Theoretical analysis of the enhancement effect in photosynthesis evidence for the "spill-over" model.

A quantitative examination of the "series" model of two distinct photosystems in photosynthesis is presented. Fractional absorptions and quantum yields of the two photosystems and energy transfer efficiency from photosystem II to photosystem I are introduced as parameters. Equations for the dependence of the enhancement functions and quantum yields on the wavelength are obtained. The predictions of the theory are compared to present literature data. There is, in general, an agreement of data to the form of the equations. Calculation of the energy transfer efficiency from photosystem II to photosystem I yields a significant value, ranging approximately from 0.5 to 1, in the different examples discussed, which include green, blue-green, and red algae. Inconsistency with data obtained in the presence of the inhibitor DCMU and its significance is also discussed.