Protein stabilisation by polymersome entrapment

We report the use of synthetic vesicles formed by amphiphilic block copolymers in water (or polymersomes) to encapsulate myoglobin varying the vesicle size, and protein concentration. We show that confinement within polymersomes leads to a significant improvement in protein stability against thermal denaturation up to 95oC at neutral pH, with little or no evidence of unfolding or reduced enzymatic activity. The latter parameter actually exhibits a two-fold increase after thermal cycling when the confined protein concentration is higher than 5% v/v. Our results suggest that nanoscopic confinement is a promising new avenue for the enhanced long-term storage of proteins. Moreover, our work has potentially important implications for the origin of life, since such compartmentalisation may well have been critical for ensuring the preservation of early functional proteins under relatively harsh conditions, thus playing a key role in the subsequent emergence of primitive life forms.