Accessory pigment Accessory pigment Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll "a". They include other forms of this pigment, such as chlorophyll "b" in green algal and higher plant antennae, while other algae may contain chlorophyll "c" or "d". In addition, there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins, which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, in particular the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants. The large, physically associated group of chlorophylls and
Phycoerythrin Phycobiliproteins are part of huge light harvesting antennae protein complexes called phycobilisomes. In red algae they are anchored to the stromal side of thylakoid membranes of chloroplasts, whereas in cryptophytes phycobilisomes are reduced and (phycobiliprotein 545 PE545 molecules here) are densely packed inside the lumen of thylakoides. Phycoerythrin is an accessory pigment to the main chlorophyll pigments responsible for photosynthesis. The light energy is captured by phycoerythrin and is then passed on to the reaction centre chlorophyll pair, most of the time via the phycobiliproteins phycocyanin and allophycocyanin. Phycoerythrins except phycoerythrin 545 (PE545) are composed of (αβ) monomers assembled into