Proteins interfacial property

The fluorescence lifetime is sensitive to the environment of the fluorophore, and in membranes this usually means the surrounding fatty acyl chains or the membrane protein interfacial region (see summary in Table 5.3). Generally, the lifetime of membrane-bound fluorophores is rather less sensitive to the types of subtle alterations which are encountered in membranes as compared to the fluorescence anisotropy parameters. The gel-to-liquid crystalline phase transition is a notable exception where most fluorophores show an alteration in lifetime properties. Although, again, the anisotropy (see below) is the most sensitive parameter in this regard, the fluorescence lifetime has been used with considerable success in the study of phase transitions and lateral phase separations. Fluorophores used to yield information on the... 

Rouimi, S., Schorsch, C., Valentini, C., Vaslin, S. (2005). Foam stability and interfacial properties of milk protein-surfactant systems. Food Hydrocolloids, 19, 467 178. 

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-... 

Surface properties of proteins in general, 296-298 (table) purification methods based on, 272 Surface tension and interfacial properties, 609-628. see also Interfaces Surfactants, see also Interfacial tension definition and adsorption kinetics of, 617-618, 639... 

Aqueous pH alters the protein charge property and affects the extraction efficiency. Haemoglobin (Mw 64,500, pi 6.8) is a difficult protein in terms of being able to completely extract it into reverse micelles. The representative anionic surfactant, di-2-ethylhexyl sulfosuccinate (AOT), cannot extract it, and gives rise to an interfacial precipitate. In contrast, we succeeded in the complete extraction of haemoglobin using synthetic anionic surfactants, dioleyl phosphoric acid (DOLPA), as seen in... 

LTI pyrolytic carbon is one of the very few synthetic materials generally accepted as suitable for long-term blood contact applications (1 ). Although a number of hypotheses have been formulated with respect to the blood tolerability of materials, a general theory or mechanism is not yet available. Nyilas, et al., ( ) have shown that in certain situations the local hemodynamics can play a predominant role, while in most cases the solid-blood interfacial properties have been shown to be equally important (2, 3). It is assumed that understanding the plasma protein adsorption processes on solids used for blood-contact applications will lead to a better understanding of solid-blood interactions (, 2, ... 

Protein interfacial layers also control traditional surface physicochemical properties of friction, wear, and lubrication in the joints of articulated bones—e.g., in hip joints. Little is known about the rubbing surfaces and the filling fiuids of the natural ball and socket connections except that they are predominately cartilaginous, glycoprotein, and proteoglycan materials. 

Wilkie summarized the important interfacial properties of gelatin (7), and Stenzel and co-workers prepared a similar review of the features of collagen which underlie that protein s fundamental importance as a biomaterial (8, 9). 

The complexity and diversity of structures in the native proteins eluded any attempt to produce some simple conformation that accounted for their interfacial properties. The study of synthetic polypeptides with non-polar side chains has provided good evidence to support the view that the a-helix can be stable at the air-water interface (5), and it is therefore possible that the interfacial denaturation of proteins is mainly a loss of the tertiary structure (6, 7, 8). Since for a typical protein an a-helix takes up about the same area per residue as the p conformation, it can be accommodated as easily. Moreover, like the p conformation but unlike a more randomly coiled structure, it is linear and therefore compatible with a plane surface without loss of configurational entropy (5). In this respect a plane surface may favor an ordered over a more random structure. The loss of solubility of the spread protein can then be attributed to intermolecular association between hydrophobic side chains exposed as a result of the action of the interface on the polar exterior of the molecules. 

Direct, unmediated electrochemistry of redox enzymes has interested many researchers in several aspects. Understanding of the thermodynamics, kinetics, stoichiometry, and interfacial properties of redox enzymes is obviously important. The most attractive aspect, however, is the use of enzyme electrodes as novel electrochemical biosensors and their applications to bioreactors and biofuel cells. Although the observation of direct electrochemistry of small redox proteins has become almost commonplace as the consequence of extensive research over the past decade, the corresponding study with larger redox enzymes has proved more elusive. The difficulty lies mainly in that the redox centers are located sufficiently far from the outermost... 

Monolayer techniques were used to characterize the interfacial properties of the resultant Fractions. Fraction I contained highly cohesive complexes that did not unfold at the interface and had an average diameter of 9.1 nm. These particles are thought to represent submicelles, previously identified in micelle formation. Fraction II showed interfacial properties that are characteristic of spread casein monomers, and contained mainly a -casein. The results are discussed in relation to casein interactions and micellar formation. Mixed monolayers of sodium caseinate/glyceride monostearate (NaCas/GMS) were also examined at different composition ratios. The results show that for low surface pressures (0-20 mNm ), there is a condensation ascribable to hydrophobic interactions in the mixed film. At high surface pressures, the hydrophobic interaction is modified and the protein is expelled from the monolayer into the subphase. These results are discussed in relation to emulsion stability. 

PAQUIN ET AL. Interfacial Properties of Milk Casein Proteins... 

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