ABSTRACT
A photobiological reaction entails the absorption of a specific wavelength of light by the functioning photoreceptor (photoacceptor) molecule. The identification of primary photoacceptor or photoacceptors is a central problem in photobiology. The complicated shape of the action spectra suggests that here the photoacceptor might be a set of interrelated molecules. Thus, a comparison between our action spectra and absorption spectra of respiratory chain components does not exclude the possibility for some of the respiratory chain components being primary photoacceptors for light-growth responses. Dichromatic irradiation experiments can give the answer to question if photoacceptor molecules are photoreversible pigments. The possibility that the terminal oxidase of respiratory chain is the primary photoacceptor for increased ATP synthesis effect by irradiation with red light was proposed earlier by Kato et al. The data of dichromatic irradiation experiments indicate the photoacceptor in both procaryotic and eucaryotic cells being a set of functionally connected with each other molecules.
