Phycocyanin/phycoerythrin

Phycobiliprotein allophycocyanin c-phycocyanin phycoerythrin Spirulina platensis Porphyridium sp. cancer prevention inflammation prevention anti-virus antioxidant properties neuroprotection 59, 60... 

Algae are classified according to their colors (1) Chlorophyceae (green), (2) Rhodophyceae (red), (3) Cyanophyceae (bine-green), and (4) Pheophyceae (brown). The major pigments inclnde chlorophylls a, b, and c, P-carotene, phycocyanin, xanthophylls, and phycoerythrin. All these pigments have great potential for applications in foods, pharmacenticals, and cosmetics. 

The red microalga Porphyridium aerugineum is a source of blue color. This species is different from other red microalgae in that it lacks red phycoerythrin and its phycocyanin is C-phycocyanin rather than the R-phycocyanin that accompanies phycoerythrin found in many red algae and in other Porphyridium species. However, the biochemicals produced by P. aerugineum are similar to those of other red microalgae, e.g., sulfated polysaccharides, carotenoids, and lipids. An alternative source of C-phycocyanin is Spirulina platensis. ... 

There are three main classes of phycobiliproteins, differing in their protein structure, bilin content, and fluorescent properties. These are phycoerythrin, phycocyanin, and allo-phycocyanin (APC). There are two main forms of phycoerythrin proteins commonly in use B-phycoerythrin isolated from Porphyridium cruentum and R-phycoerythrin from Gastroclonium coulteri. There also are three main forms of pigments found in these proteins phycoerythrobilin, phycourobilin, and phycocya no bilin (Glazer, 1985). The relative content of these pigments in the phycobiliproteins determines their spectral properties. All of them,... 

The spectral properties of four major phycobiliproteins used as fluorescent labels can be found in Tables 9.1 and 9.2. The bilin content of these proteins ranges from a low of four prosthetic groups in C-phycocyanin to the 34 groups of B- and R-phycoerythrin. Phycoerythrin derivatives, therefore, can be used to create the most intensely fluorescent probes possible using these proteins. The fluorescent yield of the most luminescent phycobiliprotein molecule is equivalent to about 30 fluoresceins or 100 rhodamine molecules. Streptavidin-phycoerythrin conjugates, for example, have been used to detect as little as 100 biotinylated antibodies bound to receptor proteins per cell (Zola et al., 1990). 

FIGURE 19-43 A phycobilisome. In these highly structured assemblies found in cyanobacteria and red algae, phycobilin pigments bound to specific proteins form complexes called phycoerythrin (PE), phycocyanin (PC), and allophycocyanin (AP). The energy of photons absorbed by PE or PC is conveyed through AP (a phycocyanobilin-binding protein) to chlorophyll a of the reaction center by exciton transfer, a process discussed in the text. 

I Peripheral plasma containing, chlorophyll, carotinoid, phycocyanin, and sometimes phycoerythrin.Class Cyanophyceae... 

There are three major classes of conjugated phyco-biliproteins,273/277 all of which are a(3 heterodimers often associated as (a(3)6 (Fig. 23-24). The allophyco-cyanins carry one bilin per subunit, the phycocyanins carry one on the a and two on the (t subunit, and the phycoerythrins carry two or three on the a subunit and three on the P (Fig. 23-24). Cysteine a-84 is one of the frequent attachment sites.273 Three-dimensional structures are known for several of these proteins278 281... 

In the PBS rods the phycobiliprotein hexamers can be identified by high-resolution electron microscopy as discs, subdivided into two halfs (a/3-trimers) of 30 A thickness [80,143]. Deeper insight into the molecular structure of the trimers and hexamers was achieved by X-ray crystallographic analyses of biliproteins. In the last century, strikingly coloured phycocyanin and phycoerythrin crystals had already been observed by Molish [144]. Recently, several C-phycocyanins [145-147], B-phycoerythrin [147,148] and phycoerythrocyanin [149] have been crystallized... 

Phycobiliproteins, such as phycocyanin and phycoerythrin, are members of a family of fluorescent accessory, nonchlorophyll-based pigments found in cyanobacteria and eukaryotic algae. The phycobiliproteins have characteristic broad absorption profiles spanning 450-600 nm, emissions ranging 570-660 nm, and small stokes shifts see Fig. 3. The major structural subunits, phycoerythrobilin (PEB) or phycocyanobilin... 

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