P-Phycoerythrin

The ORAC method was first proposed by Cao and co-workers in 1993. Like in the TRAP method, they used a fluorescent indicator. Determination of antioxidant activity by this method is based on measurement of decreasing fluorescence of the indicator caused by the radicals generated in the system. The reaction mixture in their proposal consisted of a fluorescent indicator p-phycoerythrin (p-PE), 2,2 -azobis(2-amidinopropane) dihydrochloride (AAPH) as a peroxyl radical generator and the analysed sample [42]. Attributing the low purity of p-phycoerythrin (approx. 30%) to the low reproducibility of fluorescence and the occurrence of different forms of phycoerythrin, Ou and co-workers [43] modified the method by replacing the indicator with fluorescein (3, 6 -dihydroxyspiro[isobenzofuran-l[3H],9 [9H]-xanthen]-3-one). 

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 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... 

Fig. 5.2. Methods for detection of passenger-ligand interaction. (A) Fluorophore-coupled ligand (B) fluorophore-coupled antibody (C) quaternary complex generated by subsequent rounds of incubation with ligand, primary antibody, biotinylated second antibody, and strep ta-vidin, R-phycoerythrin conjugate (D) quaternary complex generated by subsequent rounds of incubation wi tli ligand, primary antibody, biotinylated second antibody, and streptavidin-coated magnetobeads. L ligand P passenger.

Fig. 9. Absorption spectra of chlorophylls a and b, p-carotene, phycocyanin and phycoerythrin the overlaid spectrum (thick-line) is that of solar-energy distribution at earth s surface.

The two major polypeptides making up each phycobiliprotein are the so-called a- and p-subunits, with molecular weights of 17 and 18 kDa, respectively, and each consisting of 160-180 amino acids. Some phycobiliproteins, the phycoerythrins, contain an additional, 30-kDa y-subunit. 

Phycobilins phycoerythrin phycotyanin Natural food colorings Red and blue-green al e e.g., P. cruentum Natural source of pigmentation Borowdtzka, 1993 Roman et aL, 2002... 

Soni, B., Visavadiya, N. P., and Madamwar, D. (2008). Ameliorative action of cyanobacterial phycoerythrin on CC14-induced toxicity in rats. Toxicology 248,59-65. 

The compound C-phycoerythrin from marine cyanobacteria P. tenue NTDM05 isolated by a biosynthesis method was reported by Ah et al. (2012). The synthesis of CdS-NPs was subjected to UV-visible spectroscopy, Fourier transform infrared spectroscopy, EDAX, and transmission electron microscopy. The characterization results stated that synthesized CdS-NPs were an average size of 5 nm and its stability was identified using zeta potential. 

The effects of a broad spectrum of biliproteins extracted from different organisms were studied [12]. The biliproteins studied were C-phycocyanin from Phormidium luridum, Plectonema calothricoides and Anahaena variahilis phycoerythrin from Calothrix membranacea, Porphyridium cruentum and Phormidium persicinum phycocyanin from Chroomonas sp. and allophycocyanin from P. luridum. 

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