Purification, Crystallization and Preliminary X-ray Diffraction Studies of C-Phycocyanin and Allophycocyanin fromSpirulina platensis

Abstract

C-phycocyanin and allophycocyanin from the green alga Spirulina platensis were isolated and crystallized by gel-acupuncture techniques. A novel two-step chromatographic procedure was used for purification. Blue hexagonal crystals were obtained by diffusing magnesium chloride into the protein solution for a week, followed by diffusion of PEG 6000 in order to complete the reduction of the solubility of the protein in the capillary tube used as a growth cell. In the case of allophycocyanin, crystals with a size of 0.4 × 0.3 × 0.3 mm were characterized by X-ray diffraction. They belong to space group P6322 with unit-cell parameters a-b--102.04, c = 131.22,A,. The crystals of C-phycocyanin belong to either space group P6 or P63 with unit-cell constants a = b = 182.38, c=60.87A, t~ ----/3 ----90, oV= 120 °. The crystals diffract beyond 2.4 and 2.5 A resolution, respectively, using a rotating anode as an X-ray source.

Improved procedure for separation and purification of Arthronema africanum phycobiliproteins

“…2, lane 2). Their molecular masses of 17 and 19 kDa, respectively are lower than those reported for other cyanobacteria (Moreno et al 1997;Minkova et al 2003;Patel et al 2005).…”

“…The molecular masses of a (16 kDa) and b (18 kDa) subunits of A. africanum APC (Fig. 2, lane 3) are lower than those of other cyanobacteria (Moreno et al 1997;Zolla et al 2002). Also, a few additional bands of some crude extract impurities other than C-PC were observed.…”

“…Recently we have described a non-chromatographic, rivanol-sulfate method for purification of C-PC from Spirulina (Arthrospira) fusiformis (Minkova et al 2003) as an attractive alternative to the procedures for purification of PBPs that usually combine fractional ammonium sulfate precipitation and various chromatographic methods (Moreno et al 1997;Zolla et al 2002;Patel et al 2005).…”

Large‐scale isolation and purification of C‐phycocyanin from the cyanobacteria Anabaena marina using expanded bed adsorption chromatography

“…Recently, this protein was reported to induce apoptosis in some carcinoma cells12 and human chronic myeloid leukemia cells 13. Preliminary X‐ray diffraction studies of C‐PC from S. platensis, F. diplosiphon and A. quadruplicatum determined the protein dimensions in different aggregation states, indicating an equivalent radius for the trimeric state of C‐PC of 43.2 Å 14, 15…”

Methods for Extraction, Isolation and Purification of C-phycocyanin: 50 years of research in review

“…(Swanson & Glazer, [18] ) Nevertheless, other compounds apart from the phycobilisome were present in the final products due to the sample pre-treatments needed to perform HPLC. In order to optimize phycobiliprotein isolation, the chromatographic method was modified by adapting resins used in the solid phase, varying the polarity and pH of the eluent solution (Moreno et al, [19] ), and using magnesium chloride precipitation with further diffusion in polyethylene glycol gel. By enhancing overall specificity, the isolation of pure C-phycocyanin and allophycocyanin was obtained, but the yielding mass was significantly decreased.…”