Allophycocyanin: Difference between revisions
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<Structure load='1all' size='300' frame='true' align='right' caption='allophycocyanin' scene='Insert optional scene name here' /> | <Structure load='1all' size='300' frame='true' align='right' caption='allophycocyanin' scene='Insert optional scene name here' /> | ||
Allophycocyanin is a primarily <scene name='Allophycocyanin/2ndary_structure/2'>alpha-helical</scene> protein. It contains <scene name='Allophycocyanin/Subunits/2'>two subunits</scene>, which each have one phycocyanobilin. Allophycocyanin has a complex quaternary structure. First, trimers of the dimers form in a circular fashion, then stack on top of each other to form an antenna-like structure called the phycobilisome. | Allophycocyanin is a primarily <scene name='Allophycocyanin/2ndary_structure/2'>alpha-helical</scene> protein. It contains <scene name='Allophycocyanin/Subunits/2'>two subunits</scene>, which each have one phycocyanobilin. Allophycocyanin has a complex quaternary structure. First, <scene name='Allophycocyanin/Quaternary_structure/1'>trimers of the dimers</scene> form in a circular fashion, then <scene name='Allophycocyanin/Quaternary_structure_stack/1'>stack</scene> on top of each other to form an antenna-like structure called the phycobilisome. | ||
Allophycocyanin holds the <scene name='Allophycocyanin/Pigment/1'>pigment</scene> in place through a number of intermolecular interactions. A<scene name='Allophycocyanin/Asn73/1'>sn72</scene> forms hydrogen bonds with an amine in the pigment, while <scene name='Allophycocyanin/Arg86/1'>arginine 86</scene> interacts with a carboxylic acid that is exposed to the solvent. A key <scene name='Allophycocyanin/Asp87/2'>aspartic acid</scene> also holds the molecular planar. These interactions stabilize the pigment in the protein and hold the pigment planar. When the protein is unfolded, the | |||
Interestingly, the λmax of the chromophore can be tuned depending upon the protein binding it. For allophycocyanin, the λmax is 650 nm; in another phycobiliprotein, phycocyanin, the λmax is 625 nm, even though it uses the same chromophore. Phycocyanobilin is a highly flexible, linear tetrapyrrole that is covalently attached to the protein by a thiol linkage to a cysteine in the protein. | Interestingly, the λmax of the chromophore can be tuned depending upon the protein binding it. For allophycocyanin, the λmax is 650 nm; in another phycobiliprotein, phycocyanin, the λmax is 625 nm, even though it uses the same chromophore. Phycocyanobilin is a highly flexible, linear tetrapyrrole that is covalently attached to the protein by a thiol linkage to a cysteine in the protein. | ||
