Proteins, surfactant effects

E. Dickinson and I. Chen Viscoelastic Properties of Protein-Stabilized Emulsions Effect of Protein-Surfactant Interactions. I. Agric. Food Chem. 46, 91 (1998). 

Stability of protein formulations investigation of surfactant effects by a novel EPR spectroscopic technique. Pharm Res, 1995. 12(1) 2-11. 

Where this factor plays a role, the hydrophobic interaction between the hydrocarbon chains of the surfactant and the non-polar parts of protein functional groups are predominant. An example of this effect is the marked endothermic character of the interactions between the anionic CITREM and sodium caseinate at pH = 7.2 (Semenova et al., 2006), and also between sodium dodecyl sulfate (SDS) and soy protein at pH values of 7.0 and 8.2 (Nakai et al., 1980). It is important here to note that, when the character of the protein-surfactant interactions is endothermic (/.< ., involving a positive contribution from the enthalpy to the change in the overall free energy of the system), the main thermodynamic driving force is considered to be an increase in the entropy of the system due to release into bulk solution of a great number of water molecules. This entropy... 

Figure 6.9 Effect of CITREM concentration on the molecular and thermodynamic parameters of complex protein-surfactant nanoparticles in aqueous medium (phosphate buffer, pH = 7.2, ionic strength = 0.05 M 20 °C) (a) extent of protein association, k = Mwcomplex/Mwprotem (b) structure-sensitive parameter, p (c) second virial coefficient, A2 (rnolal scale) (d) effective charge, ZE (net number n of moles of negative charges per mole of original sodium caseinate nanoparticles existing at pH = 7.2 (Mw = 4xl06 Da)). The indicated cmc value refers to the pure CITREM solution. Reproduced from Semenova et al. (2007) with permission.

Chen, J., Dickinson, E. (1998) Viscoelastic properties of protein-stabilized emulsions effect of protein-surfactant interactions. Journal of Agricultural and Food Chemistry, 46, 91-97. 

Ashton, P. et al. Surfactant effects in percutaneous absorption. 2. Effects of protein and lipid structure of the stratum comeum. International Journal of Pharmaceutics S7( l-3) 265-269, 1992. 

Surfactant Effects on Microbial Membranes and Proteins. Two major factors in the consideration of surfactant toxicity or inhibition of microbial processes are the disruption of cellular membranes b) interaction with lipid structural components and reaction of the surfactant with the enzymes and other proteins essential to the proper functioning of the bacterial cell (61). The basic structural unit of virtually all biological membranes is the phospholipid bilayer (62, 63). Phospholipids are amphiphilic and resemble the simpler nonbiological molecules of commercially available surfactants (i.e., they contain a strongly hydrophilic head group, whereas two hydrocarbon chains constitute their hydrophobic moieties). Phospholipid molecules form micellar double layers. Biological membranes also contain membrane-associated proteins that may be involved in transport mechanisms across cell membranes. 

Competitive Substrate Utilization. Various experiments with phenanthrene mineralization demonstrated partial inhibition with nonionic surfactants at doses less than that resulting in micellization. Such data suggest an alternative explanation for inhibition, other than surfactant effects on cell membranes and proteins. Possibly PAH-degrading microorganisms, or their competitors, utilize the surfactant as preferential substrate or carbon source. Jalvert et al. (66) made a similar conclusion about the effect of C12E4 on reductive dechlorination of hexachlorobenzene. 

In order to assess the effect of compression (expansion) on more complex mixed layers (protein + protein or protein + surfactant), we have simulated four different binary systems. The mixtures are composed of two species of the same spherical size in a 1 1 molar ratio. In all cases, one of the species (Type 1) interacts solely through the repulsive core potential both with particles of its same type and with particles of Type 2. The Type 2 particles, however, are able to form bonds with particles of their ovm type. The four different cases correspond to different classes of bonding between the particles of Type 2 (a) no bonds, (b) very-easy-to-break bonds (fcmax = 0-3)i (c) breakable bonds (fcmax = 0-5), and (d) permanent bonds (fcmax = °°)-The structures of fhe four differenf sysfems after 6 X 10 equilibration time steps are shown in Figure 23.3. Case (a) represents a perfect mixture since... 

Finally, we have shown that the stress response to compression of a mixed system (protein -I- protein or protein - - surfactant) is not significantly affected by the nature of the bonding mechanism of the bond-forming species. In contrast, the "competitive desorption" induced by compression favors the displacement of one or other of the species depending on the extent of breakability of the bonds. This phenomenon seems to arise as a consequence of the delicate balance between a "bond-enhanced adsorption effect" and a "drag-desorption mechanism."... 

