Spectroscopic properties of chlorophyll a in the water-soluble peridinin-chlorophylla-protein complexes (PCP) from the symbiotic dinoflagellate Symbiodinium microadriaticum

The spectroscopic characteristics of chlorophyll (Chl) a in two water- soluble peridinin-chlorophyll a-protein complexes (PCP), isolated from the symbiotic dinoflagellate Symbiodinium microadriaticum, were analyzed in the 600 to 750 nm wavelength range. Gaussian deconvolution analyses of the absorption spectra of monomeric and dimeric PCP recorded at 160 K demonstrate that the Chl a Qy envelope of both complexes contains two spectral forms. Similar results were obtained from the Gaussian deconvolution of the fluorescence emission spectra taken at 119 K. Analyses of the calculated fluorescence emission of the different spectral forms at room temperature shows close agreement with the results obtained from Gaussian deconvolution analyses of the fluorescence emission spectra. The evidence indicates that the emission spectra of the intact complexes are the result of independent emission of each spectral form. Analyses of the contribution of each spectral form to the primary maximum of the emission spectra as a function of temperature is also supportive of the existence of two spectral forms of Chl a.