Surfactant interactions, protein

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

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... 

In the case of the rather porous and flexible structure of sodium caseinate nanoparticles, the data show that the interaction with surfactants causes a tendency towards the shrinkage of the aggregates, most likely due to the enhanced cross-linking in their interior as a result of the protein-surfactant interaction. This appears most pronounced for the case of the anionic surfactants (CITREM and SSL) interacting with the sodium caseinate nanoparticles. Consistent with this same line of interpretation, a surfactant-induced contraction of gelatin molecules of almost 30% has been demonstrated as a result of interaction with the anionic surfactant a-olefin sulfonate (Abed and Bohidar, 2004). 

Figure 6.8 Sketch of proposed molecular mechanism of protein-surfactant interaction for CITREM + sodium caseinate (0.5 % w/v in aqueous medium (pH = 7.2, ionic strength = 0.05 M) at 293 K. Picture (I) shows the water molecules bound with polar groups of the protein and surfactant, as w ell as w ater molecules structured as a result of hydrophobic hydration around the hydrocarbon chain of the surfactant. (For clarity, the free w ater molecules are not shown.) Picture (H) demonstrates the release of bound and structured water molecules resulting Rom the predominantly hydrophobic interactions between protein and surfactant. Reproduced Rom Semenova et al. (2006) 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. 

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). 

Lips, A., Ananthapadmanabhan, K., Vethamuthu, M., Hua, X., Huang, L., Yang, L., and Vincent, C., On skin protein-surfactant interactions, Preprint of the Society of Cosmetic Chemists Annual Scientific Seminar, Washington DC, p. 25, March 2003. 

Although a few general guidelines exist, the design of such mentioned extraction schemes is still a trial-and-error proposition. Consequently, more basic information on the nature of the lipid -protein - surfactant interactions is still required. It should also be noted that in most instances, the micellar "extraction" step is merely the prelude to further fractionation (usually by electrophoretic, column or hydrophobic chromatographic techniques) and purification of the desired biological components (402-404). 

To obtain the high extraction efficiency of a target protein, we need to design reverse micelles having sufficient hydrophobicity to extract the protein and prepare the conditions for enhancing the protein-surfactant interaction to form a protein-surfactant complex, which is a crucial intermediate for reverse micellar protein extraction. 

On the protein extraction behaviour using reverse micelles, the protein-surfactant interaction between charged protein surfaces and surfactant headgroups is a dominant factor in distinguishing the target proteins. In particular, some researchers have suggested that a protein can be extracted as a hydrophobic ion complex between a protein and surfactant molecules [6,7,12-15]. Therefore, an intrinsic factor of proteins also gives considerable modulation in the extraction behaviour, in which the environmental factors were maintained. 

Hermeling S, Jiskoot W, Crommelin DJA, et al. Reaction to the paper interaction of polysorbate with erythropoietin a case study in protein-surfactant interactions. Pharm Res 2006 23(3) 641-642. 

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. 

Ananthapadmanabhan K. P. Protein-surfactant interaction. In Goddard E. D., Anathapadmanabhan K. P., eds. Interaction of Surfactants with Polymers and Proteins. Boca Raton, FL CRC Press, 1993 318-366. 

The early work on the interactions of synthetic surfactants and fatty acid anions with proteins was reviewed by Putnam [9] in 1948 and the following 20 years by Steinhardt and Reynolds [10]. The expansion of the field has led more recently to reviews and monograph chapters dealing with specific areas of protein-surfactant interactions, such as the solubilization of membranes by detergents [11] and the use of surfactants in membrane solubilization and reconstitution of membrane proteins [12], as well as more general reviews [13,14,15],... 

V. EXPERIMENTAL TECHNIQUES USED IN THE STUDY OF PROTEIN-SURFACTANT INTERACTION... 

The range of experimental techniques that have been used in the study of protein-surfactant interactions is summarized in Table 1. The most important questions to be answered are (a) the extent of... 

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