Flourescence Lifetime of the Information Processing Plant Pigment Phytochrome

Summary Fluorescence lifetime of buffered aqueous solutions of large phytochrome has been determined at room temperature using a laser phase fluorometer with subnanosecond resolution. By studying the decay characteristics in dependence on the wavelength of the fluorescence the decay time was found to decrease with increasing wavelength over the fluorescence band. At the wavelength of the fluorescence maximum (λ = 678 nm) and the modulation frequency of 78.4 MHz the effective lifetime was determined to be 0.4 us. Measurements of the effective fluorescence lifetime at different modulation frequencies indicate that the fluorescence decay is not single exponential.