[Spectral effects of denaturation of B- and C-phycoerythrins]

B-phycoerythrin (B-PhE) from red alga Porphyridium cruentum and C-phycoerythrin (C-PhE) from blue-green alga Nostoc punctiforma were isolated. Their absorption and fluorescence spectra were measured at room and liquid nitrogen temperature. The drastic change of fluorescence and absorption maxima under dissociation of the proteins into subunits was observed. Dissociation of the C-PhE into two subunits (molecular weight 16 000 and 12 000) was revealed by SDS-acrylamide gel electrophoresis in 0.01% SDS solution at pH 7.0. The absorption spectra of subunits of both B-PhE and C-PhE were similar. The fluorescence quenching by oxidants and destructive photooxidation were negligible and increased after denaturation.