The value of numerical modeling of aquifers in data-poor regions

Abstract

The adsorption and desorption of plasma proteins—albumin, γ-globulin, and fibrinogen—on copolypeptide and silicone surfaces have been studied. The process is characterized by three stages; an initial brief period where adsorption is reversible; a second phase where the adsorbed proteins undergo a slow conformation change based on the period of adsorption and where protein is essentially irreversibly adsorbed; in the final stage, denatured material is slowly desorbed. In the second stage the process is essentially irreversible, desorption being very slow; the third stage is essentially irreversible, adsorption of denatured material being improbable. The adsorption process may be represented by a two-state Oreskes/Singer plot, there being an apparent surface phase change at 50–60% surface coverage. Albumin and fibrinogen molecules are adsorbed side-on; γ-globulin is adsorbed in an end-on configuration. Surface denaturation seems to be driven by a need to increase hydrophobic bonding with the surface and adsorption is heavily entropic in nature. In the desorbed material, albumin and fibrinogen sustain a marked decrease in α-helical content; γ-globulin loses most of its β-sheet structure.