2.4. Determination of Phycocyanin and Allophycocyanin
Protein extraction and determination: PB buffer is used to extract
phycocyanin and allophycocyanin after repeated freezing and thawing (Hu
et al., 2018). A spectrophotometer was used to determine the
concentration of phycocyanin and allophycocyanin (Bhalamurugan et al.,
2018). The relationship between protein concentration and absorbance is
Eqs (3) (4):
\(PC(mg/mL)=(A_{620}-0.474A_{652})\div 5.34\) (3)
\(APC(mg/mL)=(A_{652}-0.208A_{620})\div 5.09\) (4)
The determination of phycocyanin content comes from the formula (5):
\(PC\ content(mg/g)=PCV/M\) (5)
where V represents the volume of the PB solution of the extracted
protein, and M represents the dry weight of FACHB-314 at this
concentration.
According to Eqs (6), the phycocyanin and allophycocyanin in the algae
can be obtained in sequence:
\(\text{PC\ content}=(C1\times V1)(C2\times V2)\) (6)
Among them, PC content represents the content of phycocyanin per unit
cell dry weight (mg/g); C1 represents the concentration of two proteins
(mg/ml), V1 represents the volume of phosphate buffer (ml), and C2
represents FACHB-314 Corresponding dry cell weight (g/L); V2
represents the weighed volume of algal liquid (mL).
According to Eqs (7), the purity of phycocyanin can be obtained:
\(\text{PC\ production}=PC\ content\times DCW\) (7)
Among them, PC content represents the content of phycocyanin per unit
cell dry weight (mg/g); DCW represents the dry cell weight (g/L) of the
phycocyanin content.