5. Slowly add a pre-weighed quantity of ammonium sulfate to
reach a saturation of 70%, and stir the mixture for nearly 6 h.
6. Transfer the ammonium sulfate precipitated solution to conical
centrifuge tubes and centrifuge at 6,000 Â g for 15 min 4
C.
7. Remove the supernatant carefully, and add a few milliliters of
Na-phosphate buffer to the pellet to resuspend the
phycocyanin.
8. Transfer the phycocyanin solution to dialysis tubing cellulose
membrane using a Pasteur pipette and dialyze overnight
against 2 L Na-phosphate buffer (see Note 6).
9. Decant phycocyanin solution into centrifuge tubes and centrifuge at 6,000 Â g for 10 min to remove any undissolved
material.
Fig. 1 The scheme of the overall purification process: (a) biomass suspended in Na-phosphate buffer, (b)
crude PC extracts obtained with Na-phosphate buffer (green) and CaCl 2 (blue), (c, d) ammonium sulfate
precipitates, (e) dialysis, (f) gel filtration chromatography, (g) ion-exchange chromatography, (h) purified C-PC
fractions, (i) lyophilized C-PC
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Mahammed Ilyas Khazi et al.