AUTOCATALYTIC SELF-REPLICATING MICELLES AS MODELS FOR PREBIOTIC STRUCTURES

MICELLES that can catalyse their replication have been described recently 1-3. In the previous experiments, micelles (or bilayer vesicles 4) were always present in the initial reaction mixture-that is, the system was presented with the bounded structures required for autocatalysis. Here we describe a system in which autocatalytic micelles are formed from amphiphiles that are themselves generated from a hydrolysis reaction in the absence of compartmental structures. Alkaline hydrolysis of ethyl caprylate (itself insoluble in water) yields sodium caprylate, initially at a very slow rate; but as soon as sufficient caprylate is formed for aggregation into micelles to take place, there is an exponential increase in reaction rate owing to micellar catalysis. These self-assembling surfactant structures may consequently provide a model system for studies Of prebiotic chemistry. The possible relevance of this process to prebiotic chemistry is emphasized by our observation that the micelles can be converted into more-robust vesicles by a pH change induced by dissolved CO2.