Surfactant/protein mixtures

The orientation and Frumkin adsorption models have recently been combined to describe adsorption layer for surfactant-protein mixtures in [37] and [38]. 

Perez-Gil, J., Cruz, A., and Casals, C. (1993). Biochim. Biophys. Act. 1168, 261-270. Solubility of hydrophobic surfactant proteins in organic solvent/water mixtures. Structural studies on SP-B and SP-C in aqueous organic solvents and lipids. 

The action of lipid-protein mixtures, mimicking those of physiological lung surfactants can be, and has been, studied in Langmuir troughs. For instance, in one of such studies the monolayers were subjected to compression-expansion cycles. At... 

FIG. 7.3 GPC elution curves for protein, surfactant, and mixtures of protein and surfactant. (From Miyazawa, K., Ogawa, M., and Mitsui, T., Int. J. Cosmet. Sci., 6, 33, 1984. Reproduced with permission.)... 

Let us now discuss mixtures of proteins with low-molecular weight surfactants. These mixtures are of great practical importance for the stabilisation of emulsions and foams, and play an important role in biological systems. Let us consider equilibrium ideal (with respect to the enthalpy) solutions of proteins and surfactants. If such a solution contains i different surfactants (or proteins) which exist in j different states at the interface, the following system of equations from (2.26) and (2.27) may be formulated [24,25] ... 

Interfacial rheology deals with the shear and dilatational mechanical behavior of adsorbed and deposited layers of surfactants, proteins, polymers, and other mixtures at fluid fluid interfaces and of monolayers at solid surfaces. The orientation of the adsorbed molecules,... 

An approach to reduce the deleterious effects of lignin is delignification of pre-treated UgnoceUulosic biomass. Another approach is the introduction of additives to hydrolysis mixtures, including surfactants, proteins and other lignin-binding polymers. In particular, poly (ethylene glycol) has been foxmd to be effective (32). 

As shown in Figure 1, after the focusing step, the gel strip is transferred to a small test tube and bathed in a 10 volume excess of interfacing solution, for up to 15 min, so as to begin to saturate the isoelectric proteins with the SDS anionic surfactant. Thiol agents (e.g., DTT, TBP) can be omitted if the protein mixture has been properly reduced and alkylated prior to the focusing step. The equilibrated strips are then individually transferred to the upper edge of a... 

The lung alveolar surfactant (AS) is a complex lipid-protein mixture, essential for the normal respiratory activity [1-4]. The main AS function in vivo is to reduce the alveolar surface tension (y, mN/m) and to provide alveolar stability [5,6], The absence of a mature AS in the lungs is the main reasmi for the development of neonatal respiratory distress syndrome (NRDS) that often has a lethal outcome [7]. 

Pulmonary surfactant protein B BiceUar Upid mixtures 104... 

Breathing is enabled by lung surfactant, a mixture of proteins and lipids that forms a surface-active layer and reduces surface tension at the air-water interface in lungs. Surfactant protein B (SP-B) is an essential component of lung surfactant. Researchers probed the mechanism underlying the important functional contributions made by the N-terminal 7-residues of SP-B, a region sometimes called the insertion sequence . These studies employed a construct of SP-B, SP-B (1-25,63-78), also called Super Mini-B, which is a 41-residue peptide with internal disulfide bonds comprising the N-terminal 7-residue insertion sequence and the N- and C-terminal helixes of SP-B. CD, solution NMR, and SS NMR were used to study the structure of SP-B (1-25,63-78) and its interactions with phospholipid bilayers. Comparison of results for SP-B (8-25,63-78) and SP-B (1-25,63-78) demonstrates that the presence of the 7-residue insertion sequence induces substantial disorder near the center of the lipid bilayer. ... 

Surfactant is a lipid-protein complex that is synthesized and released hy alveolar type II epithelial cells. This complex surface-active compound contains both hydrophobic and hydrophilic regions to allow the molecule to spontaneously adsorb to and form monolayers along the air-liquid interface. The role of surfactant in pulmonary fluid mechanics depends on its natural ability to disrupt intermolecular forces by interfering with the attractive forces between water molecules at the interfacial surface—thus lowering the surface tension. While this surfactant mixture is largely comprised of lipids (90%), the surfactant proteins (10%) are required for normal function (Hall et al. 1992 Yu and Possmayer 1993). Finally, the molecule dipalmitoyl phosphatidylcholine (DPPC) makes up 80% of the phospholipid and is largely responsible for the ultra-low surface tensions necessary for respiratory function (<5 dyn/cm) (Klaus et al. 1961 Hawco et al. 1981 Tchoreloff et al. 1991). 

Amirkhanian JD, Bruni R, Waring AJ, Taeusch HW. Inhibition of mixtures of surfactant lipids and synthetic sequences of surfactant proteins SP-B and SP-C. Biochim Biophys Acta 1991 1096 355-360. 

Normal lungs, however, produce a chemical substance referred to as pulmonary surfactant. Made by alveolar type II cells within the alveoli, surfactant is a complex mixture of proteins (10 to 15%) and phospholipids (85 to 90%), including dipalmitoyl phosphatidyl choline, the predominant constituent. By interspersing throughout the fluid lining the alveoli, surfactant disrupts the cohesive forces between the water molecules. As a result, pulmonary surfactant has three major functions ... 

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