Thermal proteinoids as excitability-inducing materials.

The deposition of thermal copolyamino acids on planar lipid membranes causes oscillations and action potentials upon electrical stimulation. Results are reported for compositionally simple thermal copoly(asp,glu) and for a more heterotonic polyamino acid. The data conform to the interference that electrical activity of cellular membranes is due to the polypeptide components, not to the lipid components. Because of the ease and controllability of producing polypeptides by thermal copolymerization of amino acids, new possibilities in investigation of structure-excitability relationships are provided.

Membrane, action, and oscillatory potentials in simulated protocells.

Electrical membrane potentials, oscillations, and action potentials are observed in proteinoid microspheres impaled with (3 M KC1) microelectrodes. Although effects are of greater magnitude when the vesicles contain glycerol and natural or synthetic lecithin, the results in the purely synthetic thermal protein structures are substantial, attaining 20 mV amplitude in some cases. The results add the property of electrical potential to the other known properties of proteinoid microspheres, in their role as models for protocells.