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EC 7.1.1.6 Details
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EC number
7.1.1.6
Accepted name
plastoquinol—plastocyanin reductase
Reaction
plastoquinol + 2 oxidized plastocyanin + 2 H+[side 1] = plastoquinone + 2 reduced plastocyanin + 4 H+[side 2]
Other name(s)
plastoquinol/plastocyanin oxidoreductase, cytochrome f/b6 complex, cytochrome b6f complex
Systematic name
plastoquinol:oxidized-plastocyanin oxidoreductase
CAS registry number
79079-13-3
Comment
Contains two b-type cytochromes, two c-type cytochromes (cn and f), and a [2Fe-2S] Rieske cluster. The enzyme plays a key role in photosynthesis, transferring electrons from photosystem II (EC 1.10.3.9) to photosystem I (EC 1.97.1.12). Cytochrome c-552 can act as acceptor instead of plastocyanin, but more slowly. In chloroplasts, protons are translocated through the thylakoid membrane from the stroma to the lumen. The mechanism occurs through the Q cycle as in EC 7.1.1.8, quinol—cytochrome-c reductase (complex III) and involves electron bifurcation.
History
created 1984 as EC 1.10.99.1, transferred 2011 to EC 1.10.9.1, transferred 2018 to EC 7.1.1.6