Study on the interaction of protein with Sulfonazo III by Rayleigh light scattering technique and its application Original Research Article

This is the first report on the determination of proteins with Sulfonazo III by Rayleigh light scattering (RLS). At pH 4.23, the weak RLS of Sulfonazo III can be enhanced greatly by the addition of proteins, resulting in three characteristic peaks. Based on this, the reaction of Sulfonazo III and proteins was studied and a new method for quantation of proteins has been developed. This method is very sensitive (0.30–30.5 μg ml–1 for bovine serum albumen), rapid (<2 min), simple (one step), tolerance of most interfering substances, and gives a close value to that of Coomassie Brilliant Blue method in the determination of proteins in human serum. Mechanistic studies show that the RLS peaks correspond to the absorption valleys of the protein-Sulfonazo III complex.