Primary charge separation in the photosystem II core from Synechocystis: a comparison of femtosecond visible/midinfrared pump-probe spectra of wild-type and two P680 mutants.

ABSTRACT: It is now quite well accepted that charge separation in PS2 reaction centers starts predominantly from the accessory chlorophyll B(A) and not from the special pair P(680). To identify spectral signatures of B(A,) and to further clarify the process of primary charge separation, we compared the femtosecond-infrared pump-probe spectra of the wild-type (WT) PS2 core complex from the cyanobacterium Synechocystis sp. PCC 6803 with those of two mutants in which the histidine residue axially coordinated to P(B) (D2-His(197)) has been changed to Ala or Gln. By analogy with the structure of purple bacterial reaction centers, the mutated histidine is proposed to be indirectly H-bonded to the C(9)=O carbonyl of the putative primary donor B(A) through a water molecule. The constructed mutations are thu

SUBMITTER: Di Donato M 

PROVIDER: S-EPMC2397376 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature