(579e) Biopolyester Synthesis On Peptide Nanofibers and Liposomes

We present two biomimetic approaches, which control enzyme arrangement at the nanoscale, for production of biopolyester. PHA synthases are enzymes which synthesize polyhydroxyalkanoates (PHAs), a class of biodegradable, biocompatible polymers with use in applications such as degradable medical implants and drug delivery, which are naturally produced by many species of bacteria and archaea. Recombinant expression of the enzyme and addition of a monomer of PHA allow us to synthesize PHAs in vitro, enabling simpler purification of the polymer, but raising the issue of enzyme stability outside of its natural habitat. To address this issue, we have combined PHA synthases with two in vitro support systems: self-assembling peptide nanofibers and giant lipid vesicles. In the first approach, PHA synthases were engineered to associate specifically to peptide nanofibers via a tag peptide, and PHA was then synthesized to coat the surface of the nanofibers. This hierarchical assembly is one of the few examples of the functionalization of peptide nanofibers with an enzyme, and allows rapid attachment of the enzyme under mild conditions, avoiding the harsh treatments of previous methods. The second approach of synthesizing PHAs within a lipid vesicle provides the enzyme with a close match to its natural environment, providing a stabilising structure and raising the potential for establishing an efficient production system which can recycle costly substrates used in PHA synthesis.