that formed during the first half cycle, resulting in its reduction to Plastoquinols plastoquinolin a reaction that extracts two protons from the cytoplasmic side of the thylakoid membrane. This half cycle could be summarized as follows: TRANS-RXN-509
: NAD+ (ec 1.2.1.59, see R01061)
: NAD+ (ec 1.2.1.59, see R01061)
: NAD+ (ec 1.2.1.59, see R01061)
: NAD+ (ec 1.2.1.59, see R01061)
: multi-step reaction
: multi-step reaction (isomerization, carboxylation, hydration and cleavage)
: Methane metabolism,
: gluconeogenesis II (Methanobacterium thermoautotrophicum),
: Methane metabolism,
: gluconeogenesis II (Methanobacterium thermoautotrophicum),
: Carbon fixation in photosynthetic organisms,
: pentose phosphate pathway (non-oxidative branch) II,
: Carbon fixation in photosynthetic organisms,
: pentose phosphate pathway (non-oxidative branch) II,
: Pentose phosphate pathway,
: pentose phosphate pathway (non-oxidative branch) II,
: Pentose phosphate pathway,
: pentose phosphate pathway (non-oxidative branch) II,
: Glycolysis / Gluconeogenesis,
: gluconeogenesis II (Methanobacterium thermoautotrophicum),
: This is an alternative substrate reaction of E.C. 4.1.2.13.
: Glycolysis / Gluconeogenesis,
: glycolysis I (from glucose 6-phosphate),
: Glycolysis / Gluconeogenesis,
: glycolysis I (from glucose 6-phosphate),
: Pentose phosphate pathway,
: pentose phosphate pathway (non-oxidative branch) II,
: TPP-dependent enzyme (see R06863+R06861)
: Pentose phosphate pathway,
: pentose phosphate pathway (non-oxidative branch) II,
: TPP-dependent enzyme (see R06863+R06861)