Dynamic adsorption and desorption of proteins

Abstract

To study the dynamics of adsorption and desorption of plasma proteins, bovine serum albumin(BSA), γ-globulin, fibrinogen, and plasma fibronectin(FN) were labeled with131 I and phosphate buffered solutions of the single proteins and of the mixed proteins were used for the in vitro adsorption and desorption study. When the proteins in single concentration were first adsorbed onto a polyethylene tube and desorbed after 60 min adsorption by changing the flowing liquid from the protein solution to a buffered saline without any protein, FN molecules were found to remain adsorbed so strongly on the tube surface that their desorption did not take place even after washing with the flowing buffer. On the contrary, BSA was rather readily desorbed from the tube surface upon continued washing. A similar result was obtained when the protein pre-adsorbed on a polyethylene film was exposed to the solution of the same but unlabeled protein; the adsorbed FN was not replaced, while the BSA solution expelled the adsorbed BSA molecules from the polyethylene surface. Adsorption and desorption behaviors of γ-globulin and fibrinogen were intermediate between those of BSA and FN. When a mixture of BSA and FN was allowed to flow into the polyethylene tube at a concentration of 0.05 mg ml−1 for each protein, BSA adsorption took place more rapidly and significantly than FN in the initial stage of adsorption but was decreased after passing a maximum, whereas FN was increasingly adsorbed onto the polyethylene surface with time and finally surpassed BSA in the adsorption amount.