Tj. Deming et al., STRUCTURAL MODIFICATION OF A PERIODIC POLYPEPTIDE THROUGH BIOSYNTHETIC REPLACEMENT OF PROLINE WITH AZETIDINE-2-CARBOXYLIC ACID, Macromolecules, 29(5), 1996, pp. 1442-1444
Repetitive polypeptides comprising 16 repeats of the sequence -(AlaGly
)(3)ProGluGly- (1a) have been prepared from Escherichia coli as overex
pressed recombinant proteins. Partial in vivo replacement of the proli
ne (Pro) residues in sequence 1a with L-azetidine-2-carboxylic acid (A
te) was achieved by expression of the target protein in medium contain
ing Ate and lacking Pro. NMR and amino acid analysis for residual prol
ine in the polymer indicated 25-40% replacement of Pro by Ate. While p
olymers of la form conformationally disordered solids, incorporation o
f Aze allows this material to adopt a beta-sheet structure in the soli
d state.