Phycoerythrocyanin and Phycoerythrin: Properties and Occurrence in Cyanobacteria

Abstract

A number of cyanobacterial phycoerythrocyanins were isolated and characterized with respect to spectroscopic properties and chromophore content. All were similar to the phycoerythrocyanin of Anabaena PCC 6411 and cross-reacted strongly with an antiserum prepared against that protein. The synthesis of phycoerythrocyanin was not controlled by a complementary chromatic adaptation mechanism in nine strains tested, but its synthesis appeared to be affected by light intensity. A survey of 240 strains of cyanobacteria revealed that no strain synthesized both phycoerythrocyanin and phycoerythrin and that phycoerythrocyanin was largely confined to those strains which can form heterocysts. Phycoerythrocyanin may be a taxonomically useful marker for certain strain clusters of this cyanobacterial grouping. Spectroscopic properties and chromophore compositions of several cyanobacterial phycoerythrins were also determined. At present, the ability to synthesize phycoerythrin and the capacity to exhibit complementary chromatic adaptation responses are widely distributed traits of limited taxonomic usefulness.