Extraction of electron acceptor A1from pea photosystem I

Photosystem I particles were washed twice in either 0, 50 or 100% water‐saturated diethyl ether. It was found that the characteristic electron spin resonance signal associated with electron acceptor A 1 was progressively lost with increasing percentage saturation of the ether. Light‐induced electron flow to the terminal iron‐sulphur acceptors was inhibited although these acceptors were still present and could be chemically reduced. The kinetics of optical measurements of P700 + re‐reduction at 820 nm following ether washing were consistent with removal of electron acceptor A 1 .