Primary Acceptor - The electron from P870 is received by an intermediate acceptor (I) and transferred to a primary acceptor (X). The exact nature of the acceptor is not known. The purified P870 reaction centre has been shown to contain nonhaeme iron and ubiquinone.
This has led, to the suggestion that one of these substances, or possibly both, act as primary acceptors. X is therefore likely to be an iron-sulphur (Fe-S) protein or anifon-quinone complex. It mayor may not be ferredoxin.
