Phycoerythrocyanin
Encyclopedia
Phycoerythrocyanin is a kind of phycobiliproteins, magenta chromoprotein involved in photosynthesis of some Cyanobacteria. This chromoprotein consists of alpha- and beta-subunits, generally aggregated as hexamer. Alpha-phycoerythrocyanin contains a phycoviolobilin, a violet bilin, that covalently attached at Cys-84, and beta-phycoerythrocyanin contains two phycocyanobilins, a blue bilin, that covalently attached at Cys-84 and -155, respectively. Phycoerythrocyanin is similar to phycocyanin
, an important component of the light-harvesting complex (phycobilisome
) of cyanobacteria and red algae.
While only phycocyanobilin is covalently bound to phycocyanin
, leading to an absorption maximum around 620 nm, phycoerythrocyanin containing both phycoviolobilin and phycocyanobilin leads to an absorption maximum around 575 nm. As both phycoerythrocyanin and phycocyanin have phycocyanobilin acting as the terminal acceptor of energy transfer, they fluoresce around 635 nm, which is absorbed by allophycocyanins that have maximal absorption around 650 nm and maximal fluorescence around 670 nm. Finally, the light energy absorbed by phycoerythrocyanin is transferred to photosynthetic reaction center.
Phycocyanin
Phycocyanin is a pigment from the light-harvesting phycobiliprotein family, along with allophycocyanin and phycoerythrin. It is an accessory pigment to chlorophyll. All phycobiliproteins are water-soluble and therefore cannot exist within the membrane as do carotenoids, but aggregate forming...
, an important component of the light-harvesting complex (phycobilisome
Phycobilisome
Phycobilisomes are light harvesting antennae of photosystem II in cyanobacteria, red algae and glaucophytes.- General structure :Phycobilisomes are protein complexes anchored to thylakoid membranes. They are made of stacks of chromophorylated proteins, the phycobiliproteins, and their associated...
) of cyanobacteria and red algae.
While only phycocyanobilin is covalently bound to phycocyanin
Phycocyanin
Phycocyanin is a pigment from the light-harvesting phycobiliprotein family, along with allophycocyanin and phycoerythrin. It is an accessory pigment to chlorophyll. All phycobiliproteins are water-soluble and therefore cannot exist within the membrane as do carotenoids, but aggregate forming...
, leading to an absorption maximum around 620 nm, phycoerythrocyanin containing both phycoviolobilin and phycocyanobilin leads to an absorption maximum around 575 nm. As both phycoerythrocyanin and phycocyanin have phycocyanobilin acting as the terminal acceptor of energy transfer, they fluoresce around 635 nm, which is absorbed by allophycocyanins that have maximal absorption around 650 nm and maximal fluorescence around 670 nm. Finally, the light energy absorbed by phycoerythrocyanin is transferred to photosynthetic reaction center.