P. Walde et al., OPARINS REACTIONS REVISITED - ENZYMATIC-SYNTHESIS OF POLY(ADENYLIC ACID) IN MICELLES AND SELF-REPRODUCING VESICLES, Journal of the American Chemical Society, 116(17), 1994, pp. 7541-7547
The enzymatic polymerization of ADP to poly(A), catalyzed by polynucle
otide phosphorylase (PNPase) from Micrococcus luteus, has been studied
in two supramolecular systems: (a) in reverse micelles formed by sodi
um bis-(2-ethylhexyl) sulfosuccinate in isooctane and (b) in oleic aci
d/oleate vesicles at pH 9. In the case of reverse micelles, the reacti
on proceeded with high yields and with a precipitation of poly(A) out
of the micelles. In the case of vesicles, the poly(A) synthesis also p
roceeded and poly(A) remained entrapped inside the vesicles. The react
ion has also in this case been studied under conditions of vesicle aut
opoietic self-reproduction, namely under conditions in which the vesic
les are able to increase their concentrations due to an autocatalytic
process which takes place within their boundaries. For this, PNPase wa
s first entrapped inside the vesicles, followed by external addition o
f ADP and oleic anhydride. ADP permeated across the vesicle bilayer in
to the interior where PNPase catalyzed the formation of poly(A). In pa
rallel to this endovesicular enzymatic poly(A) synthesis, oleic anhydr
ide was hydrolyzed to oleic acid within the boundaries of the vesicles
, which lead to an increase in size and number of vesicles. In this wa
y, we realized a system in which self-reproduction was accompanied by
a simultaneous growth of RNA inside the vesicles. This can be seen as
a primitive model of a minimal cell.