Protein—ligand interactions studied on bovine serum albumin with free and polymer-bound Cibacron Blue F3G-A as ligand with reference to affinity partitioning

Abstract

The interactions in aqueous solutions between bovine serum albumin and the textile dye Cibacron Blue F3G-A, in both the free and polymer-bound forms, were studied using difference spectroscopy and gel chromatography. The polymers used as dye carriers were dextran, Ficoll, hydroxypropyl-starch, poly(vinyl alcohol) and poly(ethylene glycol). The addition of poly(ethylene glycol) to the solutions decreases the number of apparent binding sites on the albumin molecule, whereas this does not occur in the presence of dextran. The results were compared with the influence of polymer-bound dye on the partitioning of albumin in aqueous two-phase systems composed of dextran and poly(ethylene glycol). The partitioning of lactate dehydrogenase, which also interacts with this dye, was studied for comparison.