phycobilisomes การใช้

• In some cyanobacteria, the color of light influences the composition of phycobilisomes.
• There are many variations to the general phycobilisomes structure.
• Attached to the thylakoid membrane, phycobilisomes act as light-harvesting antennae for the photosystems.
• The relatively large distance between the thylakoids provides space for the external light harvesting antennae, the phycobilisomes.
• It is the only photoactive protein known to use a carotenoid as the light-harvesting antenna complexes of cyanobacteria, the phycobilisomes.
• Rhodoplasts have a double membrane with an intermembrane space and phycobilin pigments organized into phycobilisomes on the thylakoid membranes, preventing their thylakoids from stacking.
• They differ from glaucophyte and red algal chloroplasts in that they have lost their phycobilisomes, and contain chlorophyll " b " instead.
• They have lost their phycobilisomes and exchanged them for chlorophyll " c ", which isn't found in primary red algal chloroplasts themselves.
• "Prochlorococcus " is closely related to " Synechococcus, " another abundant photosynthetic cyanobacteria, which contains the light-harvesting antennae phycobilisomes.
• For his lucid, enthusiastic, informative, and gracefully written reviews explaining the structure and operation of phycobilisomes, the phycobiliprotein complexes that harvest light for photosynthesis in cyanobacteria.
• Their chloroplasts do not have phycobilisomes, but they do have phycobilin pigments which they keep in their thylakoid space, rather than anchored on the outside of their thylakoid membranes.
• Stanier's work on Cyanobacteria focused on obligate autotrophy, fatty acid composition, structure of phycobiliproteins and phycobilisomes, chromatic adaptation, nitrogen fixation, and their nutrition and taxonomy.
• Some groups of organisms contain more specialized light-harvesting structures ( e . g . phycobilisomes in Cyanobacteria and chlorosomes in Green sulfur and non-sulfur bacteria ), allowing for increased efficiency in light utilization.
• Phycobilins are a third group of pigments found in cyanobacteria, and glaucophyte, red algal, and Cryptophyte chloroplasts and some cyanobacteria don't have their phycobilin pigments organized into phycobilisomes, and keep them in their thylakoid space instead.
• Instead, the light-harvesting complexes ( also called phycobilisomes ), that consist of different proteins, sit on the inside of the proton gradient in " Gloeobacter " is created over the plasma membrane, where it forms over the thylakoid membrane in cyanobacteria and chloroplasts.
• In the ubiquitous marine cyanobacteria " Synechococcus ", the amount of phycourobilin in the phycobilisomes is correlated to the ecological niche the cells inhabit : offshore " Synechococcus " are quite phycourobililin-rich, while coastal " Synechococcus " contain very little or no phycourobilin.
• However, " Trichodesmium " utilises photosynthesis for nitrogen fixation by carrying out the Mehler reaction, during which the oxygen produced by PSII is reduced again after PSI . This regulation of photosynthesis for nitrogen fixation involves rapidly reversible coupling of their light-harvesting antenna, the phycobilisomes, with PSI and PSII.
• Therefore, their presence and the particular arrangement within the phycobilisomes allow absorption and unidirectional transfer of light energy to chlorophyll " a " of the photosystem II . In this way, the cells take advantage of the available wavelengths of light ( in the 500-650 nm range ), which are inaccessible to chlorophyll, and utilize their energy for photosynthesis.
• However, " Prochlorochoccus " has evolved to use a unique light-harvesting complex, consisting predominantly of divinyl derivatives of chlorophyll a ( Chl a2 ) and b ( Chl b2 ) and lacking monovinyl chlorophylls and phycobilisomes . " Prochlorococcus " is the only known wild-type oxygenic phototroph that does not contain Chl a as a major photosynthetic pigment, and is the only known prokaryote with ?-carotene.