U.S. 4306987 (1981) [122] Kaneko (BASF Wyandotte) Block polyoxyalkylene nonionic surfactant Effective foam control spot-free wash items effective against encrusted protein soils... 

Tn nature proteins interact with ions, lipids, and other proteins as part of the broad spectrum of necessary biological processes including membrane functionality and antigen-antibody effects. Protein functionality can be altered greatly by the interaction of proteins with surface-active agents, and the subject of protein-surfactant interaction is important in relation to food, cosmetic, and biomedical areas. 

The dissociation of protein-surfactant complexes can be induced by the presence of another surfactant with a lower hydrophobic-hydrophilic balance (higher cmc) due to the formation of mixed micelles [105], This effect is illustrated in Fig. 15 for complex formation between insulin and SDS in the presence of a constant concentration of sodium n-decylsulphate (SDeS). In a binary mixture of similar surfactants (SDS + SDeS) that behave as an ideal mixture in the micelles and in the solution, the cmc (C,2 ) is given by [106,107]... 

Most of the physicochemical investigations were carried out with surfactant foams. However, in biotechnology, protein foams in combination with surfactants play a role. The properties of these protein and protein/surfactant foams differ considerably from those of pure surfactant foams. Therefore, the results evaluated by surfactant foams can only be partially applied to protein foams. Since proteins adsorb at interfaces at very low concentrations, protein concentrations of as little as Imgl can influence foaming [2]. Protein concentration in industrial cultivation media are far above this limit, because of the high protein content of complex nutrient media and because the microorganisms produce proteins and excrete them into the cultivation medium. In this chapter model protein foams and protein/surfactant foams formed in cultivation media, and their effect on flotation of proteins and microorganisms, are discussed. The results with model protein foams are compared with those of cultivation foams. 

Loo, R.R., Dales, N., Andrews, RC. (1994) Surfactant effects on protein structure examined by electrospray ionization mass spectrometry. Protein Science, 3(11), 1975-1983. 

Stationary phase-macromolecule repulsion is yet more evident in SEC of proteins on SW columns in sodium dodecyl sulfate (SDS), in which solvent strongly anionic protein-surfactant complexes are formed. A pronounced ionic strength dependence was observed (76) for the MW calibration curves obtained with a series of globular proteins in 0.1% SDS containing 0.02 M - 0.2 M pH 7 phosphate buffer. The effect of ionic strength on the shapes of these calibration curves is quite similar to observations with strong polyanions. The pronounced influence of I on Ksec °f proteins in SDS eluant was also observed by Takagi et al. (77). 

Salt effects in protein/surfactant systems have been widely studied. As may be imagined, the effects can be quite complex and they vary considerably from system to system, with pH, with absolute ionic strength, and so on. For a system showing fairly simple behavior one may cite the combination of lysozyme and SDS described earlier see Figure 30 (131). For a brief review of the field, with references, the reader is referred to Ref. 129. 

Surfactant interactions with proteins have been extensively studied by cosmetic scientists, with special interest in the effects of tensides on skin and hair keratin. Despite the increasing availability of highly skin-compatible surfactants that still retain excellent detergent properties, the adverse reactions potentially caused by these ingredients have never been underestimated by dermatologists and cosmetic chemists, and the subject persists as one of the key topics of cosmetology. The physicochemical aspects of protein-surfactant interactions have been investigated with a more theoretical approach in noncosmetic contexts by many scientists who exhaustively explored the behavior of binary systems of anionic tensides and native proteins (55-59). 

The mechanisms and effects of protein-surfactant interactions reviewed here are important for understanding the specific action of proteins in detergency. 

Malcharek S, Hinz A, Hilterhaus L, Galla H-J (2005) Multilayer Structures in Lipid Monolayer Films Containing Surfactant Protein C Effects of Cholesterol and POPE. Biophys J 88 2638-2649... 

The material used for the electrode also had a strong influence on E° (Figure 7). For Mb in DDAB films, F° values ranged from -50 to +120 mV versus NHF at pH 5.5 in the order lTOapparent rate constant depended weakly on electrode material. Clearly, proteins in snrfactant films do not give the same F° -valnes as in solntion. The influence of surfactant type and electrode material suggests a possible electrical double-layer effect at the electrode-film interface on the potential felt by the protein. Surfactant-protein interactions may also be important. 

The red blood cells (RBC) test [12] also investigates the protein denaturing effect of surfactants by using a biological material as substrate, the red blood cells. 

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