Spectroelectrochemical study on the redox potential of the primary donor of Photosystem I in Acaryochloris marina

Abstract

Acaryochloris marina is a unique cyanobacterium that possesses chlorophyll d as a major photosynthetic pigment. The photosystem (PS) I and II of A. marina have been isolated and well characterized. The primary donor of PS I was assigned to Chl d/Chl d' heterodimer. The redox potential of the primary donor was reported as +335 mV (vs. SHE), which is lower by approximately 100 mV than those of the primary donor of photosystem I in other photosynthetic organisms; however this reported value has not yet been consistent with other experimental results (Benjamin et al, 2007; Telfer et al 2007). In the present study, we have tried to measure the redox potential of the primary donor of A. marina PS I with a spectroelectrochemical technique. We will compare the redox potentials of the primary donor of PS I in the various organisms including A. marina.