OPARINS REACTIONS REVISITED - ENZYMATIC-SYNTHESIS OF POLY(ADENYLIC ACID) IN MICELLES AND SELF-REPRODUCING VESICLES

The enzymatic polymerization of ADP to poly(A), catalyzed by polynucleotide phosphorylase (PNPase) from Micrococcus luteus, has been studied in two supramolecular systems: (a) in reverse micelles formed by sodium bis-(2-ethylhexyl) sulfosuccinate in isooctane and (b) in oleic acid/oleate vesicles at pH 9. In the case of reverse micelles, the reaction 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 proceeded and poly(A) remained entrapped inside the vesicles. The reaction has also in this case been studied under conditions of vesicle autopoietic self-reproduction, namely under conditions in which the vesicles are able to increase their concentrations due to an autocatalytic process which takes place within their boundaries. For this, PNPase was first entrapped inside the vesicles, followed by external addition of ADP and oleic anhydride. ADP permeated across the vesicle bilayer into the interior where PNPase catalyzed the formation of poly(A). In parallel to this endovesicular enzymatic poly(A) synthesis, oleic anhydride was hydrolyzed to oleic acid within the boundaries of the vesicles, which lead to an increase in size and number of vesicles. In this way, 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.