Exploiting the sequence of naturally occurring elastin: construction, production and characterization of a recombinant thermoplastic protein-based polymer

Abstract

Genetic engineering was used to produce an elastin-like polymer (ELP) with precise amino acid composition, sequence and length, resulting in the absolute control of MW and stereochemistry. A synthetic monomer DNA sequence encoding for (VPAVG)20, was used to build a library of concatemer genes with precise control on sequence and size. The higher molecular weight polymer with 220 repeats of VPAVG was biologically produced in Escherichia coli and purified by hot and cold centrifugation cycles, based on the reversible inverse temperature transition property of ELPs. The use of low cost carbon sources like lactose and glycerol for bacteria cells culture media was explored using Central Composite Design approach allowing optimization of fermentation conditions. Due to its self-assembling behaviour near 33 oC stable spherical microparticles with a size ~ 1μm were obtained, redissolving when a strong undercooling is achieved. The polymer produced showed hysteresis behaviour with thermal absorbing/releasing components depending on the salt concentration of the polymer solution.