[Study of energy migration between native forms of chlorophyll at -196 degrees C by the method of sensitized fluorescence]

Abstract

Mathematical decomposition of fluorescence spectra of chloroplasts and cells measured under monochromatic excitation in the regions of absorption maxima of the main native forms allowed the authors to calculate the efficiency of energy migration between forms. It is shown that 80--100% of absorbed quanta flow to the Chl 738/708 form (bean) in photosystem 1, whereas in photosystem 2, the Chl 695/690 and Chl 703/698 forms are terminal energy acceptors. Efficient backward energy transfer between the Chl 680/676 and Chl 686/682 forms and the existence of energy migration pathways passing one or two steps of the energy stairway formed by the energy levels of the chlorophyll forms are found. It is shown that chlorphyll b is not an intermediate link in the process of energy transfer from carotenoids to chlorophyll a. The intrinsic fluoresence quantum yields of the native forms are calculated.