Fatty acids micelles

The clay mineral montmorillonite, which is often used in different prebiotic syntheses, is probably now the most important mineral for experiments on prebiotic chemistry. It has shown its abilities in the area of simulation experiments on the formation of primitive cellular compartments montmorillonite accelerates the spontaneous conversion of fatty acid micelles to vesicles. Clay particles are often incorporated into the vesicle, just as is RNA, which is adsorbed at such clay particles. If the vesicles have been formed, they can continue to grow if fatty acids are fed to them via micelles. If the vesicles are pressed through 100 nm pore filters, they divide without dilution of their contents. 

The plasma level of fatty acids in a fed subject is between 0.3 and 0.5 mmol/L. As discussed above, the maximal safe level is about 2 mmol/L. This is not usually exceeded in any physiological condition since, above this concentration, that of the free (not complexed with albumin) fatty acids in the blood increases markedly. This can then lead to the formation of fatty acid micelles which can damage cell membranes the damage can cause aggregation of platelets and interfere with electrical conduction in heart muscle (Chapter 22). The cells particularly at risk are the endothelial cells of arteries and arterioles, since they are directly exposed to the micelles, possibly for long periods of time. Two important roles of endothelial cells are control of the diameter of arterioles of the vascular system and control of blood clotting (Chapter 22). Damage to endothelial cells could be sufficiently severe to interfere with these functions i.e. the arterioles could constrict, and the risk of thrombosis increases. Both of these could contribute to the development of a heart attack (Chapter 22) (Box 7.4). 

Figure 1.2 Structure of a mixed bile-acid/fatty-acid micelle, whereby the hydrophilic (OH groups of BA) are radially arranged on the outside of the micelle and the hydrophobic moieties are arranged on the interior. As well as a classic micelle, a cylindrical mixed micelle structure is also shown.

MA Schwarz, K Raith, G Dongowski, R Neubert. Effect on the partition equilibrium of various drugs by the formation of mixed bile salt/phosphatidylcho-line/fatty acid micelles. A characterization by micellar affinity capillary electrophoresis. Part IV. J Chromatogr A 809 219-229, 1998. 

Another example of ACE analyses of solute-bilayer interactions was described by Roberts et al. (50), who observed retardation of riboflavin by liposomes. Analyses technically similar to liposomal ACE have been performed with mixed bile salt/phosphatidylcholine/fatty acid micelles (95). The partitioning of basic and acidic drugs depended on the acid-base properties of the drug and on the shape and charge of the mixed micelles. 

Micellar catalysis is a broad field (Fendler and Fendler, 1975 Rathman, 1996 Rispens and Engberts, 2001), and caution is needed when using this term. In fact, whereas the broad term catalysis is justihed when referring to an increase of the velocity of reachon, this does not always mean that the velocity constant is increased (namely that there is a decrease of the specific activation energy). Rather, the velocity effect can be due to a concentration effect operated by the surface of the micelles. This is also the case for the autocatalytic self-reproduction of micelles discussed in the previous chapter, where the lipophilic precursor of the surfactant is concentrated on the hydrophobic surface of the fatty acid micelles (Bachmann et al., 1992), a feature that has given rise to some controversy (Mavelli and Luisi, 1996 Buhse etal, 1991 1998 Mavelli, 2004). 

Patterson LK (1981) Studies of radiation induced peroxidation in fatty acid micelles. In Rodgers MAJ, Powers EL (eds) Oxygen and oxy-radicals in chemistry and biology. Academic Press, New York, pp 89-96... 

Figure 8.5 A cross section of a fatty acid micelle.

In addition to bilayers in cell mennbranes and liposomes, phosphatidylcholine also forms micelles. Compare a typical fatty acid micelle (see Section 18.7) and a phosphatidylcholine micelle, both at pH 7. What is the most significant difference in their surface properties ... 

Fatty acids Fatty acid micelles <-> Emulsifier micelles Emulsifier... 

Abietic acid and dehydroabietic acids have been used as surfaetants, either as soaps (sodium salts) or as polyoxyethylene derivatives. The soaps of abietic acids are complex mixtures of fatty acids and rosin acids, and are present in wood extracts from the paper pulp process. The existence of liquid crystals containing these soaps and the effect this has on the tall oil recovery was recognized early [56]. The phase behavior of these mixtures was later investigated by Palonen et al. [57]. It was found that whereas the abietic acid soap only forms a lamellar phase, in the mixture with fatty acid micelles are easily formed that are more soluble in salt solutions than the individual soaps. In order to increase the knowledge regarding the... 

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