The secondary electron acceptors of photosystem Ι in Acaryochloris marina and Gloeobacter violaceus PCC7471

Abstract

The secondary electron acceptor of photosystem(PS) Ι in a cyanobacterium Groeobacter violaceus PCC7421 was identified as menaquinone-4(MQ-4) by HPLC, absorption and mass analyses[1]. MQ-4 was the sole quinone detected in PSΙ complexes of G. violaceus. The MQ-4 content in the PSΙ complexes was estimated to be two on the basis of Chl a' / P700=1, indicating that MQ-4 functions as A₁ in the PSΙ complexes of G. violaceus.
The secondary electron acceptor of photosystem(PS) Ι in Acaryochloris marina was identified as phylloquinone(PhQ) by HPLC and absorption analyses. Further studies are now under way.

[1] M. Mimuro et al., (2005) FEBS Letters, 579, 3493-3496.