Delayed Fluorescence of Chl d from Acaryochloris marina Photosystem II

Abstract

A.marina has chlorophyll d(Chl d) and a(Chl a) as major and minor pigments.
However, role of Chl d in Photosystem II (PSII) reaction center is not yet clear. We investigated delayed fluorescence (DF) emitted from PSII by charge recombination. DF in the millisecond time range showed emission peak at 720nm indicating emission from Chl d. DF in microsecond range also showed 720nm peak. No emission from Chl a was detected. DF excitation spectrum showed peaks at 630nm(Phycobilin) and 720nm(Chl d). Comparing with the absorption spectrum, apparent excitation efficiency of Chl d was calculated to 0.49 supporting that a half of Chl d resides in PSII. This result differs from the estimation in Synechocystis PCC6803 that less than 17% of Chl a resides in PSII.