数据之源，洞见之始

Plastoquinone 9 is found in anise. Plastoquinone 9 is a constituent of alfalfa and other plants

Plastochromenol-8

|FRAME: PLASTOQUINONE Plastoquinones| (PQ) are benzoquinone electron carriers that can function as acceptor/donor for either one or two electrons. They are analogs of |FRAME: Ubiquinones "ubiquinones"| (Coenzyme Q), with two methyl groups substituting the methoxy groups found in Q. The fully reduced form is called |FRAME: Plastoquinols|.Plastoquinones are found in the chloroplasts of higher plants, red, brown and green algae, and in cyanobacteria, and are important members of the photosynthetic electron transfer chain, where they carry electrons from |FRAME: CPLX490-3506| to the |FRAME: CPLX-9022|. In fact, it has been shown that in cyanobacteria essentially all electron transport through unbound quinones proceeds via PQ in cyanobacterial thylakoids. Apart from PQ the only quinone found in thylakoids is vitamin K1, which is associated with PS I |CITS: [Vermaas01]|.Plastoquinones also serve as cofactors involved in the desaturation of phytoene in the synthesis of carotenoids (see |FRAME: PWY-6475|).Plastoquinone was isolated originally in 1946 from alfalfa, but was not identified at the time. It was rediscovered in 1959 and its structure was described in the same year (see |CITS: [7022156]|).Please note that tyhe structure shown here is that of |FRAME: PLASTOQUINONE-9| and is not accurate for this generic class of compounds, which contains plastoquinones with different side-chain lengths.