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Phycocyanin: There are 2 extra helices not found in normal globins (gray). These helices mediate the dimeric interaction. The other helices are colored by group, N-terminus blue. The spacefilling group (Phycocyanobilin) occupies a position similar to the heme in myoglobin. Phycocyanin is a bacterial or plant protein involved in photosynthesis. Comparison of phycocyanin with myoglobin: The phycocyanin is reloaded Both phycocyanin and myoglobin (sperm whale) are now both loaded Alignment: The 2 proteins are aligned along their alpha carbons Similarity of the proteins :The proteins are converted to a cartoons view and the myoglobin heme is shown. The Phycocyanobilin would occupy the same space in phycocyanin. The alignment of the two proteins shows how similar they are, even though the amino acid sequence has diverged significantly. Myoglobin is colored light blue, while Phycocyanin is white Brejc, K., Ficner, R., Huber, R., Steinbacher, S.: Isolation, crystallization, crystal structure analysis and refinement of allophycocyanin from the cyanobacterium Spirulina platensis at 2.3 A resolution. J Mol Biol 249 pp. 424 (1995) (PubMed) 1all (PDB) |