Time-resolved polarized fluorescence of c-phycocyanin and its subunits from mastigocladus laminosus*

Abstract

The influence of aggregation and temperature on the excited state kinetics of C-phycocyanin from Mastiqocladus laminosus has been studied. Polarized fluorescence decay curves have been recorded using a synchronously pumped dye laserin conjunction with a synchroscan streak camera. The experimental data for all samples can be fit satisfactorily assuming a biexponential decay law. Fluorescence depolarization times have been interpreted in terms of energy transfer among the different chromophores. The influence of temperature is only moderate on the intramolecular relaxation, but pronounced on the rates of energy transfer. Both are dependent on the size of the aggregate. The biexponential decay of the α-subunit containing only one Chromophore, indicates the presence of different subsets of chromophores in these samples. The results are discussed in terms of variations of the chromophore arrangements upon temperature induced changes inthe protein conformation. © 1984, Walter de Gruyter. All rights reserved.