Protein Purification and Characterization

After ammonium sulfate precipitation and desalting of proteins, the highest protein concentration of dialyzed samples was subjected to a column (diameter: 1.5 cm, length: 30 cm, Bio-Rad, Hercules, CA, USA) containing Sephadex G-75 as the stationary phase, and in another trial, the column contained Sephadex G-50. The column was eluted with citrate buffer, pH 5. The eluted solution was collected in Cuvette tubes as fractions, each of 1 mL in size. Each fraction was used to measure dissolved protein concentration at 280 nm, enzyme activity in U/mL, and specific activity in U/mg protein as previously described [35 ,36 (link)].