Energy transfer and site of energy trapping in photosystem I.

Studies of mutants of Chlamydomonas reinhardi deficient in the chlorophyll . protein complex CP1 show that energy transfer occurs between at least three Photosystem I units. Evidence for the connection of the Photosystem I units is also obtained by studying their optical cross-section in wild-type cells in which a fraction of the Photosystem I centers are inactivated. The site of energy trapping in the Photosystem I unit is shown to be the photochemical center itself and not the surrounding long-wavelength absorbing forms of chlorophyll.