The absorbance at 620 and 280 nm correspond to PC and total
protein, respectively. PC is considered food grade when A 620 /A 280
absorbance ratio is greater than 0.7, absorbance ratio 0.7 to 3.9 and
above 4 have been considered as reagent and analytical grade,
respectively [16].
4 Notes
1. All buffers should be prepared using deionized water and analytical grade reagents.
2. Generally, the color of the crude extract will depend on the type
of the buffer used. Water and Na-phosphate buffer produces
green-colored crude extracts, whereas CaCl 2 solution (1.5%)
produces blue-colored crude extract (Fig. 2).
3. The crude C-PC purity and yield will depends on the type of
buffer and cell disruption method used for the phycocyanin
extraction. In our previous study, 12 h incubation of biomass
with the CaCl 2 solution on rotary shaker gave food-grade
purity, whereas using Na-phosphate buffer and sonication did
not give food-grade purity [17].
4. If the ammonium sulfate contains lumps, then these should be
broken up before adding.
5. Determine the volume of saturated ammonium sulfate solution
necessary to give the desired percentage of saturation using
web page (ammonıum sulfate calculator http://www.pro
teinchemist.com/cgi-bin/s2.pl).
6. Dialysis should be performed with large external volumes and
adequate stirring, as well as frequent exchanges of the buffer.
Fig. 2 Crude extract of phycocyanin obtained with Na-phosphate buffer (green
color) and CaCl 2 solution (blue color)
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Mahammed Ilyas Khazi et al.