Mixed micelle detergent

In Protocol IB, a soluble whole cell extract is produced by lysis in RIPA, a mixed micelle detergent-containing buffer. RIPA buffer results in extraction of proteins without complete denaturation and cellular antigens are maintained in conformations that can be detected by immrmopredpitation (Protocol 14B). How-... 

In Protocol 14C, immunoprecipitation is performed under disruptive conditions in a mixed micelle detergent buffer (RIPA). Most physiological interactions are dissociated imder these stringent conditions, and usually only the antigen protein and veiy tightly-associated proteins are recovered by immunoprecipitation. This method is useful to quantitate levels of pS]methionine labelled protein antigen, and to study synthesis and degradation rates by pulse chase analysis. 

In another study of the physical behavior of soap-LSDA blends, Weil and Linfield [35] showed that the mechanism of action of such mixtures is based on a close association between the two components. In deionized water this association is mixed micellar. Surface tension curves confirm the presence of mixed micelles in deionized water and show a combination of optimum surface active properties, such as low CMC, high surface concentration, and low surface concentration above the CMC. Solubilization of high Krafft point soap by an LSDA and of a difficulty soluble LSDA by soap are related results of this association. Analysis of dispersions of soap-LSDA mixtures in hard water shows that the dispersed particles are mixtures of soap and LSDA in the same proportion as they were originally added. These findings are inconsistent with the view that soap reacts separately with hard water ions and that the resulting lime soap is suspended by surface adsorption of LSDA. The suspended particles are responsible for surface-active properties and detergency and do not permit deposits on washed fabric unlike those found after washing with soap alone. 

A. (1986a). Preparation of liposomes via detergent removal from mixed micelles by dilution. The effect of bilayer composition and process parameters on liposome characteristics, Pharm. Weekbl. 

Figure 3. Apparent aggregation number (N j) of mixed micelles containing detergent and/or C21-DA alkali salt. Aqueous medium 0.05 M NaCl or NaBr, pH 10, 25 C. LE-9, linear fatty alcohol...

Phospholipids are digested and absorbed in a similar manner to that of triacylglycerol. Pancreatic lipase has some hydrolytic activity towards phospholipids and removes the fatty acid from the 1-position. The product is a lysophospholipid such as lysolecithin (Figure 4.12). It also acts as a detergent and contributes to the stability of the mixed micelles. 

The structure and thermodynamics of formation of mixed micelles is of great theoretical interest. Micelles are also present and often integrally involved in practical processes. For example, in a small pore volume surfactant flooding process (sometimes called micellar flooding), the solution injected into an oil field generally contains 5-12 weight X surfactant (i) and the surfactant is predominately in micellar form in the reservoir water. In detergency, solubilization can be... 

This brief review has attempted to discuss some of the important phenomena in which surfactant mixtures can be involved. Mechanistic aspects of surfactant interactions and some mathematical models to describe the processes have been outlined. The application of these principles to practical problems has been considered. For example, enhancement of solubilization or surface tension depression using mixtures has been discussed. However, in many cases, the various processes in which surfactants interact generally cannot be considered by themselves, because they occur simultaneously. The surfactant technologist can use this to advantage to accomplish certain objectives. For example, the enhancement of mixed micelle formation can lead to a reduced tendency for surfactant precipitation, reduced adsorption, and a reduced tendency for coacervate formation. The solution to a particular practical problem involving surfactants is rarely obvious because often the surfactants are involved in multiple steps in a process and optimization of a number of simultaneous properties may be involved. An example of this is detergency, where adsorption, solubilization, foaming, emulsion formation, and other phenomena are all important. In enhanced oil recovery. 

Glucagon is a 29-residue hormone whose primary biological role is to stimulate glucose release and production. In dilute aqueous solution the peptide is in a random conformation, but it can be induced to adopt a largely helical conformation under a variety of conditions. Under basic conditions it aggregates to form an a-helical trimer, and the crystal structure of this trimer is known (Sasaki et al., 1975). It also adopts a partially helical conformation when it forms mixed micelles with detergents (Braun et al., 1983). 

Schick, M.J. and Fowkes, F.M. (1957) Foam stabilizing additives for synthetic detergents. Interaction of additives and detergents in mixed micelles. /. Phys. Chem., 61, 1062-68. 

As is obvious from the above discussion, the physical state of the phospholipid substrate is very important in any assay involving phospholipases. Besides the ether-methanol-water system, detergents have been used to prepare mixed micelles with the phospholipids. A widely used detergent is the neutral Triton X-100. A more detailed description of this approach can be gained from material presented in a monograph edited by Dennis (1991). 

The phospholipid and detergent form mixed micelles, dominated by the detergent with its single chain of hydrocarbon the micelles are therefore small. Dialysis lowers the concentration of the water-soluble detergent, so that the micelles become dominated by the phospholipid, which, having... 

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