The method uses the CEM Sprint Protein Analyzer (CEM Corp.,
Matthews, NC, USA; www.cem.com). The method is based on
protein-tagging technology where the sample is mechanically
mixed with an anionic dye that binds to cationic groups of the basic
amino acid residues (histidine, arginine, and lysine) and to free
amino terminal groups. The amount of unbound dye remaining in
solution after the insoluble protein has been removed by filtration
is determined by measuring its absorbance. The amount of protein
present in the original solution is proportional to the amount of dye
removed from the solution. The method is calibrated