Identification of chlorophyll b in extracts of prokaryotic algae by fluorescence spectroscopy.

Abstract

Solvent extracts of 3 different prokaryotic algae from 3 spp. of didemnid ascidians [Diplosoma virens, Trididemnum cyclops and Didemnum ternatanum] contained pigments identified, on the basis of their fluorescence excitation (E) and fluorescence emission (F) spectral maxima (measured in nm) at 77.degree. K, as chlorophyll a (E 449, F 678) and chlorophyll b (E 478, F 658). The release of algae on cutting or freezing D. virens was accompanied by a strong unidentified acid that converted these pigments to pheophytins. This unexpected finding provided further confirmation of the identity of the chlorophylls on the basis of the fluorescence spectra at 77.degree. K of pheophytin a (E 415, F 669) and phenophytin b (E 439, F 655). There was no evidence for the presence of the fluorescent bilin pigments found in other prokaryotic blue-green algae. Chlorophyll a/b ratios ranged from 2.6-12.0 in algae from different ascidians. The photosynthetic membranes were not organized into appressed thylakoids or grana in the algae from any of the 3 spp. of ascidians. The relationship between these observations and those in higher eukaryotic organisms is discussed.