Fluorescence emission spectra at 77 K of pea and bean thylakoids. Emission spectra excited at 412 (A) and 470 nm (B) for pea (solid line) and bean (dashed line) thylakoids (10 μg Chl ml-1). Fluorescence emission-difference spectrum pea-minus-bean for samples excited at 412 (C) and 470 nm (D). The spectra (A, B) were normalized to the area of 100 under the spectrum, and the difference spectra (C, D) were calculated for the respective excitation spectra. The presented spectra are representative of three separate experiments.