Biosynthetic incorporation and chemical modification of alkene functionality in genetically engineered polymers

Repetitive polypeptides of sequence [(AlaGly)(3)ProGluGly](16), 3a, have been prepared in Escherichia coli as overexpressed recombinant proteins. Replacement of more than 90% of the naturally occurring proline (Pro) residues with 3,4-dehydroproline (Dhp) in sequence 3a was achieved by in vivo expression of the target protein in medium containing Dhp and lacking Pro. The resulting material (3b) was treated with H2O2 or Br-2 to yield polymers containing 3,4-dihydroxyproline (Dhy, 3c) and 3,4-dibromoproline (Dbr, 3d), respectively, in place of the Dhp residue. These results represent the first demonstration of the incorporation and modification of alkene functionality in recombinant proteins.