Russell
Posts: 1082
Joined: April 2005
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This guy seems to have thought in an organized way about an aspect of abiogenesis that's been lurking in the back of my mind in an inchoate way for some time. | Quote | Origins of Life and Evolution of Biospheres (2006) 36: 109–150
SURFACTANT ASSEMBLIES AND THEIR VARIOUS POSSIBLE ROLES
FOR THE ORIGIN(S) OF LIFE
PETER WALDE
Abstract.
A large number of surfactants (surface active molecules) are chemically simple compounds
that can be obtained by simple chemical reactions, in some cases even under presumably prebiotic
conditions. Surfactant assemblies are self-organized polymolecular aggregates of surfactants, in the
simplest case micelles, vesicles, hexagonal and cubic phases. It may be that these different types of
surfactant assemblies have played various, so-far underestimated important roles in the processes that
led to the formation of the first living systems.
Although nucleic acids are key players in the formation of cells as we knowthem today (RNAworld
hypothesis), it is still unclear howRNAcould have been formed under prebiotic conditions. Surfactants
with their self-organizing properties may have assisted, controlled and compartimentalized some of the
chemical reactions that eventually led to the formation of molecules like RNA. Therefore, surfactants
were possibly very important in prebiotic times in the sense that they may have been involved in
different physical and chemical processes that finally led to a transformation of non-living matter to
the first cellular form(s) of life. This hypothesis is based on four main experimental observations: (i)
Surfactant aggregation can lead to cell-like compartimentation (vesicles). (ii) Surfactant assemblies
can provide local reaction conditions that are very different from the bulk medium, which may lead to a
dramatic change in the rate of chemical reactions and to a change in reaction product distributions. (iii)
The surface properties of surfactant assemblies that may be liquid- or solid-like, charged or neutral,
and the elasticity and packing density of surfactant assemblies depend on the chemical structure of
the surfactants, on the presence of other molecules, and on the overall environmental conditions (e. g.
temperature). This wide range of surface characteristics of surfactant assemblies may allow a control
of surface-bound chemical reactions not only by the charge or hydrophobicity of the surface but also
by its “softness”. (iv) Chiral polymolecular assemblies (helices) may form from chiral surfactants.
There are many examples that illustrate the different roles and potential roles of surfactant assemblies
in different research areas outside of the field of the origin(s) of life, most importantly in
investigations of contemporary living systems, in nanotechnology applications, and in the development
of drug delivery systems. Concepts and ideas behind many of these applications may have
relevance also in connection to the different unsolved problems in understanding the origin(s) of
life. |
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Must... not... scratch... mosquito bite.
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