Albumin surface, behavior

The effective surface viscosity is best found by experiment with the system in question, followed by back calculation through Eq. (22-55). From the precursors to Eq. (22-55), such experiments have yielded values of [L, on the order of (dyn-s)/cm for common surfactants in water at room temperature, which agrees with independent measurements [Lemhch, Chem. Eng. ScL, 23, 932 (1968) and Shih and Lem-lich. Am. Inst. Chem. Eng. J., 13, 751 (1967)]. However, the expected high [L, for aqueous solutions of such sldn-forming substances as saponin and albumin was not attained, perhaps because of their non-newtonian surface behavior [Shih and Lemhch, Ind. Eng. Chem. Fun-dam., 10, 254 (1971) andjashnani and Lemlich, y. Colloid Inteiface ScL, 46, 13(1974)]. 

TiTany authors (I, 2, 3) have compared the surface behavior of macro- molecules, especially proteins, with the behavior of low molecular weight monolayers. This paper notes a series of effects that occurred when bovine serum albumin (BSA) was spread on various clean liquid surfaces and was compressed or decompressed. The transfer of the protein monolayer and of some small chain monolayers was also studied using a surface distillation technique. 

Using this method, we constructed a number of dynamic adsorption isotherms for several proteins on different surfaces. Here we present information for two proteins. The adsorption isotherm for bovine serum albumin (BSA) (87% monomer, 13% dimer described by the supplier as 100% monomer) is shown in Figure 6. A plateau concentration for BSA on an amine/ silane surface was 3.5 mg/m2, which is comparable with monolayer adsorption reported previously in a static system (3). [The effect of flow rate, ionic strength, and temperature is reported elsewhere (18).] Perhaps more interesting are the data for plasma fibronectin (produced and purified extensively in our laboratory), because adsorption characteristics of this protein have not been reported elsewhere. Since it is a protein intimately involved in cellular adhesion, its surface behavior is particularly relevant to implant biocompatibility. We found a plateau uptake of approximately 7.0 mg/m2 on both amine and dimethyldimethoxymethylsilane, and based on the assumption of monolayer coverage and a published axial ratio (20), we calculated that the molecule has dimensions of approximately 130 X 80 X 100 A. 

Fig. 6. A highly idealized model for the plasma albumin molecule to account for the N-F transformation and its relationship to the titration anomaly, the cooperative detergent binding, and the altered solubility behavior of the low pH form. The model contains four folded amphipathic subunits, the hydrophobic surfaces being buried in the N form and exposed in the F form. Holes around the periphery of the molecule represent the 10 to 12 strong binding sites for detergent ions which are destroyed, upon isomerization, with the exposure of a large number of weaker sites. Reprinted with permission from Foster (1960). Copyright by Academic Press, Inc.

Any detectable effect on the reaction or behavior of a particular system by the interior wall of the container or reaction vessel. Because proteins can form high-affinity complexes with glass and plastic surfaces, one must exercise caution in the choice of reaction kinetic conditions. Wall effects can be discerned if one determines catalytic activity under different conditions that minimize or maximize contact of the solution with the container. In principle, an enzyme-catalyzed reaction should proceed at the same rate if placed in a capillary or a culture tube however, contact with the wall is maximized in a capillary, and wall effects should be more prominent. Some investigators add bovine serum albumin to prevent adsorption of their enzyme onto the container s walls. 

From the experiments it is clear that poly electrolyte is adsorbed on the surface of the black lipid film. This applies both to the experiments with gelatin and bovine serum albumin, which gave no decrease of film resistance, and to the experiments with bovine erythrocyte ghost protein and polyphosphate. The adsorption of protein on the phospholipid-water interface may be controlled independently by investigating the electrophoretic behavior of emulsion droplets, stabilized by phospholipid, in a protein solution, as a function of pH. In this way Haydon (3) established protein adsorption on the phospholipid-water interface. If the high resistance (107 ohms per sq. cm.) of black lipid films is to be ascribed to the continuous layer of hydrocarbon chains in the interior of the film, as is generally done, an increase in film conductivity is not expected from adsorption without penetration. 

There are several recent examples of the switching of nonspecific protein binding on polymer surfaces by application of an external stimulus. Alexander and coworkers demonstrated that protein adhesion can be controlled on PNIPAM surface brushes [14, 181]. For instance, it was reported that the adsorption of FITC-labeled bovine serum albumin (FITC-BSA) on PNIPAM/hexadecanethiol micropatterned surfaces could be tuned by LCST. However, this effect was found to be less pronounced after prolonged incubation times or repeated heating/cooling cycles. The authors suggested that this behavior could be due to unspecific PNIPAM-protein interactions [14],... 

Wertz CF, Santore MM (1999) Adsorption and relaxation kinetics of albumin and fibrinogen on hydrophobic surfaces single-species and competitive behavior. Langmuir 15(26) 8884-8894... 

The Behavior of Albumin in Plasma at the Oxidized Silicon Surface. A chance for albumin to be adsorbed out of plasma, not yet encountered on any of the materials tested, could be provided by removing fibrinogen and some globulins from competition. Some normal intact plasma was... 

No surface was found on which plasma would deposit albumin preferentially, even though albumin is its most abundant component. The present study of heated plasma to which fibrinogen had then been added and of the behavior of albumin in presence of another protein suggests that in normal plasma there is something more than the sum of competing proteins that keeps albumin from being adsorbed. 

Adsorption at the aqueous-air interface from binary solutions of proteins and surfactants can be conveniently followed by surface tension measurements in which the protein concentration is kept constant and the surfactant concentration is increased to concentrations in excess of the cmc. Studies of this type were first carried out not with proteins but with polyethylene oxide in the presence of SDS [70], and it was found that plots of surface tension as a function of surfactant concentration showed a number of interesting features in comparison with the surface tension concentration plot in the absence of polymer (Fig. 4). Very similar behavior to that first observed for the polyethylene oxide-SDS system has been found for protein-surfactant systems including bovine serum albumin plus SDS [67], gelatin plus SDS [52], and reduced lysozyme plus hexa (oxyethylene) dodecyl... 

---