Abstract
The binding of some azo colors with bovine plasma albumin was studied by equilibrium dialysis method. These azo colors studied include amaranth, newcoccine, orange I, orange II and orange G. The moles of bound color per protein mole and the free energies for the binding of these colors by bovine plasma albumin were determined at pH 5.2-8.9. The free energies for the binding of these colors are in the neighborhood of -5, 800 to -7, 200 cal/mole. Although the value of the binding capacity is very difficult to determine with a high degree of accuracy, these values of the binding capacity obtained in our experiments were from 2 to 50. These values depend on the kinds and the positions of substituents in azo colors.
