Abstract

Most of the light harvesting molecules of algae and cyanobacteria are located in phycobilisomes that are bound to the outer surface of the thylakoid membrane (1). The phycobilisomes of Synechococcus 6301 (S 6301) are composed of phycobiliproteins of mainly two kinds, namely C-phycocyanin (C-PC) and allophycocyanin (APC). The bilin prosthetic groups are open-chain tetrapyrroles bound to the apoprotein by a sulfur link (2). Glazer et al. (3,4) have determined the structure of phycobilisomes of S 6301 in some detail and it is known that C-PC forms hexamers that can add together in stacks or rods consisting of 1-7 hexameric units. Six such rods are then bound to a core of APC trimers. In this work we have used phycobilisomes from a mutant of S 6301 called AN 112, which has rods consisting of only one C-PC hexameric unit (5).

© 1984 Optical Society of America