Factors controlling the size of proteinoid microspheres

Proteinoid microspheres were prepared from aqueous solutions containing various metal halides under different pH values and ionic strengths. The effects of pH and ionic strength on the diameter of the microspheres and also the solubility of the proteinoid in hot solution (100 degrees C) were investigated by means of different physiochemical measurements. It is found that, under high ionic strength, the diameter of the microsphere is mainly affected by the salt concentration, while the pH of the system is the main factor when the ionic strength is low. Moreover, the change in the solubility with ionic strength and pH is found to show a striking resemblance to that in the diameter with both factors. On the basis of these results, the external and internal factors controlling the size of proteinoid microspheres are clarified, and a plausible mechanism of the proteinoid microsphere formation under prebiotic conditions is also discussed.