Protein interfacial

Pommier Y, Cherfils J (2005) Interfacial protein inhibition a nature s paradigm for drug discovery. Trends Pharmacol Sci 28 136 4-5... 

These assumptions were confirmed by the electrophoresis study of the washed creams. Electrophoresis of purified fat globules is a convenient method to characterize and quantify proteins adsorbed at the oil-water interface [35]. Electrophoretic data indicate that no casein, nor whey proteins, were adsorbed at the surface of raw-milk fat globule. Upon homogenization, caseins adsorbed preferentially at the lipid-water interface. In this case, bound a-lactalbumin accounted for 16% of the total interfacial proteins. Heat treatment also induced the interaction of proteins with the fat globules. The amount of bound proteins (per mg of lipids) for heated raw milk was half that for homogenized milk. 

A situation that commonly occurs with food foams and emulsions is that there is a mixture of protein and low-molecular-weight surfactant available for adsorption at the interface. The composition and structure of the developing adsorbed layer are therefore strongly influenced by dynamic aspects of the competitive adsorption between protein and surfactant. This competitive adsorption in turn is influenced by the nature of the interfacial protein-protein and protein-surfactant interactions. At the most basic level, what drives this competition is that the surfactant-surface interaction is stronger than the interaction of the surface with the protein (or protein-surfactant complex) (Dickinson, 1998 Goff, 1997 Rodriguez Patino et al., 2007 Miller et al., 2008 Kotsmar et al., 2009). 

Protein-polysaccharide complexation affects the surface viscoelastic properties of the protein interfacial layer. Surface shear rheology is especially sensitive to the strength of the interfacial protein-polysaccharide interactions. Experimental data on BSA+ dextran sulfate (Dickinson and Galazka, 1992), asi-casein + high-methoxy pectin (Dickinson et al., 1998), p-lactoglobulin + low-methoxy pectin (Ganzevles et al., 2006), and p-lactoglobulin + acacia gum (Schmitt et al., 2005) have all demon-... 

These requirements would be fulfilled if SDS were bound to the BSA monolayer in the form of small aggregates or pseudo-micelles. Such aggregates have been demonstrated to be formed as the result of the interaction of SDS and BSA in solution (2). Further, the electrostatic nature of the interaction was demonstrated by the fact that the complex was completely dissociated by adjusting pH to values above 10.0. Therefore, it is suggested that the cause of the marked shift in pK of the ammonium groups of the SDS-BSA surface complex was the presence of aggregates of SDS bound at cationic sites of the protein monolayer. It may be inferred from this hypothesis that the natural result of the interaction of anionic lipids with an interfacial protein film is the formation of a mosaic structure—one of the proposed characteristics of biological membranes. 

The time scale of fat crystallization is much shorter for topping powders than for ice cream mix as presented in Figure 2. This is due to the much higher emulsifier content in topping powder. The induction of fat crystallization in whippable emulsion systems is due to interfacial protein desorption from the fat globules of the emulsion mediated by the emulsifiers. This phenomenon is described in section 3.1. 

Water absorption into the fat phase of the topping results in interfacial protein... 

During ageing of the mix, interfacial milk protein hydration also increases simultaneously with protein desorption from the fat globules. The water content of the isolated cream layers after centrifugation of ice cream mix can be analyzed by Karl Fischer titration. From such analyses, interfacial protein hydration can be calculated (Figure 13). 

The voluminosity or hydration of interfacially bound protein may be calculated from the amount of water bound per gram of fat divided by the amount of protein bound per gram of fat. This corresponds to the volume of water per gram interfacial protein. Calculations show that emulsifiers facilitate interfacial protein hydration. This property is probably connected with their ability to desorb protein from the interface (Figure 14). 

Kang SA, Hoke KR, Crane BR. Solvent Isotope Effects on Interfacial Protein Electron Transfer in Crystals and Electrode Films. J. Am. Chem. Soc. 2006 128 2346-2355. 

Some of the areas where interfacial protein layers dominate the boundary chemistry are reviewed, and we introduce some nondestructive armlytical methods which can be used simultaneously and/or sequentially to detect and characterize the microscopic amounts of matter at protein or other substrates which spontaneously acquire protein conditioning films. Examples include collagen and gelatin, synthetic polypeptides, nylons, and the biomedically important surfaces of vessel grafts, skin, tissue, and blood. The importance of prerequisite adsorbed films of proteins during thrombus formation, cell adhesion, use of intrauterine contraceptives, development of dental adhesives, and prevention of maritime fouling is discussed. Specifics of protein adsorption at solid/liquid and gas/liquid interfaces are compared. 

An understanding of interfacial protein chemistry requires evaluation of the thermodynamics of the system under investigation as well as the energetic barriers responsible for the observed kinetics and affinity. Due to the kinetic methodology available for the antifluorescein system, the energetic barriers for complex decomposition... 

Lee, S.-H., Lefevre, T., Subirade, M., and Paquin, P. (2009). Effects of ultra-high pressure homogenization on the properties and structure of interfacial protein layer in whey protein-stabilized emulsion. Food Chem. 113,191-195. 

Sadana A. Interfacial protein adsorption and inactivation. Bioseparation 1993 3(5) 297-320. 

Gunning, A.R, Mackie, A.R., Kirby, A.R., and Morris, V.J. Scanning near-field optical microscopy of phase separated regions in a mixed interfacial protein (BSA) surfactant (Tween 20) film, Langmuir, 17, 2013, 2001. 

Jones, D.B. and Middelberg, A.P.J. Micromechanical testing of interfacial protein networks demonstrates ensemble behavior characteristic of a nanostructured biomaterial, Langmuir, 18, 5585, 2002. 

The sensitivity of cellular interactions to interfacial proteins probably is due to the presence of cell surface receptors for specific proteins and to the enhancement of receptor-protein interaction by the concentration of proteins at interfaces. To illustrate the role of specific proteins at interfaces,... 

Interfacial protein fluorescence is an in situ method that can provide real time data with a resolution of 0.1 s. This technique is a major advantage in that the protein adsorption-desorption dynamics may be determined without resorting to sample manipulation prior to analysis. Figure 9 illustrates adsorption-desorption dynamics for both BSA and 7-globulin at bulk equimolar concentrations of 6.671xM/L. The 7-globulin required 40 min to reach... 

The stabilizing properties of individual caseins, sodium caseinate and casein micelles are described with respect to the formation and behavior of emulsions. In particular, attempts are made to relate the properties of the emulsions (or rather the interfacial proteins) to the properties of the proteins and protein coitplexes dien they are in their solution or suspended state. In this, the stabilizing action of K-casein in the different emulsions is described an inpDrtant factor being its susceptibility to atack by rennet, which may serve as an indicator of its conformation on the interface. 

R451 L. J. C. Jeuken, Conformational Reorganisation in Interfacial Protein Electron Transfer , Biochim. Biophys. Acta, 2003,1604, 67... 

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