Displacement of protein

A.R. Mackie, P. Gunning, P. Wilde, and V. Morris Orogenic Displacement of Protein from the OilAVater Interface. Langmuir 16, 2242 (2000). 

Hunt, J.A., Dickinson, E., Horne, D.S. (1993). Competitive displacement of proteins in oil-in-water emulsions containing calcium ions. Colloids and Surfaces A Physicochemical and Engineering Aspects, 71,197-203. 

Mackie, A.R., Gunning A.P., Wilde, P.J., Morris, V.J. (1999b). The orogenic displacement of protein from the air-water interface by surfactant. Journal of Colloid and Interface Science, 210, 157-166. 

Displacement of the protein from the adsorbed layer in o/w thin films shows very different behavior from its a/w counterpart. Although displacement of protein from the o/w interfaces initiates at approximately the same solution composition (i.e., R = 0.1), there is little evidence for the stepwise displacement observed in the a/w thin films. This observation is further confirmation of the monolayer versus multilayer structure at the o/w and a/w thin films. The displacement of /3-lg has also been investigated in oil-in-water emulsions of n-tetradecane [46,47], In these reports it was shown that the protein was not completely displaced until R = 10, which was considerably higher than R = 1 - 2 in Figure 22. This will be discussed further below. 

It is difficult to establish a relation between valproate encephalopathy and increased serum ammonium concentrations. Valproate-induced hyperammonemic encephalopathy has been reported in several single case reports, but still it is difficult to ascertain whether hyperammonemia or valproic acid is the cause of the encephalopathy. In one case valproate was used in combination with lithium, which in itself could have caused encephalopathy by displacement of protein binding or other mechanisms, regardless of hyperammonemia (1181). In a second case it was also impossible to evaluate the effect of hyperammonemia on the level of consciousness, since it involved a woman who took valproic acid (30 g) in addition to... 

Surface dilatational rheology is a very sensitive technique to analyze the competitive adsorption/displacement of protein and LMWE emulsifier at the air-water interface (Patino et al., 2003). A common trend is that the surface dilatational modulus increases as the monolayer is compressed and is a maximum at the highest surface pressures, at the collapse point of the mixed film, and as the content of LMWE in the mixture increases. At higher TT, the collapsed protein residues displaced from the interface by LMWE molecules have important influence on the dilatational characteristics of the mixed films. The mechanical properties of the mixed films also demonstrate that, even at the highest tt, the LMWE is unable to displace completely protein molecules from the air-water interface. 

Three-stage "orogenic" mechanism for displacement of proteins by water-insoluble LMWE spread at the air-water interface. 

The simplest mixed interface consists of a protein and a small molecule, such as a surfactant or lipid. We will model competitive displacement of proteins... 

The displacement of proteins at the oil-water interface is important in terms of the storage stability of protein-stabilized emulsions. Food emulsions requiring longterm stability need interfaces that could resist displacement to prevent coalescence during storage. 

The addition of an emulsifier before emulsification may alter the nature of surface interactions. For example, a-la could be adsorbed at an interface threefolds higher than P-lg when Tween 20, the water-soluble emulsifier, was added before homogenization (Courthaudon et al., 1991a). Courthaudon et al. (1991a,b,c) showed that the addition of Tween 20 immediately after emulsion formation led to a complete displacement of proteins from the interface at an emulsifieriprotein molar ratio of 17 1. The presence of glycerol monostearate, the oil-soluble emulsifier, dissolved in the oil phase enhanced the displacement of proteins from the interface by Tween 20 (Dickinson and Tanai, 1992). It was also reported that the protein surface concentration in the fresh emulsion and the amount of water-soluble emulsifier required for complete displacement could be reduced by the oil-soluble anulsifier previously dissolved in the oil phase. 

Dickinson, E. and Tanai, S. 1992. Temperature dependence of the competitive displacement of protein from the emulsion droplet surface by surfactant. Food Hydrocolloids 6 163-171. 

Phenylbutazone and related (sulfapyridine) drugs.The activity of these drugs on platelet action is synergistic with the actions of warfarin. In addition, these drugs increase the pharmacologic effects of warfarin by displacement of protein binding. 

A number of other reports describe very significant reductions in endogenous markers of thyroid function in subjects and patients taking phenytoin or carbamazepine, " but not sodium valproate. However, there seems to be only two cases in which reversible hypothyroidism was seen, one with carbamazepine and phenytoin, and the other with carbamazepine alone. There is also a report of an arrhythmia in a patient with hypothyroidism and rheumatic heart disease given phenytoin this was attributed to the displacement of protein bound levothyroxine by phenytoin leading to an increase in free levothyroxine in the plasma. This report was later criticised by others, who suggested that the arrhythmia, if indeed there was one, was caused directly by the cardiac actions of... 

It is known that interfacial rheology of protein-surfactant mixed layers depends on the protein (random or globular), the surfactant (water-soluble or oil-soluble surfactant, ionic or non-ionic), the interface (air-water or oil-water), the interfacial (protein/surfactant ratio) and bulk (i.e., pH, ionic strength, etc.) compositions, the method of formation of the interfacial layer (by spreading or adsorption, either sequentially or simultaneously), the interactions (hydrophobic and/or electrostatic), and the displacement of protein by surfactant [7],... 

Refractometry Based on change in refractive index by the displacement of proteins... 

Figure 4 Displacement of protein caiibration curve in the presence of 0.1% SDS in the mobiie phase. Column SynChropak GPC 100, 250 x 4.6 mm D. Flow rate 0.5mL/min. Standard proteins.

Antia FD, Fellegvari I, Horvath C. Displacement of proteins in hydrophobic Interaction chromatography. Ind Eng Chem Res 1995 34 2796-804. 

---