Abstract
Interaction of Ponceau 3R with bovine serum albumin was studied by spectrophoto-metric, equilibrium dialysis and gel filtration method. In the presence of bovine serum albumin, absorption spectrum of Ponceau 3R shifted to higher wavelength from 503 mμ to 515 mμ with lowering optical density. The results of equilibrium dialysis and gel filtration showed that binding of Ponceau 3R to bovine serum albumin is essentially based on the Langmuir-type equation. Number of binding sites of bovine serum albumin to Ponceau 3R was approximately 5 over the pH range of 6 and 9, although it increased abruptly in further acidic region. Equilibrium constant of this reaction system was approximately 105M-1 in neutral and alkaline region, whereas it increased in acidic region.
