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 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.