engleski

Biophysical studies of fatty acid vesicles as protocell models

Since their discovery in 1973, fatty acid vesicles have been considered as model for protocells, the hypothetical precursor structures of the first cells [1]. Under defined conditions of pH and concentration, fatty acids and their salts - as short as eight carbons in lengths (n-octanoic acid) - assemble into vesicular structures [2]. Recent studies on dilute aqueous mixtures of the potentially prebiotically relevant decanoic acid and its sodium salt showed a complex aggregation behaviour, dominated by the formation of micelles and vesicles, both aggregates being always in equilibrium with non-associated decanoate molecules [3]. The formation of complexes between fatty acids and their soaps in water was shown to occur in the case of the oleic acid/oleate system, and the stabilization of oleic acid/oleate bilayers by intermolecular hydrogen bonding was discussed [4]. An electron spin resonance (ESR) study of the pH-induced transformation of micelles into vesicles showed that oleic acid/oleate aggregates within intermediate pH region is a dynamic system, in which vesicles always coexist with a small amount of non-vesicular aggregates [5]. The aim of our study is to get a deeper understanding of the structural and dynamic properties of fatty acid vesicles by comparing the decanoic acid/decanoate system with the oleic acid/oleate system using four different types of spin labeled compounds. 1. J. M. Gebicki, M. Hicks, Nature 243 (1973) 232-234. 2. C.L. Apel, D.W. Deamer, M. N. Mautner, Biochim. Biophys. Acta, 1559 (2002) 1-9. 3. T. Namani, P. Walde, Langmuir 21 (2005) 6210-6219. 4. T.H. Haines, Proc. Natl. Acad. Sci. USA 80 (1983) 160-164. 5. H Fukuda, A. Goto, H. Yosioka, R. Goto, K. Morigaki, P. Walde, Langmuir 17 (2001) 4223-4231.

fatty acid vesicles; micelles; decanoates

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