CALCULATION OF THE ELECTRON-AFFINITIES OF THE CHROMOPHORES INVOLVED IN PHOTOSYNTHESIS

We examine the electron affinities (EA) of the postulated electron acc eptor chromophores of the photosynthetic reaction center in R. Viridis . We estimate a difference of EA's between bacteriochlorophyll-b and b acteriopheophytin-b of 0.19 eV, in excellent agreement with the experi mental value reported at 0.20 eV, We estimate this difference in situ at 0.42 eV, compared to an experimental estimate of 0.34 eV. These res ults support those of Thompson and Zerner (J. Am. Chem. Sec. 1991, 113 , 8210) that in the absence of specific interactions between BChl-L-si de and the environment, electron transfer to BChl-L-side might not be directly involved in the overall electron transfer process.